The August update on progress towards the A46 Stoneleigh Junction Improvement Scheme.
Overview
Throughout July, operations on site have primarily been the continuation of construction to the new Westley and A46 Bridges along with work to the new Dalehouse Lane Roundabout, Northbound Off Slip, as well as Stoneleigh Road East and West.
Currently, there is still a 50-mph speed limit in place on the A46 mainline to allow safe working for the new A46 bridge construction. This is an aspect of traffic management which will remain in place for the foreseeable future. There is still a 30mph speed limit on Stoneleigh Road, which runs for the entire site extent and will also be in place for the foreseeable future.
Progress to date
Northbound Off Slip Realignment Works
Towards the end of June, the new alignment of the slip road had the final road surfacing laid and is now open to traffic. This replaces the previous arrangement and enables work to switch onto the original carriageway to conduct further works, such as removing the old slip road in order to install drainage, ducting, street lighting and traffic signals. Temporary road markings have been painted which includes give way markings at the top of the slip road. These markings will be in place until the entire slip road is completed and the permanent markings can be applied.
Figure 1 – Northbound Off Slip Progress.
Westley Bridge
A key part of the construction process for the bridge commenced in July which is the installation of the steel reinforcement for the bridge diaphragm. The diaphragm is an important feature as it joins the bridge deck to the abutment and ensures the entire bridge acts as a single structure. Additionally, the permanent formwork panels are currently being installed and will form the bottom face of the bridge deck. These provide a platform onto which the concrete of the bridge deck will be poured. Both operations will continue for the duration of August.
Figure 2 – Steel reinforcement and permanent formwork panels.
New Dalehouse Lane Roundabout
Construction of the new Dalehouse Lane roundabout is now underway following completion of the earthworks for the dual carriageway section. Initially, the area was built up using a mixture of imported sand and site won material to achieve the correct level.
The design of the new roundabout includes a plan to bury contaminated Himalayan Balsam soil in a mound in the roundabout’s central island. This is then covered to ensure the contamination does not spread. This was achieved by excavating the centre of the roundabout to the correct depth and then building benches to stabilise the excavation. This hollow was then then filled with the Himalayan Balsam contaminated material (which had previously been temporarily stored in a special contained section of the site to prevent spread). Over time the area has been built up in layers to a specified height above the existing ground level. Once completed a geotextile fabric was reinstated as well as a layer of topsoil to seal the installation.
This construction can be seen in Figure 3.
Figure 3 – First stage of constructing the Dalehouse Lane Roundabout.
New drainage to the roundabout central island has commenced in this period. Figure 4 illustrates the drainage works and an important aspect involved installing new catchpits and connecting pipes. It is planned that work will continue to progress in this area for the duration of August to complete this specific section of drainage.
Figure 4 – Dalehouse Lane Roundabout drainage system.
New Dalehouse Lane Link
During July, work continued in constructing the new Dalehouse Lane alignment, with progress occurring through installation of the Type 1 road subbase on top of the capping. The next step is compacting the Type 1 subbase using a roller. In addition, some more of the recycled plastic kerbs used elsewhere on the scheme have implemented on both sides of the carriageway, with only concrete edgings being utilised for a small section of footpath which will run alongside the carriageway.
This work can be seen in Figure 5.
Figure 5 – Dalehouse Lane road alignment.
New A46 Bridge
In this period, a concrete pour to the East abutment took place. Steel reinforcement had previously been installed in preparation for. In the west abutment, all formwork has now been removed, with the concrete structure clearly visible from the A46 mainline. The same process will be carried out for the east abutment during some proposed night working which will involve a lane closure on the southbound carriageway and is due to take place in early August. Following this operation, a waterproofing paint will be applied to protect the surface of the concrete.
Figure 6 – West abutment after concrete pour.
Figure 7 – Complete east abutment.
Further Information:
Throughout August, work will continue installing drainage in the vicinity of the new Dalehouse Lane roundabout. Topsoiling parts of it will be carried out at the same time. Following this, work will be to begin constructing the road alignment to the new roundabout by excavating for the road and installing the first aspects of the road foundations. This will be undertaken at the same time as the work being undertaken in the new Dalehouse Lane link, with the completion of kerbing and surfacing occurring within the sections currently be worked on. Further into the future, once the existing Stoneleigh Road has been decommissioned and traffic transferred onto the new network over Westley Bridge, the connection between the new Dalehouse Lane Link and new Dalehouse Lane Roundabout will be completed.
Plans are in place for the installation of the Westley Bridge permanent formwork panels and work will also continue on installing the diaphragm steel reinforcement. For the new A46 Bridge, once the shuttering and waterproofing has been applied to the west abutment, both sides will be at the same stage of construction and attention will turn to building up behind the abutments with earthworks.