A21 / A2100 Johns Cross Junction Improvement
Highways Agency
Value: £1.8 million
Duration: 8 months
Completion: June 2003
Project Brief
The scheme was awarded to Tarmac following an assessment by the Highways Agency of our Quality Statement that proved a
thorough knowledge of the contract and presented a full and detailed working methodology.
Tarmac was required to re-model a complex and unorthodox series of give-way junctions into a roundabout. In order to
facilitate the new horizontal alignment of this roundabout a length of the A21 Trunk Road required realignment.
Programming of the Contract
The Tender documents stated a maximum contract duration of 40 weeks. Tarmac's initial proposals gave a programmed 25-week duration which was successfully reprogrammed to accommodate various Client amendments and severe wet weather conditions, yet still complete within 8 months.
The Works
The main scope of works included
· Extensive bulk earthworks.
· Highway re-alignment and reconstruction
· 3.2 km of surface water and land drainage
· Co-ordination with Statutory Undertakers for major diversion works
· Kerbing, footway and other paved areas. (4.8 km of kerbing)
· Removal and renewal of an existing silage clamp
· Road lighting and signage
· Anti-skid and road markings
In order to achieve the proposed vertical alignment of the new roundabout and its approaches, over 15,000m3 of material was excavated by our supply chain partner, Ovenden Civil Engineering. A requirement of the tender was construction of a contractor-designed retaining wall. However following award of the contract an existing BT fibre optic cable was found in the vicinity of this wall, so Tarmac worked with the designer to develop a practical solution to overcome the obstruction. Our pro-active approach led to a £10,000 saving to the contract and reduced the contract programme by one week.
In order to minimise disruption to the local community and road users, re-modelling of this busy junction involved the complex implementation of 13 phases of traffic management. This required extensive liaison with East Sussex County Highways and Rother District Council. In addition, liaison was undertaken with Railtrack to develop proposals for managing the interaction of queuing traffic with a nearby level crossing.
The scheme required the diversion of a BT Fibre Optic Cable, which entailed demolition and construction of new inspection chambers and the laying of several hundred metres of ducting for the diverted cable. In addition an 11kv HV cable had to be diverted to enable reconstruction of the A2100 leg of the new roundabout. Open communication was
maintained at all times with the Client, Seeboard (now EDF Energy) and British Telecom to ensure that the works were completed to the required specification and within programme. The scheme also involved extensive modifications and upgrading of the existing drainage system to accommodate the new carriageway alignment, and construction of new
drainage for the realigned A21. This necessitated construction of a network of drainage ditches with concrete inverts, stepped weirs and the provision of flow attenuation prior to final outfall.
It was also necessary to reconstruct a number of business accesses, create a dedicated school drop-off point and replace numerous footpaths.
Environmental and Sustainability Considerations:
Tarmac is committed to conducting our operations sensitively with a high regard for the environment.
With this in mind 90% of the spoil/clay taken off site was hauled a short distance to the local British Gypsum Works and used in the remediation of a redundant quarry. All planings generated from the removal of existing pavements were used as Type 1 sub-base for footpaths, and all existing pavement quality concrete was crushed and reused as 6F1 capping material.
Environmental fencing was constructed to effect a noise reduction for local residents.
Prior to site clearance operations a number of environmental and archaeological mitigation measures were instigated, which included:
· Erection of chestnut pail fencing for protection of a wild flower verge, in accordance with the requirements of the High Weald AONB Unit
· A bat survey prior to coppicing of a wood
· Arisings from hedge and tree clearance were left at ground level for 72 hours to allow the migration of other native fauna
· A watching brief was maintained by an Archaeologist throughout the topsoil strip
Considerate Constructors Scheme - Bronze Award
Local residents, businesses and a school in the immediate vicinity of the works were encouraged to monitor and take an active interest in the scheme.
Our management team organised a series of presentations to residents and school children to give them details of the works and to warn of the potential dangers of construction sites. The showpiece involved a 3D 'drive-thru' model of the site, giving the audience an early idea of the final appearance of the junction.The scheme involved the construction of
a new access, car park and footpaths for the school.
Throughout the contract Tarmac's Liaison Officer was constantly interfacing with the school to ensure that works were planned with the children's safety and welfare being a primary concern. Our Liaison Officer also attended each monthly meeting of the local Parish Council.
"Tarmac were able to safely deliver this contract well within the specified timescale and despite some unseasonal October weather. Tarmac have
taken a pro-active approach to maintain excellent relationships with the local school and adjacent property owners throughout the Works."
Paul Nash
Project Manager, Atkins
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