Aggregate Industries Contracting and the South West Asphalt business are supplying the prestigious A30 Temple to Higher Carblake Improvement scheme south of Bodmin, Cornwall. The scheme involves dualling the final 5km section of single carriageway of the A30 between the M5 at Exeter and the Carland Cross junction with the A39 north of Truro. This will play a vital role in improving connectivity and reducing congestion, as well as enhancing the future prosperity of Cornwall by encouraging economic growth, aiding regeneration and supporting tourism. Cornwall Council is part-funding and delivering the project in conjunction with Highways England, with funding split 70:30. The new dual carriageway is being constructed alongside the existing road.
The sub-contract packages (pavement) awarded to Aggregate Industries were valued at £6.27m with works due to be delivered over a one-year period. The scheme requires an estimated total of 62,515 tonnes of asphalt and 27,000 tonnes of Cement Bound Granular Mixture (CBGM) to meet the volumes and performance demanded by the contract. To date, (March 2017) with support from our asphalt operational teams at Moorcroft and Melbur plants, we have laid 32,850 tonnes of asphalt (including side roads) 8,151 tonnes of CBGM at 180mm thickness and 11, 818 tonnes of CBGM at 150mm thickness. We also supplied Highways England-standard high-strength concrete for the structures’ abutments and piers.
Flexible composite paving
Across the scheme as a whole, a value-engineering exercise circumvented the need for full-depth construction. To save on natural resources and provide substantial cost savings for the overall scheme, we provided Cement Bound Granular Material (CBGM) Category 16/20 for the sub-base and lower base course on the main carriageway. We also proposed the use of 57 PSV hard-stone binder which has provided a hard wearing, skid resistant surface and enabled traffic to run at up to 40 mph ahead of the final surface course being laid, enabling Kier to traffic early.
To support the build and produce the CBGM, we installed a temporary mobile batching plant within the Kier A30 compound. By batching the material on site, we have minimised CO2e through reduced vehicular movements to site and haulage time costs in order to meet the programme requirements. Water for use in the CBGM mixes is drawn from an underground on-site bore hole rather than from hydrants.
To promote collaborative working, our Contract Manager, Area Manager, Site Engineer and Supervisor attend monthly LEAN workshops with representatives from the Kier, Highways England, Cornwall County Council and other contractors. This enables the delivery team to identify what assists or hinders the contract, maximise outputs and assess the impact on the local economy.
First key milestone
We received recognition from Kier for achieving the first key milestone on 22nd July 2016 - opening three lanes (two eastbound and one westbound) in time for the school holidays when traffic was expected to increase significantly.
Environmental management and sustainability
Environmental management is a priority for the contract as the 5km link runs through many protected sites. The scheme has a full-time environmental manager who works in collaboration with Cornwall Council and representatives from the Environment Agency, Natural England and the Area of Outstanding Natural Beauty (AONB). A large multi-species culvert is being built which will offer a safe haven for wildlife to cross under the newly-built A30 from one side of the moorland to the other.
We have installed an on-site bitumen Mobile Storage Tank (MST) at the Kier compound. The tank is continually powered, allowing us to draw from it at any time. This enables us rely on our own internal plant resource rather than external sub-contractors and has resulted in a £65,000 material cost saving. The batching plant site is situated close to an airfield so a power source was required for an aviation light on top of the concrete silo. A 20 kVA diesel generator was installed running 24/7 but due to the low power requirements on this site, we explored alternative options to the standard diesel generators that would normally be used to run a mobile batching site.
Speedy Hire connected a Firefly 3.5k kVA Cygnus® hybrid power generator to the 20 kVA diesel generator which provided silent power 24/7 for the aviation light 93% of the time. The diesel generator was only switched on when the internal energy storage of Cygnus needed recharging. On average each week, Cygnus® 4:
Saved 966 litres of diesel
Reduced CO2 emissions by 2.58 tonnes
Delivered 690 hours of silent hybrid power (93%)
As part of our graduate and apprenticeship programmes, Aggregate Industries offers one-year industrial placements to students from universities nationwide. Placements offer real opportunities in a variety of fields and support individual learning to accommodate the individual’s strengths and interests. This approach, coupled with our on-going commitment to life-long learning and development, has made a significant contribution to our Contracting division attaining Investors in People Gold status; placing us in the top 3% of accredited organisations across the UK that have demonstrated business improvement through the investment and management of people.