The Kingston Bridge
Part 2: Early Years, Strengthening and Refurbishment
Early Years (1970s and 80s)
A significant reduction of traffic on the existing city centre bridges was recorded in the months after the Kingston Bridge opened. As expected, the number of vehicles using the bridge increased steadily from around 10,000 vehicles per day in 1970 to almost 80,000 by 1980 as a result of the bridge being linked to additional sections of the motorway system. Connection to the Charing Cross section of the Inner Ring Road was made in February 1972, creating a bypass of the city centre for the first time. The Renfrew Motorway, completed in September 1976, extended the M8 to Hillington. Further increases were recorded when the motorway in the east of the city was completed in April 1980.
The bridge quickly became a popular way of crossing the River Clyde. By 1980 around 80,000 vehicles per day were crossing it. This was in line with initial expectations. This photo shows the busy eastbound carriageway in the mid-1970s.
Congestion began to appear on the completed north and west flanks of the Inner Ring Road in the summer of 1980. This was largely because the highway plans of 1965 envisaged that the south and east flanks, which included a second motorway bridge near Glasgow Green, would have carried the bulk of the east-west traffic around the city centre. The cancellation of these sections left the M8 as the only major route across the city, a situation that persists to this day.
The connections to the south flank were built as part of the Kingston Bridge scheme, though they remain unused and can still be seen at West Street.
There have been a lot of changes along the banks of the River Clyde since the completion of the bridge. In this photo from the mid-1970s, the quays have a much more industrial feel. Popular walkways are now present on each side and a leisure complex was opened at Spring Quay in the late 1990s.
Strengthening and Refurbishment
In the late 1980s, a number of structural issues became apparent. At the south end of the bridge the main expansion joint was found to be fully open while at the north end it was closed shut, regular surveys observed the mid-span level of the bridge had dipped and that the quay wall at Anderston was cracking and the timber piles bulging. Damage to the concrete at the base of the main north support pier revealed the culprit—the north pier was itself rotating northwards causing the quay wall to fail.
In a series of further problems, pre-cast facing panels around the bridge copes were dislodged and fell on to the roads and footways below and the aluminium barrier and parapet system was breached in several high-profile accidents.
Strathclyde Regional Council, who took ownership of the bridge after local government reorganisation in May 1975, commissioned an investigation. A draft of the report was leaked to press before it was seen by council officials and the following months brought a media storm with sensational headlines about the bridge regularly appearing in the Daily Record, Glasgow Herald and Evening Times.
Top: The cope and parapet system of the central reservation was replaced following the completion of the main strengthening works. © David Miller (2003).
Above: Sign gantries on the bridge were refurbished to bring them up to modern standards from the mid-1990s.
In one of the most complex projects ever seen on the Scottish motorway system, the Kingston Bridge was temporarily jacked up before each of its main supports were replaced. In this photo the original north support pier can be seen following its careful removal in 1999.
The technical assessments found that elements of the bridge were not behaving as intended and extensive remedial work was required. The council, as roads authority, set up a project team focused entirely on the bridge and its problems, bringing together the brightest minds from the council, academia, consulting engineers and contractors to ensure the issues were fully understood and properly addressed.
Structural monitoring was considered key to understanding the bridge’s behaviour. By 1991, thirty six digital movement sensors, sixteen reflecting prisms, one hundred and twenty eight thermometers and a wind monitor were installed. The sensors provided frequent, detailed data every fifteen seconds. A programme of strengthening and refurbishment followed, starting with jet grouting to stabilise the north quay wall in 1991. A summary of the extensive package of works can be seen below.
The bridge is made up of six hollow concrete box girders positioned in 2x3 arrangement. Additional post tensioning was installed in the late 1990s as part of works to strengthen the structure.
The project team, led by Glasgow City Council on behalf of the Scottish Government after 1996, was disbanded in 2006 following completion of all major contracts. The team was awarded a Saltire Society Civil Engineering Award for its work on main strengthening contract. More recent works have been overseen by Transport Scotland’s Operating Companies which have included Scotland TranServ and Amey.
To date the Scottish Government has invested more than £60 million in the bridge to ensure it can continue admirably performing its key role, keeping cross-city traffic off city centre streets, for decades to come.
Key Facts: Kingston Bridge & Approaches (Strengthening & Refurbishment)
Strathclyde Regional Council orders investigations into bridge problems following indication of structural issues.
Installation of bridge monitoring system. Stabilisation of quay walls. Jet grouting of north quay wall & north pier. Rock armour installed.
Lane 2 closed on each carriageway and kentledge installed. Temporary tie-downs installed. Cope and parapet replacement works commence.
Installation of permanent barrier on eastbound carriageway between lanes 2 and 3. Kentledge removed. Over £8.5 million spent by this stage.
Main bridge strengthening works commence. New piers constructed & movement bearings installed. Additional post-tensioning. Main contractor Balfour Beatty. Works cost £32 million in total.
Concrete half joint bearing replacement scheme (£2.1 million).
Stobcross Off Ramp reconstruction (£4 million). Central reserve cope and parapet replacement (£2.5 million).
Stobcross On Ramp strengthening (£11 million).
Bothwell Street Off Ramp refurbishment (£4.9 million)
South Approaches cope and parapet replacement (£3.25 million)
Newton Street On Ramp cope and parapet replacement (£1.5 million)
North Approaches cope and parapet replacement (£4.5 million*)
* Estimate (June 2020)
To remedy the structural issues the bridge’s bearings and main supports were replaced. This was high profile work, as the bridge could not easily be closed without causing traffic chaos in the city. The contractors proposed a clever method that meant the bridge would only need to be closed over a handful of weekends. Glasgow City Council, working on behalf of the Scottish Government, responded to the huge public interest with a short film to provide an update on progress and to detail what the work involved.
A copy of the film was recently donated to the Glasgow Motorway Archive and we present it here with the kind permission of Transport Scotland.
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