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One of our clients is extremely successful in winning large civil contracts where complex and interesting bridges are required – none more so than Chelmer Viaduct in Essex.
This £28M brand new bridge structure spans marshland and ancient pastures as well as the Chelmer river – a total bridge span of around 400mt and 1.25 mile of road replacement. This engineering feat has utilised multiple steel composite beams weighing a staggering 52 tonnes each, all being maneuvered into place by crane.
Rapid ESL were approached to offer bird prevention for the main bridge bearings on each of the river banks to allow access for maintenance and inspection purposes, but no access to pigeons.
This project had a number of design issues we needed to address, including expansion and contraction capabilities (the bridge expands over 6 inches in hot weather) and access to inspection areas at regular intervals – weld mesh gateways needed to be fabricated and installed so the inspection time is reduced. Furthermore, the solution had to be virtually maintenance free and last at least 20 years without issues.
With all this in mind, we designed a weld mesh solution utilising special fixings to allow the mesh to be fixed in one plane only, but still have rigidity to remain an effective bird prevention system. The gateways were also designed to be fixed in one plane as well – the movement of the bridge was compensated for by a unique inter-linking design created and tested for this site.
One other issue was that we were one of the last people on the finished bridge so timeframes and access was really limited, especially as ground workers were laying final curbing and top finishing all around us, ready to open up the walkway underneath.
Working under pressure is never a problem, so machines were delivered and the teams assembled for the works to begin. We split into two teams, one to work on the edge protection and the other to concentrate on fabricating the gateways.
Our teams are multi-skilled so dealing with this type of engineering works is pretty straight forward and soon the teams got cracking and the solution started to be rolled out. We do insist that the client inspects as we go to make sure all specifications are being adhered to and that they are happy with the solution – the main designer visited to confirm all was to specification and was very happy with the work.
One other thing we did not take into consideration was the heat wave sweeping across the UK – some of the highest temperatures ever recorded and we were working under a bridge in very little shade – the heat was immense. Consequently, keeping fluid levels high and sun screen on was a constant job but starting earlier and finishing earlier seemed to do the trick, missing the hottest parts of the day.
Due to the location of the site, staying away can be part of the enjoyment of the job, and luckily the hotel we were booked in had a small swimming pool, this was amazing after a long day on site. Over the week we got to know the hotel staff pretty well and that always helps when you stay away – they made us bacon sarnies for the morning as we left before breakfast.
As with all jobs, you get a few issues along the way, a machine almost always goes a wrong, tools sometimes break but in these difficult conditions with heat and lots of dust, we came out pretty well with few issues that could not be resolved quickly, thankfully nothing delayed the installation.
When we completed one side of the structure, the next challenge was to get the MEWP’s picked up and transported across the bridge to the other side – normally we would drive them but the span was too far and this road is very busy and fully operational, so a flatbed was required to do this. Our MEWP providers work closely with us and the driver quickly had things in hand and we were soon on the other side of the bridge to repeat the installation exactly as the first side.
Once the design is confirmed and known, the second side normally goes really smoothly and this was no exception. The ground workers were pushing had to get us finished so they could apply the final topsoil and plants, so we pushed hard and finished on time.
The client was delighted as this allowed them to get the project finished ahead of schedule and their comments were very positive – we do like working with this client as they are just all really nice people and help all the time – nothing is too much trouble for them and the project team is organised and responsive.
They also like working with us as we share similar values and all work to get the job done, safely and on time.