Key information: the latest at A52 Clifton Bridge
Highways England have been carrying out detailed structural investigations to identify the type of repairs needed and are doing everything they can to get more lanes open over the top of the bridge. The repair process involves strengthening the steel work inside the bridge.
Before substantial repairs get under way, structural investigations, calculations and detailed design work need to be completed to ensure they provide the correct engineering solution. Good progress has been made on this in recent weeks while adhering to social distancing guidelines.
The repair programme
Highways England are working with industry leading engineers to get this work completed as quickly and safely as they can. There are three parts to this work, which all take place while traffic continues to access the bridge: investigations; calculations, analysis and design, and then repair work.
1) Investigations:
Concrete and steel are investigated. Some of the work involves removing samples, which are sent away to be tested.
- Some investigations are completed on site, involving specialist staff.
- Both require confined space-trained staff and mine recovery teams.
- The structural boxes inside the bridge are small – too small for someone to stand up. They are also dark, damp and visibility is difficult.
- The boxes are elevated and as such difficult to access. Some access hatches can be reached by scaffold, some by elevated mobile platforms, some by ladder.
2) Analysis of investigations:
As investigations progress, calculations and analysis take place to determine the best repair solution and programme. This work has been taking place over recent weeks, with teams working remotely sharing information online.
- The investigation results undergo analysis, which can vary from being quite simple to incredibly sophisticated.
- More sophisticated analysis involves computer models which themselves can take months to build. They can be 2-D or 3-D.
To do this analysis Highways England need to know:
- The measurements and properties of each and every part of the structure, including its foundations, in fine detail, including how it reacts to traffic and natural elements.
- A completely independent team repeats the whole exercise, with no contact with the assessing team. They then compare and agree the results. This is a legal requirement that ensures safety remains paramount.
3) The repair work:
- The investigations and analysis allow Highways England to design the repair programme.
- All the work will take place underneath and inside the structure so road users on top of the bridge will not see this taking place.
- Highways England will add more steel and concrete to replace that which has been damaged by water over the years or removed during investigations. They will then remove some of the steel and concrete during the repair work.
- Conditions are cramped and individuals are working in areas similar to that of being inside a mine.
- The phasing of the work is critical and will be in two stages.
- Stage 1: We will fix one side of the structure to the left of the lane currently being used by traffic first, to get more lanes back open.
- Stage 2: We will then fix the right-hand side of the bridge to enable us to reopen the fourth (outside) lane westbound.
Keeping Nottingham moving
Highways England are talking to the local authorities, businesses and the emergency services to see what they can do to help keep the city moving while we only have one lane open to traffic.
They have already put measures in place to keep disruption to a minimum. This includes setting up strategic signage on the M1 southbound encouraging people to use the diversion route via the A453 and they have also added in additional mobile signage at the request of the local authority. When and where appropriate to do so, this signage will reference public transport alternatives.
Highways England have offered ongoing support for police presence to keep key junctions in Nottingham city centre clear, as well as introducing yellow box lining on some junctions and support for Nottingham’s traffic control room. They continue to encourage people to consider using alternative routes while we have limited capacity on the bridge.
To deal with any incidents in the roadworks on the bridge itself, Highways England have also put additional CCTV in place which is linked directly to their control room so that they can assist a vehicle breakdown if and when it happens. In addition to this, they have also placed traffic officer resources on the bridge along with specialist recovery teams so that we can move any vehicles out of the way in the event of a breakdown.
Highways England are also working with the local authorities to explore opportunities to increase park and ride facilities. These discussions remain in the early stages and are continuing.