The main activities that have been carried out throughout June have been the continuation of earthworks and drainage works which has been occurring in the fields on both sides of the A46.
The main activities that have been carried out throughout June have been the continuation of earthworks and drainage works which has been occurring in the fields on both sides of the A46. The embankment construction of the Northbound On Slip has been taking shape and various earthworks compaction trials have been conducted to assess the suitability of material on site to be used within the embankments.
The work to construct the new flood compensation area in the old Beekeepers site has been completed and the topsoil stripping work has been taking place in the remainder of the Beekeepers area to allow for the future construction of the new road. Topsoil stripping has also been taking place in the old wet woodlands area in preparation for the major structural operations to construct the new Westley Bridge.
Cadent Gas also commenced work diverting a major gas main on Stoneleigh Road and Dalehouse Lane and in order for this to occur, the speed limit on Stoneleigh Road has been temporarily reduced to a 30mph speed limit, and three way temporary traffic signals have been set up around Dalehouse Lane roundabout to control the flow of traffic. Due to the nature of the Cadent Gas diversion, it is necessary to leave large excavations in the road open and so the traffic signals are presently on twenty-four hours a day, seven days a week. As always, traffic management is constantly monitored to minimise the impact on traffic to and from the nearby Stoneleigh Park Vaccination Centre.
There is still traffic management on the Southbound Off Slip and Northbound On Slip which has closed a single lane on both Slips. This is to allow safe working room for the installation of drainage and earthworks when near the existing carriageway and slip roads and this arrangement will continue to be in place for a few months.
Progress to Date
Cut/Fill Earthworks Activity – New Northbound On Slip and Southbound Off Slip
The main activity taking place on site in June has been the continued earthworks operation to build up the new Northbound and Southbound On Slip roads to the required height. A significant amount of material is being imported to site from a nearby quarry to build up the road. This is necessary as there is an insufficient amount of material on site that could be reused to increase the height. Approximately 1500 cubic metres of material is being imported to site on a daily basis. The ongoing extent of operations can be seen in Figures 1 and 2.
Figure 1 – Earthworks Fill Operations (Looking south at the new Southbound Off Slip (to the left of the A46) and the new Northbound On Slip (to the right of the A46).
Figure 2 – Earthworks Fill Operations (Looking north at the new Roundabout and Dual Carriageway Area).
The material is brought to site and temporarily stockpiled before being moved by large articulated trucks into position. A bulldozer then spreads the material in layers and a steamroller compacts the layers to ensure there is no loose material. Each layer is then tested to ensure the material is suitably compacted before the next layer can be placed. If it fails the compaction test, the layer is stripped, reworked and then re-compacted before being tested again.
As this is a substantial operation with a large area to complete, this operation is expected to go on for a number of months.
Flood Compensation Area
In order to build the new Westley Bridge over Finham Brook, it is necessary to convert an area of land in the old Beekeepers Area to a flood compensation area. This is achieved by lowering the existing ground level to make sure that should Finham Brook flood, it will be this area where the flood water is stored rather than near the new bridge.
This work commenced at the end of May and was completed about three weeks later. As the area was contaminated with Himalayan Balsam (which is considered an invasive species similar to Japanese Knotweed), it was necessary to have a robust procedure in place to ensure the plant was contained. This involved extensive wheel washing facilities for all machinery as well as specialist clothing for site personnel to access the area through a decontamination zone. Figures 3A and 3B show the area before and after the works.
Figure 3A - Flood Compensation Area Before Works
Figure 3B - Flood Compensation Area Before Works
Cadent Gas Works on Dalehouse Lane
As the new road alignment for Dalehouse Lane will impact on an existing gas main, it is necessary to divert it ahead of the main roadworks commencing. This diversion work has commenced and three -way traffic signals put in to allow us to expose the existing pipe in Dalehouse Lane and commence the diversion. This diversion is to ensure gas services are not affected or damaged by the works and prevents any service disruptions during the road construction. The three-way lights are expected to be in place 24 hours a day for the next few weeks.
Ongoing Drainage Works
Extensive filter drainage adjacent to the new slip road alignments have been constructed on both sides of the A46 and this work is complete. These will form bottom of embankment drainage systems and allow the surface water to flow towards proposed attenuation ponds in the area.
As part of this, adjacent to the Northbound On Slip, a length of trench soakaway has been installed. This will allow surface water to be stored and permeate through the subsoil, reducing the outflow into Finham Brook and limiting potential damage to the watercourse and its environment.
Work will now proceed to install the drainage alongside the new road alignment on Stoneleigh Rd West – outside the current site compound.
Further Information
In the coming months, earthworks operations will continue to bring the ground up to the required level. Installation of drainage will also be ongoing.
The tie-ins for the two new slip roads will be constructed. On the Southbound Off Slip, this will require the removal of a large direction sign and a temporary sign will be put up in its place.
It is expected that the traffic configuration of the existing Northbound On Slip and Southbound Off Slip roads will remain in place for the next few months. This is necessary for the protection of the public and road users as well as that of the site operatives.
Further into the future, the construction of the new Westley Bridge will commence by installing temporary works alongside Finham Brook to allow for the driving of piles to form the bridge’s foundations.