The Wichelstowe Highway Infrastructure Scheme forms an integral part of the long term Swindon Borough Council expansion programme.
This initial phase was designed to facilitate the development and thus creation of a totally new District
Centre at Wichelstowe.
Our works upon this Phase of the project involved the construction of the main community street, together
with associated utility, drainage, kerbing, decorative paving and surfacing works, provision and installation of architectural street lighting, landscaping, horticultural
works, together with the upgrading of the Peglars Way and Foxham Way signalised junction in order to afford
traffic calming and control adjacent to the new secondary school and entertainment facilities.
In addition, whilst works were being undertaken upon the project we were awarded the refurbishment and upgrading works to the historic Swindon and Wiltshire canal traversing the development site. These works were undertaken in order to create an integral focal point to the development.
As part of our award of the contract for the Wichelstowe Highway Infrastructure Scheme we undertook, upon behalf of our Employer, Swindon
Borough Council the Managing Contractor role in respect of all development works being undertaken
adjacent to our works by others.
This role entailed the coordination of development works being by other Principal Contractors and developers i.e. construction of a new 1500 place
secondary school, construction of a new public house and restaurant development to the banks of the canal
which was constructed concurrent with our canal refurbishment contract.
The Managing Contractor role was created by Swindon Borough Council in order to ensure all works were
undertaken effectively and safely and this mitigated disruption to the surrounding existing highway networks.
In order to satisfactorily fulfil this role our site Project Manager held weekly coordination meetings with
representatives from all adjacent developers and contractors.
The highway works involved the following activities:
Traffic management plans were prepared by our site management team for the works required to the signalised junction and the re-paving of existing footways.
Construction of a temporary haul road
Prior to commencing the highway works we designed and constructed a suitable 6m wide temporary haul road approximately 1Km in length to facilitate access to the secondary school construction site and other development plots.
Earthworks excavations for the highway works were carried out in stages to protect the engineered platforms which we had previously constructed. The wider scheme requires a large amount of fill to construct a noise bund along the M4 corridor
therefore all excavation arisings were placed into a designated stockpile for future re-use.
Other contractors working on the development also used the stockpile and as Managing Contractor we coordinated the management of the stockpile to ensure materials were segregated and stockpiled correctly.
Surface Water and Foul Water drainage
The drainage works comprised the installation of approximately 1,250m of Surface Water drainage up to 450mm diameter and 600m of Foul Water drainage up to 300mm diameter.
We also installed a large attenuation tank and fuel interceptor, constructed several drainage swales and hydrobrake chambers.
The foul water drainage was up to 6m deep and due to the poor underlying ground conditions at Wichelstowe the foul drainage could not safely be installed using
traditional trench boxes, therefore we used trenchless techniques using guided auger boring to install the foul drainage.
Cofferdams were constructed at each of the foul manhole chambers to enable the guided auger boring equipment to be installed to carry out the pipe installation.
Utility installation – Diversions and new services
Service diversion works were required due to the realignment of the stub road leading into the development in order to increase the plot size for the adjacent pub / restaurant development. New services were installed for the secondary school, pub / restaurant and for the future development works.
Early pre-start meetings were held with all the stats companies to discuss and agree their programmes for both the diversionary works and the new service installations.
The service diversion works included diversion of a live Medium Pressure gas main, BT apparatus and a 315mm diameter water main. The diversion works needed to be carefully coordinated by our site management team to ensure that the diversions were completed in accordance with our Programme. Any delay to the diversions would have impacted on the adjacent pub / restaurant development construction Programme.
The new service works included the installation of HV and LV cables, the construction of a new sub-station,installation of a 315mm LP gas main, installation of a new 315mm diameter water main, BT ducts and chambers and installation of spare ducts and chambers.
Again, the new service installation works needed to be carefully coordinated by our site management team to ensure that they were completed in accordance with our Programme, so that the services were installed and made live in time for the pub /
restaurant and secondary school opening dates.
Carriageway and footway construction works
The carriageway and footway construction works were carried out in stages as the drainage works progressed. CBR testing was carried out by our geotechnical
consultant on the road formation and Type 1 Sub-base.
The carriageway surfacing was approximately 4,100m2 and footways approximately 1,700m2.
Kerbing and paving works
Conservation kerbs and edgings were installed to the majority of the new roads which also included a central hard strip to Community Street, 2 roundabouts and associated splitter islands, all of which were paved with granite setts.
Aco wildlife kerbs were also required at each gully location however these would not match with the conservation kerbs, therefore we arranged for a local stonemason to cut slots into standard conservation kerbs to match the new kerb lines.
Approximately 1,800m2 of Marshalls marigold block paving and 850m2 of Weinerberger clay paving were laid to the footways in Community Street and 650m2 of imported Portuguese granite setts were installed to the raised table ramps central hard strip
and roundabouts which were installed on reinforced concrete foundations and laid on Steintec mortar.
Upgrading works to traffic signals
To enable the upgrading of the traffic signals in the Peglars Way / Foxham Way junction we installed new traffic signal ducting, chambers, NAL retention sockets
and carriageway loop boxes. The installation of the new traffic signals was carried out by our specialist traffic signals sub-contractor Dynniq.
Installation of tree pits
Before commencing the paving works to the footways we installed 16No tree pits using Deeproot Urban Solutions Silva Cell system. The installation of the tree
pits was challenging due to the presence of all the new services and road crossings which had to be installed before the tree pits could be constructed.
The tree pits required the installation of a geomembrane and geogrid wrap, the installation of Silva Cell crates along with the installation of surface water drainage connections to each pit. Once the tree pits had been constructed trees were planted by our landscaping contractor, paveable steel grilles and irrigation / aeration systems were installed as the paving works progressed.
Canal lining and landscaping works
The design for the canal lining initially required the installation of a GCL liner however given the time of year that the canal lining was to be carried out,
heading into the Winter months, we proposed an alternative more cost effective lining system using imported engineering clay.
The clay liner provided a better tie-in to the adjacent canal towpath sheet pile wall on one side of the canal and a more suitable embankment on the other side of
the canal to enable us to carry out aquatic planting and landscaping works.
We also installed architectural lighting and bollards along the canal towpath and laid approximately 1,500m2 of resin bond screed with Rhine Gold aggregate.
The works also included the following activities:
• Installation of street lighting
• Installation of traffic signs and bollards
• Installation of bus shelters
• Installation of road markings
• Landscaping and planting works
• Installation of street furniture including tree seats, bike stands and litter bins