Tarmac’s use of warm mix asphalts provided an innovative, sustainable and more cost-effective approach to resurfacing the A350 Westbury, Wiltshire.
Using warm mix asphalt meant that the scheme was completed seven days earlier than originally programmed, providing a saving on the overall cost of £70k, principally from traffic management, whilst allowing for an additional 25% more work to be completed. The shorter programme also reduced disruption for local road users and residents.
The A350 Westbury road condition was poor, resulting from the underlying ground conditions that are prevalent in this part of Wiltshire. The road reconstruction would a require a 24/7 road closure, diverting HGV traffic onto the Highways England network, which was already at capacity and other traffic onto lengthy diversions on other local roads.
The scheme was originally planned to commence on 16th September and completion on 11th October. The scheme was to be undertaken in sections, with planned areas to be laid with two layers of 60mm AC 20 HDM Binder, with a 200kn geogrid in between and 50 surface course of 10mm Ultilayer S. Each reconstruction section was to take 1.5 days sections including ancillary works. The total scheme was costed at £470k.
After Wiltshire and Tarmac Contracting collaboratively reviewed the programme it became evident that warm temperature asphalt would provide significant efficiency savings.
The use of warm temperature asphalt throughout all construction layers enabled a more efficient method of working. The lower binder course was completed quicker providing the optimum temperature for the installation of the geogrid much sooner. This efficiency then enabled the upper binder course layer to be installed in the same shift. This also enabled the team to complete ancillary works on other sections during the shift, providing a 0.5 day saving on each programmed 1.5 day section. The earlier finishes during the contract period allowed access for residents to their houses and the town centre.
Results & Benefits
The scheme was completed seven days earlier than scheduled, providing an overall saving of £70k, principally from traffic management, whilst allowing for an additional 25% more work to be completed.
The early completion reduced the diversion and disruption period for through traffic and the local community. Public appreciation was expressed in a complimentary letter published in the Wilshire Times.
Diane Ware, Principal Technical Officer – Highways: “My approach to warm temperature asphalt is, why wouldn’t you? This asphalt provides sustainability benefits, improves site safety and as the A350 Westbury site demonstrates, provides the opportunity to adopt a more efficient way of working in delivering schemes.”
This sustainable approach to highways management contributed to Wiltshire Council being named the most climate-friendly council in England and Wales, according to research by Friends of the Earth that has assessed local authorities’ energy, transport and recycling plans.
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