A477 Kilgetty Bypass - Stepaside Junction
Client: WWTRA / Carmarthenshire County Council
Value: £2.2 million
Duration: 14 weeks
Completion: August 2004
Project Brief
The contract required Tarmac to reconstruct and resurface 5.6km
of the A477 in South Carmarthenshire using ex-situ recycling
techniques.
The A477 is the main traffic route to Pembroke Dock and comprised a 3km section of single
carriageway with the remainder being either dual or an 112m wide three-lane carriageway.
The works also included the addition of 1km of extra lane on the existing single carriageway
approach to Kingsmoor roundabout, and alterations to both Kilgetty and Stepaside junctions.
Background to the Contract
Tarmac had completed two previous ex-situ recycling schemes on behalf of Carmarthenshire County Council
(the WWTRA for the Welsh Assembly Transport Directorate), the A40 Groveland junction to Pwll Trap Junction
and the A477 Castell Neli to Kilgetty in March 2002 and July 2003 respectively. The success of these schemes
led to Carmarthenshire's selection of ex-situ recycling for the Kilgetty Bypass.
The Works
The existing carriageway was planed down to a depth of
320mm (due to the existing lean mix depth in local areas the
depth was 350mm in some areas), in thirteen sections of
300 m. This was agreed in order to keep traffic management
disruption to a minimum. The excavated planings were
transported to a temporary facility at Carew Airfield where they
were accurately graded and mixed with a designed quantity of foamed bitumen and a small percentage of cement to make
cold mix foamed asphalt (Foamix) to be used as the Base layer.
The reconstruction was undertaken by replacing the surfacing
with 220mm of Foamix Base course (30,000t) followed by
75mm of heavy duty binder course (10,000t) and 25mm of
10mm Masterflex surface course (7,000t).
The scheme also included:
- Excavation, new drainage, replacement kerbing and associated civil works.
- Erection of new safety fencing.
- High friction and slurry seal surfacing.
- Replacement road markings and studs.
- Adjustment of existing ironwork to new levels.
- Installation of electrical cabling and lighting of new and existing signs.
"We are keen to use ex situ recycling again, because there are lots of benefits," said Client Project Manager Roger Williams. "About
70% of the road has gone back in to its reconstruction, which is very good in terms of reduced environmental impact. "In comparison to conventional resurfacing with hot mix asphalt throughout, much less premium aggregate has been quarried,
planings have not been deposited at landfill and far less energy has been used in the mixing of the foamed asphalt. We have also
saved £300,000 by recycling around 30,000t of asphalt."
Roger Williams
Project Manager, Carmarthenshire CC
Recycling and Sustainability Considerations
From as early as 1994, Tarmac has undertaken extensive research and development into cold mix foamed asphalt and has laid more material than any other company. By 2006 Tarmac had laid over 400,000 tonnes on motorways, trunk roads, industrial estates and car parks and the process was re-branded as Tarmac FoamMaster.
Tarmac's commitment to recycling and the production of
FoamMaster has been strengthened by the purchase of a two new
Wirtgen mobile recycling plants at a cost of £1m and the acquisition of National Road Planing Ltd (NRP), the UK's largest planing company who have the capability to produce up to
1 million tonnes of planings annually.
Tarmac has developed a system, which can be established both on or adjacent to a site, that uses mobile mixing plants and that can be fully validated. These plants are able to produce base or binder
materials by enhancing recycled aggregates, including road
planings as was the case on the A477 Kilgetty Bypass. Tarmac is the only company in the country able to provide a complete recycled road surfacing solution from start to finish.
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