Where it all began

January 2006
Transport Scotland, the Scottish Government's transport agency, begin detailed development work for a new Forth crossing.

But why do we need a new bridge?  In spite of constant maintenance and investment throughout its lifetime, the Forth Road Bridge is showing signs of deterioration.  Corrosion in the main cables is mainly the result of adverse weather and climate conditions, exacerbated by the increased volume and weight of traffic since it entered service in the 1960s.  

The Forth Road Bridge is a vital link in Scotland's transport network, helping people get to work and move goods around the country.  However, the bridge can no longer be guaranteed to continue to provide the levels of service needed to support traffic on this vital road link across the Forth.  The Forth Road Bridge is managed and maintained by Amey LG Ltd as part of the Forth Bridges Operating Company contract.  Previously this was done by the Forth Estuary Transport Authority (FETA) who commissioned a number of studies to assess the status of the bridge.  

Options to allow the bridge to continue as the main road crossing included:
  1. Completely replacing the cables
  2. Adding a new main cable above the existing cable
  3. Adding a new main cable to the side of the existing cable

While replacing or adding to the cables is technically possible, studies showed that this work would be highly disruptive to traffic over a number of years.  These projects would have taken between 3 and 7 years to complete, causing major disruption to travellers and significant problems for the Scottish economy.  So a decision was made by the Scottish Government to build a new replacement bridge.

Summer Surveys

July 2008
Summer is the peak time for environmental surveys.  Summer sees the arrival of new vegetation, badgers, red squirrels, amphibians, breeding birds, freshwater fish and invertebrates therefore specific surveys for each of these residents has to take place.  

The importance of protecting the marine and shore environment of the Firth of Forth has always been a central consideration of the scheme.  The Forth is rich in environmental features, many of which have special protected status under legislation.  These include:
  • Ramsar sites - wetlands of international importance
  • SPAs - Special Protection Areas which are important habitats for rare and migratory birds
  • SACs - Special Areas of Conservation with listed species of flora and fauna
  • SSSIs - Sites of Special Scientific Interest due to the presence of wildlife, geological or geomorphologic features
  • Country parks, local nature reserves and significant historic gardens
  • Listed buildings, ancient monuments, archaeological sites and heritage conservation areas
  • Various woodlands and specially protected trees
  • Nature conservation areas and areas of landscape value
  • Wildlife reserves
  • Greenbelt zones
  • Rights of way
Where practical, steps to avoid or reduce any potential impacts are taken as required by the contract between the client, Transport Scotland, and the contractor, FCBC, and set out in detail in the Project's Environmental Statement.  This includes land use, geology, contaminated land and groundwater, the water environment, terrestrial ecology, estuarine ecology, the landscape and how it looks, air quality, noise and vibration, pedestrians, vehicle travellers and disruption due to construction.

 
 
 

 

 

And our surveys say...

December 2008
After a year of surveys and investigations into the proposed area in and around the Forth Replacement Crossing, the Scottish Government outlines the key decisions that have been reached as a result of this work.  The key headlines from the report are:

The function of the Forth Replacement Crossing and use of the Forth Road Bridge
The more positive prognosis for the existing Forth Road Bridge allows it to be used as a dedicated public transport corridor alongside the new bridge.  While the existing bridge is not capable of carrying the main burden of all traffic on its own in the future, this approach allows the iconic Forth Road Bridge to continue to play a critical role as a public transport corridor.  With this in mind, a refined, sleeker replacement bridge is possible to complement the existing bridges and the world-famous vista.  It's decided that the new bridge will carry general road traffic and importantly, all heavy goods vehicles.  The refined strategy for the connecting road network combines the use of state-of-the-art traffic management technology, with significant junction improvements and new high-quality dual carriageways.  Using the existing bridge and refining the strategy means that the project is now estimated to cost between £1.7 and £2.3 billion - a cost saving of around £1.7 billion on the original budget estimate.  The Forth Replacement Crossing strategy meets all of the needs with more flexibility and more improved value for money, making sensible use of existing infrastructure and reducing environmental impact.  A year's worth of work has been worthwhile!

The proposed design of the new bridge
It is proposed that the bridge will be an elegant, unique and instantly recognisable cable-stayed bridge that complements the existing road and rail crossings.  It will be counted among the world's leading bridges once built - as it's existing neighbours are.
The design of the bridge has been developed in consultation with Architecture and Design Scotland who have endorsed the design.  The proposed new bridge will have three slender single column towers.  The deck will carry two general lanes of traffic with hard shoulders in each direction.  The hard shoulders on the new bridge will ensure that breakdowns, incidents and any maintenance works do not cause the severe congestions which the Forth Road Bridge experiences.  Windshielding on the new bridge will protect the crossing from the effects of wind and provide a more reliable corridor for heavy goods vehicles.  The selected design is cost-effective in both construction and maintenance, and can be built in the suggested timescales.

The road connections to and from the bridge
Around 4km of connecting roads will be built and tie the bridge into the main trunk road network.  This will include providing a high-quality dual carriageway to link the A90 and M9 in the south.  North of the Forth, a new dual carriageway will connect the bridge to the A90/M90 incorporating junction enhancements at Admiralty and Ferrytoll and road widening between those junctions.
State-of-the-art Intelligent Transport System technology will be used along the full length of the scheme from the M90 Halbeath Junction over the bridge to the M9.  This will improve traffic flow, reduce congestion and improve road safety.  By maximising the use of the existing road network the road improvements proposed will result in less impact on the environment, properties and communities.  

Funding, procurement and legislation
The Forth Replacement Crossing scheme will be promoted via a Parliamentary Bill which will be introduced to Parliament towards the end of the following year.  The project will be funded by the Scottish Government and discussions will be held with the industry over the next few months to allow them to respond efficiently to a tender competition later in 2009.  

The Scottish Government concludes that the Forth Replacement Crossing will be the largest civil engineering project in Scotland for a generation and remains vital to the economies of Fife, Edinburgh and the whole of Scotland.

So onwards to 2009!

 

 

Connecting Roads

April 2009
The location and layout of key road junctions for the Forth Replacement Crossing are finalised following further design development work and consultation with the public and stakeholders.

More than 2,200 people attended exhibitions in a range of venues in Fife, Edinburgh and West Lothian in January 2009 and Transport Scotland received just over 200 responses to their consultation.  The feedback is being reviewed and, as a priority, comments relating to the key road junctions have been factored into the design process to finalise the location and geometry of the junction for South and North Queensferry.  These have also been discussed with representatives of the towns' community councils and local authorities.

The details of the design developments are as follows:

South Queensferry Junction
On the south side of the Forth, new south and north-bound slip roads to and from the Forth Road Bridge and A90 at South Queensferry have been added to the design for use by buses and public transport, effectively extending the dedicated public transport corridor.

The provision of the new slip roads allows the connection to South Queensferry to be moved west, providing direct access to and from the A904 immediately south of the replacement crossing.  The A90 will remain in cutting below the level of the A904 as indicated in earlier design, with a new roundabout positioned at ground level connecting to the A904.

The new design provides signficantly improved public transport priority and more convenient connections onto the trunk road network, reduces the traffic using the A904 Builyeon Road and, crucially, allows the embankment carrying the road south of South Queensferry to be reduced by up to 6 metres, lessening the visual impact on the town.

North Queensferry Junction
At North Queensferry, the proposal is to realign the B981 to connect directly onto the Ferrytoll Road.  This provides a more reliable, simpler and safer access for local traffic travelling to and from North Queensferry both during and after construction of the crossing.

At the same time a dedicated north-bound slip road from the Ferrytoll roundabout onto the A90 has been added to the design.  Castlandhill Road will be realigned and kept separate from the junction, giving local access to Rosyth from North Queensferry.

Public Feedback Report

June 2009
A report detailing how local views on the Forth Replacement Crossing project have helped shape its development was published in June.

The Public Information Exhibitions - Feedback & Outcomes Report documents the feedback received following the exhibitions held for communities both north and south of the Firth of Forth in January 2009.  

The exhibitions - which were held in 12 locations over 12 days - were attended by more than 2,200 people and more than 200 responses were received by Transport Scotland.  The report explains how these have been, or continue to be, taken into account by the project team.

John Howison, Forth Replacement Crossing project director, said: "It is simply fundamental to the project's success that we regularly meet with, inform and seek feedback from affected communities and wider groups to ensure the final project has the right design, and impact on people and businesses is kept to the minimum possible."

"This report shows how we have put our public engagement programme into practice and taken on board views from the local communities in the design of the scheme, making significant changes to the project in the South and North Queensferry areas for example."

"I would like to repeat my thanks to everyone who attended the exhibitions in January and especially those who took the time to give us their feedback and comments."

Since the exhibitions Transport Scotland has continued to meet with communities and in June and July held discussions with local residents, community councils and other affected parties about the construction phase and landscaping and mitigation.  Feedback from these sessions has helped with the development of landscaping and mitigation plans and details of construction.


 

 

Firth of Forth Traffic

March 2010
Two ship pilots have been able to experience sailing in the Forth Estuary with the Forth Replacement Crossing in place.

Steve Michel and Neil Walker from Forth Ports were taking part in week-long trials using one of the world's most advanced navigation simulation models.

Commissioned by Transport Scotland and organised by its joint venture partner JacobsArup, the FRC Main Crossing Ship Simulation Study is necessary to understand the potential effects that the new bridge would have on ship navigation during construction and once built.  This included looking at scenarios such as engine or rudder failure, in order to plan mitigation measures.

The existing computer model of the Forth Estuary at the Maritime Simulation Centre, South Tyneside College had been specially updated to include the Forth Replacement Crossing under construction and completed.

Billy Minto, Transport Scotland's structures team manager for the FRC, said: "This is a very sophisticated simulation system which gives the impression of controlling a ship in the Forth Estuary.  The pilots actually sit in a mock-up of a real ship control room and their field of vision is filled by a realistic computer-generated model of the estuary, existing rail and road bridges, and the new Forth Crossing."

Similar to an aircraft flight simulator, the system allows a number of ship types to be tested in real time situations.  This includes carriers, tankers, containers and ferries, with tug assistance where required.  Day and night conditions can be simulated with factors such as fog, wind, tides, currents and waves altered to test different scenarios.  

Commenting on the results, Billy Minto said: "The report concluded that there should be no significant constraints on ship navigation caused by the new bridge under operational conditions."

"In addition, the simulations provided very useful information which will influence our future planning on aspects such as the navigation lighting system and the use of tugs to maintain the 200 metre exclusion zones during construction."


 


 

The team behind the Queensferry Crossing

July 2011

Who Does What?

September 2011
Building a structure like the Queensferry Crossing requires a real team effort - there are 3 main roles which are pivotal in the building of bridges: architects who design it, civil engineers who check for structural soundness and safety and last but by no means least, the construction workers who build it.

Find out more below!

Architects 
Architects are responsible for designing the places we live, work, play, learn and so much more.  They are trained in the art and science of design and develop the idea for structures then turn those into images and plans for construction.  Architects create the overall look however they must also make sure that their creation is functional, safe and suits the needs of the people who are going to use it.

Architects are involved in all phases of a project from the initial discussions to the final delivery of the completed structure.  They need to have specific skills - designing, engineering, managing, supervising and communicating with clients and builders.  To be successful, an architect must be able to communicate their vision persuasively.  

It's not just the physical bridge design that architects work on - they must also consider the environmental impact of the bridge, the cost and how their design fits in with the surroundings before the build can commence.  Their design also has to be approved by engineers, which leads us nicely onto the second role:

Civil Engineers
Whilst the architect focuses more on the artistry and design of the construction, the engineer is focusing on the technical and structural side.  The engineer has to make sure that the architects designs are functional and safe so more often that not the roles work closely together.

Engineers and architects present their plans on technical drawings called "blueprints".  A blueprint is the detailed drawing that outlines their design.  Before an engineer can approve an architect's design, they have to analyse the design and select materials that can safely uphold the structure.  Different materials have different advantages such as greater strength or greater flexibility.  Steel is better for bridges because it is strong and can be made into long beams.  There are a lot of decisions that go into every minor detail of designing and building structures.  In order to design safe structures that will last for many decades, engineers must stay current on the properties of materials, know about design flaws and research new engineering technology.

So the bridge has been designed, the engineers have done their sums and the numbers add up, so what's next?  Let's build!

Construction Workers
A construction worker is the one to bring these blueprints to reality.  They use a variety of tools and operate machines and vehicles such as trucks and bulldozers.  Construction workers have to wear safety clothing to protect themselves, such as leather work boots with a metal toe, plastic construction hats and goggles to protect their eyes.  Many construction workers also wear brightly coloured orange safety vests so that drivers and other construction workers are able to see them.

 

 

 

Foundations Arrive

April 2012

What is a caisson?

April 2012
Ralf Wiegand, FCBC Technical Manager - Caissons, explains the function of the steel caissons in the foundations of the new bridge.  

"Down the ages, one of the most important elements in the long-term success of any bridge structure has always been the foundations.  In a cable-stayed bridge, which the Forth Replacement Crossing will be, foundations are the key to the stability of the towers which support the anchors for the cables from which the deck is suspended.  Critical to the success of the foundations are the steel caissons."

"The sheer scale of the caissons being used on the new bridge is remarkable.  The largest is 30 metres in diameter - approximately the size of an eight storey building.  It weighs a massive 1,200 tonnes making it one of the largest steel caissons ever sunk down to the seabed anywhere in the world.  The barge transporting them is the length of a Premier League football pitch."

"But what function does a caisson actually perform?  Derived from the French for "casing", essentially a caisson acts as a "mould" enabling the concrete foundations to be formed.  Once the caisson is in place on the seabed and has been lowered down to rock level, it is made watertight and the sediment lying on top of the rock is removed from inside the caisson.  16,000m3 of underwater concrete is poured to the depth of 14 metres below sea level.  This concrete "plug" forms the base of the foundations.  The next stage sees the addition of temporary caisson sections on top taking the caisson structure above sea level.  Sea water is then pumped out, leaving a dry hole in which the rest of the concrete foundations can be constructed." 

"Once the foundations are complete, the main caisson structure stays in place for the entire lifespan of the bridge, acting as a shield protecting the concrete from the ravages of the sea.  The temporary caisson is removed."

"On first arrival in the Forth, the caissons take up temporary residence in Rosyth docks where final preparations are made (for example, installation of pumping systems and lighting circuits) before they are ready for placing in their ultimate resting place on the seabed."

"The positioning process is helped by the fact that, despite the sheer volume of steel involved, the caissons float.  This seemingly impossible feat is achieved because the caissons are constructed with a double skin, causing the cavity in between the two layers to fill with air.  The caissons are floated out to the Forth pulled by tugs.  Once in position, concrete is poured slowly into the cavity forcing the air out and allowing each caisson to sink."

"One other point of interest is the fact that the latest GPS technology will be employed to ensure pinpoint accuracy in the placing of the caissons.  It is something we will only get one shot at - so it is absolutely critical to get it right first time."

Concrete Evidence of Progress

March 2013
The final stage in the completion of the new bridge's foundations will begin this Spring.  Here, FCBC Senior Materials Engineers, John McEvoy, outlines some of the challenges involved in carrying out one of the largest underwater concrete pours ever seen in Europe:

"The route which the new bridge will take across the Forth is now picked out by the position of the three steel caissons and various sheet piled cofferdams which help form the foundations of the bridge's towers and piers.

The operation to backfill the caissons with underwater concrete has been the subject of detailed planning for many months.  At the end of last year, a specially designed concrete batching plant was constructed on-site in the Rosyth docks.  The plant is fully computerised and automated, making it one of the most modern in the UK.  The concrete will be batched here before being shipped out on barges to the middle of the Forth in a continuous operation which, at its peak, will involve up to 100 people.

In operations of this sort, you only get one chance to get everything right.  That's why we are carrying out extensive advance trials in our on-site laboratory to ensure the right mix and consistency of concrete.  These trials are going well.  When the operation starts for real, the team will be required to deliver a total of 33,000 cubic metres of underwater concrete to the three caissons.  The biggest single pour is planned to be 18,200 cubic metres for the South Tower foundation, the plan being to complete the pour in a non-stop process, 24 hours a day, lasting up to two weeks.

Much of the raw materials which make up the concrete - the sand, aggregates and water, for example - is being sourced locally.  At full tilt, the plant will be producing up to 120 cubic metres of concrete per hour, a very high production rate.  That means a truck-load will be leaving the plant every four minutes and making its way to the dockside where it is pumped onto one of the four specially designed barges, each carrying six static concrete mixers on its deck.  These mixers keep the concrete mix "live" as the barges, which were specially fitted out for FCBC by Briggs Marine in Burntisland, are pulled by tugs out to location.  Each mixer carries 12 cubic metres of concrete, giving each barge a total capacity of 72 cubic metres.

On arrival at the destination, the concrete is pumped from the mixers into the foundation caissons through a "tremie" pipe which moves around the inside of the structure on flotation devices in order to ensure an even spread.  The pipe is withdrawn upwards as the concrete rises.  At this stage, the concrete mix is close to the consistency of runny porridge.  This fluidity ensures it settles correctly and any trapped air is driven up to the surface.  Underwater concrete contains a retarding agent to delay the setting process and a waterproofing agent which ensures the substance does not mix with the seawater inside the caissons.  As the concrete level rises, the seawater inside is displaced back into the Forth.  When complete, the concrete will not be visible to observers since the top surface of the completed concrete pour will be 14 metres below sea level.

To put some scale on things, it is worth pointing out, for example, that the South Caisson alone will account for 250 barge trips!

The concrete pour operation is executed in one continuous cycle.  As one barge is discharging its load, another will be returning to dock to fill up again.  A third will be in transit, fully loaded, while the fourth will be in dock filling up.  Each complete cycle - filling up, sailing to the site, unloading and returning to dock - will take up to four hours.

The main challenges in a non-stop process like this are logistical: ensuring a constant supply of raw materials to the batching plant followed by correct batching to produce the right quality of concrete.  Careful management to the plant and having back-up measures to take account of any breakdowns will guarantee the desired, consistent rate of supply is achieved.

A further consideration is the need for us to liaise closely with all marine traffic out on the Forth.  This includes the requirement to vacate the dockside at the North Quay on those occasions when international cruise ships are calling into port.

The team is ready for the challenge ahead and is pleased to be playing a part in one of the most important aspects in the construction of this new historic bridge."

And the finalists are...

April 2013

The Queensferry Crossing

June 2013

Caring for local marine life

July 2013
Liam Soden, FCBC's Ecological Clerk of Works, explains the measures being taken to protect all forms of the life in the waters of the Forth Estuary.

"Care for the environment is absolutely central to the Forth Replacement Crossing Project.  Everybody involved is committed to the rigorous conditions laid out in the contract we have with the Scottish Government and as set out in the Forth Crossing Act Environmental Statement.  Our goal is to ensure that the new Queensferry Crossing sets new benchmarks for work class environmental care in large scale construction projects.  

So what are the particular challenges involved?  Chief amongst them is the fact that the area of the Forth where we are working features a number of designated environmental protection sites.  Firstly, we have a Ramsar site (named after the Ramsar Convention on Wetlands of International Importance) which is an internationally designated area for the protection of migrating and wading birds.  Also in relation to birdlife, the Firth of Forth and Forth Islands Special Protection Areas (SPA) are designated under European legislation.  Bird species common in the area include redshank, bartailed godwit and curlews as well as a wide variety of tern species such as Common, Arctic and Sandwich.

Next, there are two Site of Special Scientific Interest (SSSI), the Firth of Forth SSSI within the estuary and St Margaret's Marsh on the north shore.  Finally, upstream there is the River Teith Special Area of Conservation (SAC) which flows into the Forth.  This is an important breeding ground for three species of migrating fish: Atlantic salmon, river and sea lamprey.  

Our job is to make sure all construction activities are carried out without harm to these nationally and internationally important environmental protection sites and the protected species found in them.  

There is also a range of protected species found in the estuary which include some of the larger marine mammals commonly found in UK waters.  These fall into two categories: firstly, the pinnipeds (or fin-footed mammals) such as the grey seal and the common seal (also known as the harbour seal).  Then we have the cetaceans (from the Latin word for whale) which include dolphins, porpoises and whales themselves.  White-beaked and common dolphins have been known in the area from time to time.  Porpoises are common, if extremely shy, visting the area to feed on fish and squid.  

In the summer of 2012, a pod of 22 Pilot Whales hit the news headlines when they beached themselves on the Fife coast.  Unfortunately, most died - despite the efforts of local people - but nine were saved and promptly made their way upstream under the Forth Bridges in search of their favourite food, squid.  This highlights another factor to our environmental protection work - the requirement to safeguard the benthic (or seabed) habitat which provides an important ecosystem for the benthic invertebrate species including crustaceans (such as crab and lobster) and polychaetes (such as Annelid worms) and echinoderms (such as sea urchins and sea cucumbers), species which themselves are a vital part of the food chain for the mammals mentioned above.

The construction activities likely to have the biggest potential impact on wildlife are the rock blasting and piling necessary for the construction of the various foundation elements.  The blasting is complete now and the piling is well underway with minimal impact on marine wildlife ensured to date.  

A Marine Mammal Observer (MMO) working offshore in a boat is responsible for actively monitoring the movements of all marine mammals in the area.  If any mammals are identified within a 1km radius of the blasting and piling works within 15 minutes of the start of works, then the works are delayed by 20 minutes or until such time as the creatures concerned have moved off.  In fact, this has happened on several occasions, most commonly with seals being found in the vicinity of Beamer Rock which is the site of the new bridge's Central Tower.  This monitoring is made possible by using state-of-the-art Passive Acoustic Monitoring (PAM) equipment.  A hydrophone, lowered into the water from a boat, employs acoustic echo location signals (similar to a whale's) to locate the position of any wildlife in the water.  

Last year, this equipment, specially designed for FCBC, quickly picked up the presence of the pilot whales mentioned above and closely monitored their movements upstream and, a few days later, downstream.  We are also employing a fish deterrent.  Boat-mounted sonar equipment sends out a signal which deters both shoals and individual fish from coming within 500m of our works.

In addition to liaising closely at all times with Transport Scotland and their advisors, Jacobs Arup, our environmental team also meets regularly with a wide variety of local bodies such as local authorities, Scottish Natural Heritage (SNH), Historic Scotland and Marine Scotland to keep them briefed on our activities and what is happening out on the water.  

Working in estuarine waters brings many challenges not found on land-based construction projects.  FCBC has a team of five environmental specialists with experience of working on large infrastructure projects on land and water.  We are proud to be fulfilling the stringent environmental requirements of the contract whilst, at the same time, helping to ensure the smooth running of the construction works."

 

Cofferdam Placement

November 2013

Lifting the Cofferdam sections from dockside

November 2013

First South Viaduct Push Launch

December 2013

Why Steel?

February 2014
For 150 years, steel has been used in bridge construction.  Steel's versatility gives architects the capability to create their new and exciting designs.  It is one of the most sustainable materials available thanks to its strength and durability which allow it to be recycled over and over again without losing quality.  

Joshua Ishibashi, FCBC Senior Engineer, Cable Stay Bridge Superstructure, explains why steel is the ideal material for the Queensferry Crossing: "Charles Darwin's "Origin of Species", published in 1859, was hot off the press when steel first began to be used in bridge construction.  Steel's potential for major civil engineering projects developed rapidly on both sides of the Atlantic from the middle of the 19th century onwards.  Essentially an alloy of iron ore and carbon, this wonder material marked the end of wrought iron's domination as a construction material."

"Quite which bridge was the first to be built of steel is still disputed today, but certainly the Eads Bridge over the Mississippi River in Illinois, completed in 1874 and almost 2km in length, was one of the first significant bridges to use steel as its primary structural material.  In the UK, the Forth Bridge, which opened in 1890 after seven years of construction, took the use of steel in global bridge construction to a new level.  Today, it remains one of the most impressive feats of civil engineering anywhere in the world and, of course, instantly recognisable to millions of people.  Next door, the Forth Road Bridge is made principally from steel and, at the time of its opening in 1964, featured the longest single bridge span in Europe."

"Today, FCBC has the historic task of building another bridge across the Forth, this time a cable-stayed, as opposed to a suspension, bridge.  Once again, steel is the main construction material being employed.  Several key components of the new bridge are being fabricated in steel: these include the foundation caissons, the bridge deck and approach viaduct structures, the vehicle restraint system, the all-important stay cables and the anchor boxes which will secure the stay cables to the bridge's three towers, thereby connecting the towers to the bridge deck."

"So, what makes steel the ideal material for our task?  There are several features which make it unbeatable:
  • Strength and weight: first foremost, steel is one of the strongest materials at the civil engineer's disposal but it is also relatively light.  So it has a high strength-to-weight ratio which means that bridges can be built with inherent strength without being excessively heavy.  Weight is usually the main enemy facing a bridge builder - unduly heavy bridges are rarely safe bridges.  And lightweight construction techniques also bring cost benefits, not just in terms of construction but also cheaper transportation.
  • Durability and versatility: steel is an incredibly resilient material capable of withstanding everything that extreme weather and climate conditions can throw at it.  Steel bridges are commonly designed to have service lives of well over 100 years during which time degradation will be negligible.  In addition, it is an extremely versatile material able to be shaped in any number of ways to create aesthetically pleasing end products.  On top of this flexibility, steel has a tense strength which allows it to be bent and pulled, perhaps due to strong buffeting from side winds.  These features result in a product whose integrity and strength is easily maintained in complex and lengthy structures, whether vertical or horizontal.  In short, it is ideal!
  • Reliability and availability: the combined effect of these properties is that steel is a thoroughly reliable material.  Over the years, expertise in its use and capabilities has grown internationally to the extent that, today, it is the best understood construction material in the world.  It is also readily available throughout the world, being manufactured in most industrial countries.  
  • Speed of construction: a further advantage of the reduced weight of steel is that components can more easily be pre-fabricated off-site and transported to site ready to be installed.  This is in contrast to other material - such as concrete, for example - which are best produced on-site due to their sheer weight.  Pre-fabrication greatly reduces assembly times on-site.  
  • Recyclable: finally, steel is recyclable.  Indeed, it is the most recycled construction material in use today.  When a steel bridge - or, for that matter, individual elements in it - reach the end of their useful life, the steel can be removed, cut into manageable sizes and returned to the steelworks to be melted down and re-used to manufacture new products."  
"For the technically minded, the grade of steel mostly used in the Queensferry Crossing is "S355J2 + N".  This means it complies with the latest international quality construction standards.  We are sourcing steel fabrications from a variety of countries including the UK, China, Poland and Spain.  We are employing the latest, highly developed dehumidification and external coating techniques to ensure that the steel in the new bridge, especially in the cables, is protected from the damaging and corrosive effects of prolonged exposure to extreme weather conditions.  Such corrosion on the existing Forth Road Bridge has, of course, been a factor in the decision to build a new bridge in the first place."

"To summarise, steel is strong, light, versatile, durable, reliable, quick to install and environmentally responsible.  What's not to like?  There is no other material that can compare with steel, especially in the construction of large infrastructure projects such as the Queensferry Crossing.  Its use is a thoroughly tried and tested technology, ideally suited to deliver a new major European bridge capable of meeting the demands that will be put upon it over the coming decades."

 


 

Queensferry Crossing Flythrough

April 2014

South Approach Viaduct Timelapse

April 2014

Centre Tower Timelapse

May 2014

Delivery from Shanghai

May 2014

Steel Operation

May 2014

Meet the Neighbours

September 2014
With the Forth Road Bridge celebrating it's 50th birthday this month, let's look at the Queensferry Crossing's more established neighbours - two of the most iconic bridges in the world.

The Forth Bridge
It is believed a permanent bridge across the Forth was first considered by the Romans.  At the beginning of the 19th century, a tunnel from South Queensferry to Rosyth was considered but, at a cost of £160,000, it was soon abandoned for economic reasons rather than any doubts about its feasibility. 

In 1818, a bold proposal for a suspension bridge was put forward.  With some justification, this ambitious design was later judged to have been so fragile that "on a dull day it would be hardly visible and, after a heavy gale, no longer to be seen on a clear day either" (William Westhofen, "The Forth Bridge", 1890).  Construction work never got underway.

With the development of steam power during the century, railways became the main transport carrier across the country and it became clear that a rail bridge was what was required.  The pioneering Victorians, always ready for an engineering challenge, were just the people to deliver it.  

A railway crossing of sorts first operated across the Forth using the Granton to Burntisland ferry installed by Thomas Bouch in 1850.  This operated until the Forth Bridge was opened in 1890.  Bouch, one of the most famous civil engineers of his generation, also came up with a design for a suspension railway bridge at Queensferry.  Construction work began - part of a support pier can still be seen at Inchgarvie - but was abandoned in the wake of the collapse of the Tay Bridge in 1879 - of which Bouch was also Chief Engineer.  

Often referred to as the "Queen of Victorian bridges", and a UNESCO World Heritage Site since 2015, the Forth Bridge represents the pinnacle of 19th century civil engineering prowess and is one of the world's most recognisable engineering wonders.  It perfectly reflects the "great age of steam" in which it was designed and built - and is still, of course, a vital element in Scotland's rail network today.

There are many myths and legends which surround the oldest of the Forth Bridges however the most famous is that the bridge is being continually repainted.  In 2011 this myth was finally debunked as restoration works ended marking the first time the entire structure had been repainted in its history.  With an expected lifetime of 20-25 years, there is no need for the painters to be back in place just yet.  And just in case you were curious, the paint name of the iconic colour is now officially known as "Forth Bridge Red".

Forth Road Bridge
When the Forth Road Bridge opened in September 1964, it was one of the most impressive feats of engineering of the age - just as its neighbour, the Forth Bridge, had been 74 years earlier.  

Finally replacing the ferries which had plied the route for 900 years, the bridge represents the technological advances made by the mid 20th century in response to the burgeoning age of the motor car.  On opening, the bridge was the fourth longest suspension bridge in the world, the first long-span suspension bridge in the UK and the longest in Europe.  

In the 1960s, around 4 million vehicles used the bridge to travel over the Forth Estuary every year.  Today, this figure is closer to 24 million, an increase of almost 500% - far higher than the national average traffic growth - with approximately 70,000 vehicles crossing the bridge every day.  Such volume of traffic would have been unimaginable over 50 years ago when the bridge was under construction.


The Forth Road Bridge was designated a Category A listed structure in March 2001.

Laying the Deck

October 2014

South Approach Viaduct Launch II

November 2014

Review of 2014

December 2014

Changing Landscapes

January 2015

Ferrytoll Viaduct beam lifts

March 2015

View from the South

April 2015

Lifting pier N1 cofferdam to position

April 2015

That Lucky Old Sun

June 2015

Completing the South Approach Viaduct

June 2015

Cabling Compilation

September 2015

Deck Fabrication

September 2015

The B800 Bridge Story

September 2015

First Deck Lifts

September 2015

How to build a road deck

September 2015
This autumn marks the start of one of the most technically challenging periods in the construction of the Queensferry Crossing - the operation to lift the bridge's deck segments into place and install the all important stay cables.  Carson T. Carney, FCBC's Cable Stayed Bridge Technical Manager, explains the complex processes necessary to ensure all 110 deck segments are installed successfully.

"Over the past two to three years, looking out across the Forth, local residents and members of the public have been able to see key elements of the new Queensferry Crossing growing in front of their eyes, week-by-week, month-by-month.  The three main towers, for example, reaching ever higher into the sky and now significantly higher than the towers of the neighbouring Forth Road Bridge.  Or the Approach Viaduct South being steadily launched out over the water."

"What hasn't been so obvious is the ongoing work to the deck which will ultimately carry many thousands of vehicles across the bridge every day.  This is about to change as we enter the next phase of building this amazing bridge: installing the individual deck segments and the stay cables which will hold them up.  By filling the gaps between the three towers and connecting to the viaducts, these segments will, for the first time, actually begin to make a bridge out of the structure we are building."

"The first four deck segments on each tower have already been installed.  These are connected directly to the towers supported by temporary "falsework" trestles beneath.  At the North Tower, the initial deck segments have recently been lifted off the falsework and tilted to give them the required geometry to fit the graceful arc which the final, completed road deck will form.  This tilting - we call it "rotation" - was achieved through the recently installed first stay cables taking the weight of the deck for the first time in late August, a significant milestone in the project."

"Starting from early September, all subsequent deck segments will start to be lifted into place with their reinforced concrete decks already in place having been cast and fitted in FCBC's on-shore fabrication yard in Rosyth Docks.  This lifting process will last throughout a good part of 2016."

"Here is a brief description of the processes we will have to complete 110 times between now and the completion of the bridge deck:

Step 1

Each deck segment, weighing 750 tonnes on average, is transported out from the dockside fabrication yard on one of two huge barges positioned by tugs.  On arrival to the tower site, the barge is anchored - to within a tight 200mm tolerance - beneath the blue erection traveller cranes positioned up at deck level, one either side of each tower.  These erection travellers will lift the deck segment up to deck height (approx. 55 metres) in a delicate operation which lasts about two hours in which wind, sea and tide conditions will all play a critical part.  Each deck segment is then rotated by a few degrees in order to match the final geometry of the completed bridge deck and a series of interlocking plates are joined together to hold the structures in place.

Steps 2 & 3

Once the segment has been correctly positioned, it has to be fixed permanently in place.  This is achieved by a huge amount of welding around the steel box structure and internal beams within it.  This is a time-consuming operation but a critical one as a perfect top weld is vital to allow the reinforced concrete "stitch" to be poured on top of the structure.  This stitch, along with the welds, permanently secures the segment to its neighbour.  These operations are constantly monitored by non-destructive test inspections to ensure perfect positioning is achieved after which permanent bolts complete the steel connections.

Step 4

Whilst the reinforced concrete stitch is being poured, the stay cables have to be prepared.  The stay cables are one of the signature features of the Queensferry Crossing.  They consist of a varying number of strands (up to 109 for the largest cables) which are threaded through an external white pipe (essentially a covering or sleeve).  Each strand is made up of seven high tensile, galvanised steel wires, 5.2mm in diameter.  Six of the wires, coated in wax, are wound in a helix pattern round a central king wire which is straight.  The strands are each contained in a high density polyethylene (HDPE) coating.  Think of it this way: 7 wires = 1 strand.  A bundle of strands up to 109 strands = 1 stay cable.  The external white pipe is welded to the correct length and a single strand is threaded through.  The pipe is then lifted into position using the enormous, yellow Tower Crane.

Step 5 & 6

The remaining strands are then threaded through the pipe using a winch and shuttle system which brings the strands through the pipe one at a time.  Each strand is cut to length and wedged into a steel anchor plate at either end.  The final result is one of the strongest steel cables in the world, capable of supporting the Queensferry Crossing road deck for many decades to come.  By the end of Step 6, the stay cables - two per deck segment - have been fully assembled and tested but the weight of the deck segment is still primarily being carried by the blue erection traveller cranes.  The stay cables are now tensioned up to final tension at which point the weight of the deck segment is transferred from the erection traveller crane to the stay cables.

Step 7

The hydraulically powered, 250 tonne erection traveller can now move forward (typically 16.2 metres) on rails to the leading edge of the newly installed deck segment ready to lift the next segment making its way out from the land - and the above cycle is repeated.  

"On completion of all 110 deck segment installations, the stay cables will be finely adjusted to achieve the "global geometry" required by the design of the new bridge.  Taking into consideration the massive weights and loads involved, the dramatic heights at which we will be working and the variable weather and sea conditions which Mother Nature will doubtless throw at us in this exposed, maritime location, the operations to install the road deck represent leading edge civil engineering at its most raw and exciting - and we cannot wait to get on with it!"

Milestones for the CEC

October 2015
The visit of fifty S4-S6 pupils from Greenfaulds High School in North Lanarkshire marked a milestone for the Contact & Education Centre (CEC) - the 10,000th pupil to visit!  

This has been achieved in only two full academic years, a mark of Transport Scotland's commitment to forging a lasting educational legacy.  Since the Schools Programme began in 2013, over 400 school visits have taken place with schools from all over Scotland coming on-site to find out more about the construction of the Queensferry Crossing and undertake Science, Technology, Engineering and Mathematics (STEM) related challenges.  

Cabinet Secretary Keith Brown presented the group with photographs of the construction of the new bridge and special Queensferry Crossing souvenirs.  

Mr Brown said: "We have never lost sight of how inspiring the construction of the Queensferry Crossing would be, especially being situated alongside the other two iconic Forth Bridges.  The popularity of the CEC has been a real vindication of the importance we have placed in community engagement from day one.  The Outreach and Education Programme has attracted over 40,000 people so far and we anticipate interest growing further as the bridge reaches its final stages."


Turning to the network connections, the major demolition of the old B800 bridge over the A90 dual carriageway outside South Queensferry was successfully completed on schedule this month.  On the north side, construction of the new Ferrytoll gyratory continues to proceed well and late October saw one northbound lane of A90 traffic successfully diverted onto the first stretch of the new M90 motorway on the project, support by new structures recently completed for the new gyratory below.


 

B800 Bridge Demolition

October 2015

Drones over the Queensferry Crossing

December 2015

Review of 2015

December 2015

Decks Halfway There

March 2016
By the end of March, the halfway point in the deck section lifting operations is reached.  55 out of a final total of 110 sections have been lifted, each weighing an average of 750 tonnes.  The sections are held in place by high-tensile steel stay-cables formed on-site.  Eventually, the deck sections and signature stay-cables will carry the road surface all of us will be driving across in the years to come.

Keeping a close eye on wind and tide conditions, each section is lifted from barges by one of six "erection traveller" cranes situated at each of the leading edges of the emerging deck.  The lifting operation takes four hours and, once underway, cannot be halted.  The team liaise closely with the Met Office to identify "wind windows of opportunity" where they can be certain of being able to complete the operation.  A lifting schedule is planned around the wind forecasts which can mean lifting a section at any time of the day or night and sometimes two sections on the same day.  Once at road deck height, each section is bolted and welded into place while a reinforced concrete "stitch" is laid to complete the top surface.  Then begins the process of inserting and tensioning the stay-cables which will carry not just the weight of the section but also, after completion, the road surface, passing traffic and wind load which, on occasions, can be considerable out there.

March also saw the completion of the launch of the Approach Viaduct North.  In one of the most technically challenging operations of its type ever performed, the launch involved shifting the massive steel and reinforced concrete structure, with a total launch weight of 6,300 tonnes, some 230m out towards the North Tower.  

What made this operation really special is the fact that the team had to slide the trailing edge of the moving structure down two ramp walls and pivot the structure over the top of one of the two support piers beneath, rather like a gigantic seesaw!  This raised the front edge by 2 metres, resulting in the viaduct structure being at the correct geometry to match the emerging deck coming from the North Tower.

Ferrytoll Demolition

March 2016

North Approach Viaduct Launch

March 2016

Cable the News!

April 2016
The highly visible white cables which form the Queensferry Crossing's emerging "fans" are one of the new bridge's signature features.  Brian Gordon, FCBC Cable-Stayed Bridge Construction Manager, explains how the cables are made and fastened into position.

"The Queensferry Crossing is a cable-stayed bridge.  In fact, when complete it will be the longest three-towered, cable-stayed bridge in the world.  But what does "cable-stayed" mean?  Essentially, a cable-stayed bridge transfers the massive weight of the road deck directly through the cables to the towers which are anchored to the seabed.  On a suspension bridge (such as our neighbour, the Forth Road Bridge) the weight of the road deck is carried by the two main cables which are held aloft by the towers are are anchored on land at either end."

"On the Queensferry Crossing, the finished road deck will weigh an amazing total of approximately 100,000 tonnes, so the job the cables are going to be asked to do is considerable to say the least!"

"Typically, each pair of parallel cables on the Queensferry Crossing supports an individual road deck section below.  In mid span, however, this bridge will uniquely feature some sections which will be supported by four cables, the cables coming from neighbouring towers crossing over in a diamond pattern.  In all, the bridge will have 288 cables, the longest being 420 metres and the shortest 90 metres.  Here's how we make them.  Each cable consists of a number of strands (up to 109 for the largest cables) which are threaded through an external white pipe.  This pipe is essentially a protective covering or sleeve made from high density polyethylene (HDPE).  Each strand is made up of seven high-tensile, galvanised steel wires, 5.2mm in diameter.  Six of the wires, coated in wax, are wound in a helix pattern around a central "king wire" with is straight.  The strands are also sheathed in an HDPE coating.  Think of it this way: 7 wires = 1 strand.  A bundle of strands (up to 109) = 1 cable."

"The external white pipe is welded to the correct length while lying flat on the road deck out at each tower.  A single strand is threaded through the pipe before it is lifted up and fixed into position on the tower using the enormous, yellow tower cranes connected to the side of each tower.  The remaining strands are then threaded through the pipe using a winch and shuttle system which brings the strands through the pipe one at a time. Each strand is cut to length, tensioned and wedged into a steel anchor plate at both ends using small, high-tensile steel wedges.  The result is one of the strongest steel cables in the world, capable of supporting the Queensferry Crossing road deck for decades to come."

"The beauty of the cable-stayed system lies in its ease of long term maintenance.  In years to come, if an individual strand needs to be replaced, it can be simply pulled out and a new one inserted.  This process can take place without significantly affecting the strength of the cable in question, with no ill effects on the operation of the bridge and with no disruption to the flow of traffic.  This is where the cutting edge bridge technology is "at" in the 21st century and the Queensferry Crossing will become one of the finest exponents of the system anywhere in the world."

 

Delayed Opening

June 2016
In June, it was announced that the Queensferry Crossing would open to traffic by May 2017 not, as previously targeted, by the end of 2016.  The project is still on target to have traffic flowing in both carriageways before its contractual completion date of June 2017.

Since September 2015 the downtime due to adverse weather, especially wind, has been 40% compared to the 25% anticipated by the contractor.  Until May, FCBC believed that they could mitigate these effects however the impact of the weather in April and May with 13 and 12 days lost to weather was such that they can no longer deliver the December 2016 target.

In order to mitigate the ongoing weather impacts that have arisen over the past few months FCBC has procured additional physical resource, increased staffing by taking on an additional 100 workers, increased working hours, altered construction methodologies where possible and challenged critical construction sequences to identify where any programme efficiencies could be found.  They have now reached the stage where further additional resources will not bring the delivery date forward due to the complex technical nature of the construction work.  In addition, the remaining construction activities can only be carried out sequentially, further limiting the ability to make further gains.  Specifically the bridge deck and cable installation process which began in September 2015 is particularly sensitive to wind and this increases as the cables used become longer and are installed at a greater height.

The project is, at all times, at the mercy of the weather.

Weathering the Weather

June 2016
With the weather impacting the progress of the Queensferry Crossing, Florian Dieterle, FCBC's Cable-Stayed Bridge Temporary Works Coordinator, looks at the challenges posed by the Scottish weather when lifting the deck sections which form the new Crossing's road deck.

"Since September last year, FCBC has successfully lifted 80 deck sections from sea level to road deck level on the Queensferry Crossing.  Each lift operation is a major civil engineering feat in its own right.  Remember, the structures we are lifting weigh on average around 750 tonnes (or roughly 54 London buses - with passengers!), they measure 40 metres by 16 metres by 5 metres (so they're big!) and we have to lift them up an incredible 60 metres (200ft) into the air!  To top it all, we are carrying out these operations in the middle of a wide, exposed, maritime estuary.  This is tough civil engineering.  It's a huge challenge and, every day, we face a number of significant, mostly weather related variables which govern how well each lift will go and how long it will take."

"Let's start with wind.  We cannot begin lifting such huge structures in wind conditions over 21 knots.  Wind can cause the road deck, on which the blue "erection traveller" crane is situated, to move, albeit fractionally, just as it is designed to do.  This could have a knock on effect on the movement of the deck section once it becomes airborne making precise control difficult.  That's why we liaise very closely with the Met Office to identify suitable windows of opportunity where we can be confident of being able to start and complete a lift operation in safe, low wind conditions."

"Wind also affects when we can lift the main stay cable pipes into position.  If we cannot finish and fully tension the cables supporting the previously installed deck section, then we cannot move the erection traveller forwards and, consequently, cannot start the next deck lift.  Our operations out there are sequential.  One stage has to be fully completed before the next can begin.  If wind delays the completion of one operation, then subsequent operations will also be delayed."

"Days can sometimes be lost waiting for the right wind conditions.  Even in May this year, when the country experienced three or four consecutive weeks of warm, sunny weather, we lost some working days due to continuing variable and blustery wind conditions out on the Forth."

"Then there's fog.  As local residents will testify, the Forth estuary is prone to mist and fog, known locally on the east coast of Scotland as "haar".  Good visibility is vital so that the barge carrying the deck section can sail out from the dock to the tower site and allow us to start the lift operation itself.  For safety's sake, we have to be able to see every part of the operation.  Powerful floodlighting means that, if necessary, we can perform a lift in reduced light conditions just as well as during the day.  That is particularly important in the winter months with their shorter days."

"Sea conditions are also important to a successful and timely deck lift.  We can lift in both falling and rising tides, but waves of over 0.3 metres (1ft) in height can result in movements in the barge which could affect the way the deck section begins its journey upwards.  So we have to pause and wait for the waves to subside."

"So wind, fog and waves are the main "enemy".  Other conditions, such as rain, snow, ice or even a sudden heatwave pose less of a challenge though may bring some staff safety considerations.  We don't necessarily object to bad weather - if it happens at a time which leaves us free to get on with our day jobs unhindered!"

 

 

All About the Approach Viaducts

July 2016
Conventional construction methods, i.e. excavation, blinding concrete, shutter and reinforced concrete, are used for the three land-based pier foundations - two on the southern viaduct and one on the northern viaduct.

A total of 10 piers (eight on the south, two on the north) support the two approach viaducts connecting the bridge to the wider road network.  The piers comprise:
  • V-shape concrete piers with steel cross ties
  • Hollow reinforced concrete cross section legs 
Construction method: climbing formwork (also known as shuttering), 4m in height, to create a mould into which concrete is poured.  The formwork is stripped and re-erected once the concrete gains sufficient strength to be self-supporting.

On the Queensferry Crossing, there are two approach viaducts linking the bridge to the land on either side of the Forth.  The viaducts' principal function is to take north and southbound traffic to and from the new, cable-stayed bridge.  While not strictly part of the bridge structure itself, the viaducts are vital to the successful performance of the whole structure.  No viaducts, no functioning bridge!

The viaducts' superstructure features steel box girders joined together by bolts and welds.  Both viaducts comprise:
  • Steel and concrete composite decks, overall width 39.8m
  • Steel composite box girders
  • Reinforced concrete deck
  • Steel corrosion protection by de-humidification system

The steel superstructures of both north and south approach viaducts were built on land behind the bridge abutments.  They were then launched out over the viaduct support piers, pushed and pulled by means of hydraulic jacks and cables called strand jacks.  Temporary king posts and cables were used to support the front edge of the cantilever to counteract deflection and allow the structure to pass over the piers.

The stats

South Approach Viaduct
  • 2 steel box girders, one for northbound traffic, the other for southbound traffic
  • Built section by section in 33m lengths weighing 72 tonnes and fabricated by Cleveland Bridge Ltd in Darlington
  • Launched out incrementally over 6 piers as new sections attached to trailing end
  • Total length of viaduct: 543m
  • Total weight of viaduct, including concrete deck: c.20,000 tonnes

North Approach Viaduct
  • 76m of twin steel box girders (similar to South Approach Viaduct)
  • 146m of single, full width steel box girder
  • Launched out over the 2 support piers in a single operation.  During launch, entire structure "pivoted" over pier N2 raising leading edge 2m to meet road deck coming from North Tower
  • Total length of viaduct: 222m
  • Total weight of viaduct, including concrete deck: c.6,300 tonnes





Centre Tower from the sky

September 2016

Centre Tower Cantilever Deflection

September 2016

How to close the gaps

October 2016
Senior Design Engineer with the Queensferry Crossing's Design Joint Venture, Martin Romberg, explains the challenges involved in closing the gaps successfully.

"We have now lifted and installed 104 out of a total of 110 deck sections which will eventually form the Queensferry Crossing's motorway road deck which, in less than a year's time, will be carrying tens of thousands of vehicles across the Forth every day."

"At 6.1m by 40m by 5m, the deck sections used to close the gaps between the main deck spans are smaller than the main deck sections but, nevertheless, weigh a massive 300 tonnes.  It is a technically challenging operation to slot these sections into place because the space to be filled between the main deck spans, constructed over the past 14 month, is incredibly narrow.  In fact, as the section completes its journey upwards we only have 100mm clearance on either side, representing exceptionally tight tolerances.  So complete accuracy during the entire lifting operation is absolutely vital.  To help with this, we push the entire South Tower deck span back by 300mm using powerful hydraulic jacks attached to the South Tower itself.  This creates a gap sufficiently wide to allow the closure deck section to slip into place."

"The next step is to join the newly arrived section to the South span in much the same way as all the previous deck sections have been installed - by welding it into place before pouring a reinforced concrete "stitch" across the top of the joint to create the final deck surface on which the blacktop will eventually be laid.  Unlike other deck sections, the closure sections are not bolted into place, but a series of temporary tension bars pull the two decks tightly together allowing the welding operation to take place."

"Once the section is fully attached on one side to the South deck span, we are ready to attach the other side to the neighbouring Centre Tower deck.  Before we can do this, however, it is vital to check that the horizontal and vertical alignments are an exact match.  By altering the tensioning of the stay-cables supporting the already installed deck sections, we can lift the two leading edges to exactly the correct geometry."

"When everything is ready, we slowly release the compression on the jacks at the South Tower so that the over 600m long South Tower deck span can move back the 300mm, thus closing the gap and allowing the other side of the closure section to be welded and concreted into position.  When this is complete, full closure has been achieved."

"A total of four principal closures will be carried out on this amazing construction project.  So far, we have successfully achieved two.  As with most things on this job, the principal challenge is the weather.  Hundreds of measurements and checks are carried out before and during the closure operation to minimise the risk of anything going wrong 60m up, but the one thing we cannot control is the famous wind out in the Forth."

 

 

Centre Tower Movement

October 2016

Record Breakers Part 2

October 2016

Closing the Gaps

October 2016

Centre & North Tower Final Deck Lift

November 2016

Review of 2016

December 2016

Queensferry Crossing Slideshow

January 2017

All roads lead to...the Queensferry Crossing!

January 2017
The construction of the Queensferry Crossing doesn't just end at the Crossing itself, its impact is felt over the surrounding areas and connecting roads.  The introduction of the Queensferry Crossing has resulted in the below changes to the road networks: 

M9 Junction 1a
This contract has improved connections and reliability by widening the M9 at key locations, improving existing slip roads and providing new west-facing connections between the M9 and M9 Spur (now renamed M90).  The original connections between M9 Junction 1a and the M90 have been improved to provide two lanes and a hard shoulder to help traffic flow through this busy junction.  Improved connections with West Lothian have also been provided by including new west-facing slip roads between the M9 and M90, requiring a new bridge across the M9 and extension of the bridges over Overton Road and Newmains Road.  To complement these improvements, the section of the M9 north of Newbridge Junction has been improved with an additional lane being added in both directions from the River Almond bridge to M9 Junction 1a.

Principal Contract (south of the Forth)
From the south tie-in, the new motorway will leave the A90 and the M90 at Scotstoun, to run westwards, parallel with the south side of South Queensferry before turning north to skirt round Echline corner.  We have created a two level interchange, incorporating the A904 and B924 which will allow access to and exit from Queensferry Crossing and the motorway.  The motorway will then pass between Springfield and Clufflats to the east and Linn Mill to the west.  The south abutment of the new bridge lies 150m south of Society Road and the motorway will pass over Society Road via the South Approach Viaduct.

Principal Contract (north of the Forth)
The motorway on the north side will sit between Admiral's House to the west and the Queensferry Hotel to the east, 150m to the west of the existing Forth Road Bridge.  The new road will cut at approximately 8m in depth through St Margaret's Hope rock outcrop and immediately go onto the new Ferrytoll embankment, which will be up to 26m high, to carry it past St Margaret's Marsh and towards Ferrytoll Junction.  At this point, the existing Ferrytoll Junction will be reconstructed 15m to the west and 100m north of its existing position.  The main carriageway will tie in to the existing A90/M90 between Dunfermline Wynd overbridge and Admiralty roundabout.

Throughout the new network, various side roads are realigned and altered to cater for public transport and local traffic.  The new motorway will comprise 4km dual three-lane (new or improved) and 2.5km dual two-lane carriageways in addition to realigned and reconstructed ancillary roads.  The work will also include a state-of-the-art Intelligent Transport System (ITS) which will help regulate the flow of traffic on the approaches to the new bridge, forming part of a 22km ITS corridor that extends from the M9 in Newbridge to the M90 Halbeath Junction.  Overhead signal gantries along this corridor will provide lane control, variable mandatory speed control and traffic information to drivers via variable message signs (VMS).  Being able to use the existing Forth Road Bridge and dedicated bus lanes provided under the overall FRC Project, bus travellers will be able to enjoy uninterrupted passage from Halbeath to Newbridge.
 
 
 
 
 

Bridge Structure Complete!

February 2017
2017 gets off to an exciting start with the preparations for the installation of the very last deck section, SS25.  February sees this "last piece of the jigsaw" successfully lifted into place, completing a pioneering deck installation process which began in September 2015.  On any bridge project, the closure of the final gap represents a major milestone - perhaps the most significant of all.  In civil engineering terms, the creation of the Queensferry Crossing's 2.7km road deck (with a total of 122 sections, weighing an average of 750 tonnes each, lifted up into position 60 metres above the Forth estuary and weighing an incredible combined total of approximately 85,000 tonnes) has been a massive undertaking.  It is 21st century, leading edge civil engineering at its best.

Good progress continues to be made right across the construction works.  On the south approach viaduct, the casting of the final reinforced concrete deck section is all but complete and operations are underway to lay the vital waterproofing membrane and the final "black top" road surface as well as to install the windshielding panels.  Waterproofing has also started along the length of the main bridge deck.  Also at deck level, the installation begins on four massive expansion joints, one at each end of the north and southbound carriageways, which allow for the constant movement in the deck structure created by traffic volume, wind load and ambient temperature.

Beneath road deck level, the complex operation to remove the temporary steel structures at each tower, known as the tower trestles, begins.  Their main function was to support the first deck sections positioned around the towers but they remained in place providing a platform for office units and workshop accommodation which have now been moved up onto the deck.

At the same time, the decommissioning and dismantling of the three yellow tower cranes - the tallest cranes in the UK - has begun, starting at the North Tower.  Once the cranes and falsework have been removed, the removal of the steel caissons at the foot of the North and South Towers and the cofferdam at the foot of the Centre Tower can begin.

Working through a big "to-do" list

February 2017
With the last of the 122 deck segments installed this month, the Queensferry Crossing's structure is essentially complete.  But a huge amount of work remains to be done before the bridge is finished and traffic can start flowing across what is one of the world's greatest bridges.  Alan Platt, FCBC Construction Director, summarises the finishing works to be completed to allow the bridge to open:

External Works: the most visible

Stay cables: 
by February there are still six pairs of stay-cables to be installed.  These are the longest on the whole Project so the experience gained over the past 15 months in threading the individual steel strands which make up each cable through the long external white pipes will be invaluable.  Each of the 288 cables is individually load checked to ensure the correct geometry of the road deck below and to make sure they will perform their function to the optimum for many years to come.

Road surface: from abutment to abutment, the laying of a specialist waterproof membrane on top of the reinforced concrete deck is now in full swing.  This membrane protects the concrete from the potential harmful corroding effects of rainwater sitting on top.  Next, we will place a layer of hot rolled asphalt over the membrane before the final course of low noise "black top" is laid and the road surface is complete.

Expansion joints: being installed at both ends of each carriageway between the bridge's road deck and approach roads, a total of four expansion joints will ensure the road deck can move - as it's designed to do - vertically, longitudinally and laterally according to current traffic load, ambient temperature and wind load.  These are some of the largest expansion joints ever manufactured and installed, accommodating an impressive range of 2.3 metres of movement.

Wind & noise barrier: unlike the Forth Road Bridge, the Queensferry Crossing features a modern wind barrier system designed to reduce the impact of the wind on traffic, therefore keeping the bridge open to traffic in all but the rarest and most extreme of weather conditions.  In total, we will be installing 5.7km of 3.6 metre high, open-louvred windshielding panels along the east and west edges of the entire structure on the Ferrytoll viaduct just north of the new bridge.  At the southern end of the bridge, the wind barrier will be further enhanced to help mitigate the impact of traffic noise on nearby residents.

Vehicle restraint system: more commonly known as "crash barriers", these will also be installed along the road deck on both sides of the carriageways.

Lighting: various types of lighting systems have to be installed on the structure.  The road lighting on the bridge is limited to the ends of the structure at the approaches to the road junctions.  This lighting is provided by modern, low level street lights which illuminate the carriageways whilst reducing light pollution.  There is also architectural lighting built into the wind barrier as well as up and down the towers which will ensure the distinctive shape and structure of the bridge is highlighted at night.  Finally, for safety, there are marine navigation and aircraft warning lighting systems to be installed across the structure.

Inspection gantries and cradles: in order to allow regular inspections and maintenance of the steel undersides of the deck, four mobile gantries will be installed, between them capable of covering the full length of the road deck.  Two further gantries carry out the same function on the approach viaducts.  Tower inspection cradles will also be provided.

Tower cranes: the beginning of the year saw the start of the decommissioning and dismantling of the three enormous yellow cranes (at approximately 235 metres in height, the highest anywhere in the UK) which have stood next to the Queensferry Crossing's towers for the past three years and more.  Work on this will continue for a few more months.

Falsework: the six temporary steel "trestles" (known as falsework) either side of each tower below deck level and the temporary work platforms they support have to be removed.  Indeed, the first came down in late January.  Weighing several hundred tonnes each, these temporary structures will be pivoted at the base of the towers and lowered onto a barge below before being removed for re-cycling.  

Caissons & cofferdams: other temporary steel structures due to be removed in the next few weeks include the temporary caissons around the North and South Towers and the cofferdam at the base of the Centre Tower on Beamer Rock.  Their removal will allow the sea to come in and lap directly against the towers whose concrete is specifically designed to be impervious to the effects of water.

Internal Works: less visible, just as crucial

Abutments: fitting out the north and south abutments will continue over the next couple of months to provide office, workshop and storage space as well as access to the inside of the road deck.  The abutments are also the hub of all services that are provided in and onto the bridge (for example, power, water, drainage, security and CCTV).

MEP works: "MEP" stands for mechanical, electrical and plumbing and covers the installation of a wide range of hardware vital for the successful long-term operation of the Queensferry Crossing.  Principally these include the power supply (and an emergency back-up supply in the event of power cuts) needed to power all the various items of electrical appartus used to operate the bridge.  

Deck shuttles: running the entire length of the bridge, inside the steel deck, will be two monorail shuttle cars, one for each carriageway, which will be used to transport equipment and personnel for bridge inspections and during periods of maintenance.

Dehumidification: currently being set up is a high capacity dehumidification system which will keep the inside of the steel road deck and the towers dry and free of any condensation or damp.  Moisture will always find a way into any structure, but eight high capacity dehumidifiers are being installed which will keep the air inside moving and minimise moisture in the bridge's interior.  

Lifts, stairways and walkways: the inside of each tower will feature a stairway from sea level to tower top and, additionally, a lift from road deck level up to the top of the tower.  Inside the steel deck, no less than 7.5km of walkways will allow access to the entire structure.

Drainage: a system of drainage pipes and outlets is being installed along the length of the bridge to allow rainwater to drain away easily and efficiently from both the road surface and other areas of the bridge.

Cleansing water: passing vehicles (in the case of the Queensferry Crossing likely to be in the region of 25 million vehicles per year) always make a bridge dirty and in less optimum condition.  So, a system of water pipes and taps is also being installed in the bridge to enable the various structural elements and such things as the lighting and wind barrier panels to be kept clean and in good condition.

Control Room: the long-term operation of both the Queensferry Crossing and the Forth Road Bridge will be the responsibility of the bridge operators, currently AMEY, based in their Control Room in South Queensferry, a couple of kilometres from the new bridge.  A comprehensive network of electrical cables and fibre optic cables is being laid to connect the bridge's hi-tech operating systems to the Control Room where all the bridge's systems will be monitored 24 hours a day.

Structural health monitoring: this system measures various parameters relating to the structure of the bridge and indicates how, over time, it is coping with the loads it is being asked to handle under different conditions such as wind, temperature, movement and deflection.  Linked sensors constantly monitor and store a wide range of data which is fed back to the Control Room.

CCTV and fire detection: the bridge will feature the latest CCTV technology to allow the bridge operators in their Control Room to monitor traffic movements and any other activities on the bridge.  A comprehensive fire detection and alarm system is also due to be installed in the coming weeks.  

Security: across the structure, there are over 300 access ways and doors.  Each one is locked and most have active security systems, working in tandem with the CCTV cameras, to alert the Control Room should there be any unauthorised access to a particular area.

The Queensferry Crossing in Numbers

March 2017
The scale of the new Queensferry Crossing is enormous but don't just take our word for it, the numbers speak for themselves:
  • 15...days of pouring concrete 24/7 to achieve the Queensferry Crossing's first world record for the longest continuous underwater pour.  The concrete was poured to the foundations of the South Tower.
  • 23...Kelpies could be built using the same amount of steel required in the build of the North and South viaducts (the start and end of the Crossing).  7,000 tonnes of steel was used just for these sections.
  • 25...percent higher than the Forth Road Bridge.  The Queensferry Crossing will be 207 metres above high tide (683ft) which is 50 metres higher than the Road Bridge.
  • 48...London Buses that you would need to stack on top of each other to reach the same height as the towers of the Queensferry Crossing.
  • 65...options were considered before the cable-stayed bridge design of the Queensferry Crossing was selected as the best to proceed with.
  • 110...deck sections which make up the bridge deck.  Each one of these sections can weigh up to 750 tonnes!
  • 200...Boeing 747 planes are the equivalent weight of the amount of steel required for the bridge deck. 
  • 23,000...miles of cabling used.  Laid out, this would very nearly stretch around the entire planet Earth.
  • 150,000...tonnes of concrete poured over the course of the project.  This is nearly the same amount used for the entire London Olympic Park and Athletes Village.
  • 10,000,000...man hours approximately that were involved in the construction.

Finishing Works

April 2017

Almost there!

June 2017
The focus moves onto the the completion of a wide range of complex "finishing works" which have to be carried out before the bridge can open to traffic.  Here's a brief look at recent progress.

Out in the open, perhaps the most obvious change has been the removal of the three yellow tower cranes.  For the past four years and more, these have stood parallel to the bridge's three towers where they grew to an amazing height of 235m, making them the tallest cranes anywhere in the UK.  Dismantling such vast structures, section by section, was an operation requiring careful planning, thorough risk assessment and suitable weather conditions.  The winter and early spring turned out to be fairly benign in some ways with generally mild weather and none of the extremes of bad weather sometimes experienced.  However, they were also almost continuously windy and those above average windy conditions made the job of bringing the cranes down more difficult, leading to it taking somewhat longer than planned with a consequential knock-on effect on other related activities.

Once the cranes had been removed to below road deck level, work could be carried out on filling the gaps in the deck's cantilevered hard shoulder where they had previously stood.  That work is now complete, as is the removal of the six triangular steel trestles, two either side of each tower, which had formerly supported the weight of the first deck sections to be installed and which provided platform areas for offices, welfare areas, storage and other work facilities during construction of the road deck.  These huge temporary structures, known as "falsework" and weighing several hundred tonnes, made for a dramatic sight as they were lowered in one piece on to barges to be taken away for re-cycling.  

All of the bridge's stay cables have now been fully installed.  Further progress has been made on installing the transparent windshielding panels which will protect vehicles on the bridge from the effects of the famous Firth of Forth winds.  In parallel with the windshielding, a total of 10.8km of vehicle restraint barriers (or "crash barriers") are being installed on either side of each carriageway on the bridge.  Almost complete is the laying of a waterproofing membrane on top of the concrete road deck.  This membrane protects the reinforced concrete deck from the adverse corrosive effects of rain water by promoting the flow of water into drains at the sides of the roadway.  As sections of deck have been waterproofed, we have been able to start the process of laying the final road surface over which traffic will drive.

Inside the deck "tubs" many other operations are unerway which come under the heading of "ME works".  These include things like the connection of electricity supplies and cabling, lighting (both internal and external) and the installation of monitoring systems which will ensure the smooth operation of the bridge for decades to come.

Following the final deck section lift in February and subsequent closure of the remaining gap between the South Tower road deck and the southern approach viaduct, the last significant concrete pour of the entire construction took place in late March when the final sections of road deck were laid on the southern approach viaduct.  Throughout the Project, FCBC's batching plant in Rosyth Docks has produced a staggering total of around half a million tonnes of high quality concrete, a proud record.  











Powering the Bridge

July 2017
One of the current areas of focus is on installing the electricity supply needed to power the various systems which will control the fuctioning of the bridge and monitor its performance for decades to come.  Graeme Sharp, one of FCBC's Mechanical, Electrical & Plumbing (MEP) Engineers, explains the importance of electricity to the new bridge:

"The Queensferry Crossing will provide a vital link in our trunk road network and fulfil an important role in the economy for decades to come.  In order to function properly and safely in all weather conditions night and day, it has many installations which require a reliable electricity supply.

We are currently installing a variety of lighting systems on the bridge structure and its immediate approaches.  These include road lighting which will be placed between the nearest trunk road interchanges an the bridge to improve safety.  This lighting is provided by modern, low level lighting bollards which illuminate the carriageways whilst reducing light pollution.

There is also an architectural lighting system built into the windshield structure as well as floodlights to illuminate the three towers which will ensure the distinctive shape of the bridge is highlighted at night.  Finally, in order to comply with safety regulations, we are installing high intensity LED marine navigation and aircraft warning lighting systems at the top and bottom of each tower.

The latest traffic management technology called ITS (Intelligent Transport Systems), will feature on all the trunk roads approaching the Queensferry Crossing using overhead sign gantries to give drivers live travel information relating to journey times, incidents and diversions as well as mandatory variable speed limits.  ITS will extend on to the bridge itself via cantilevered sign gantries attached to the towers.  These, too, require electricity to operate.

However it is below road level inside the deck "tubs" that the bulk of the systems requiring electricity are to be found.  The bridge's interior needs an effective lighting system from end to end to enable maintenance crews to see what they are doing.  Other installations which rely on electricity include:
  • dehumidification systems to control humidity and inhibit possible corrosion
  • elevators to transport maintenance crews up and down the towers
  • maintenance monorail shuttles
  • 1,500 structural health sensors which monitor and record "real time" information on how the bridge is coping with the various loads it has to handle under different conditions, such as wind and temperature
  • CCTV, access control and fire detection systems

These systems will enable the bridge operators - AMEY - to put in place reliable, evidence-based control and future maintenance programmes using accurate and comprehensive historical data.  Obviously, a dependable source of electricity is absolutely vital, so we are installing emergency back-up generators which will automatically spring into action during any unplanned cuts in supply.

Installing, testing and commissioning all these electrical systems on the bridge and its approaches is a complex operation involving the laying of several hundred kilometres of electricity and fibre-optic cables.  Electricity will lie at the heart of the successful, day-to-day operation of the Queensferry Crossing."

Once in a lifetime

September 2017


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