Company News

DBFO 1 Project 3 M2 Junction 3 to 4

In June 2008 a joint venture between Extrudakerb and their Irish partner Highway Barrier Solutions, was awarded by the principle contractor, HMC Joint Venture, a £2.2m sub contract to design and build a central reserve concrete barrier, retaining wall and associated linear insitu concrete drainage system.

Extrudakerb / HBS partnership have integrated within the HMC Joint Venture team with their designers Arup to ensure that their Client’s Road Service, demands and expectations were fully realised by the Extrudakerb design.

Extrudakerb’s designers Norder, worked closely to develop an industry first: a concrete barrier system and retaining wall to accommodate carriageway level differences of up to 1.2m. The system based upon the Britpave Concrete Step Barrier is primarily slipformed with some conventional hand poured foundation elements.

The concrete structure needed to meet the structural requirements of a carriageway retaining wall and that of the foundation for a Britpave concrete barrier system.

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The brief stipulated that the overall width of the barrier system should not exceed 1.0m, not too difficult for a standard barrier with a footprint of only some 542mm. However carriageway street lighting had to be sited within the central reserve.

As a standard Britpave Wide CSB has a footprint of some 942mm Extrudakerb and their designers spent many, many hours in brain storming meetings to develop compliant but ground breaking structural design as well as minimum clearance width paving moulds, to meet this demanding overall width requirement.

The solution developed saw the construction of insitu mass poured foundations and two parallel CSBs placed in very close horizontal proximity to each other and each aligned with the adjacent carriageway such that their base level differences were up to 1.2m.

Reinforced concrete build outs were designed by Norder upon which 15m high street lights are mounted. A special reduced depth cradle anchorage was developed by Fixing Centre to fit within the limited space available.

Bespoke steel formwork was designed and manufactured by Extrudakerb for each uniquely shaped light column build out.

Where existing carriageway levels were less than 300mm a standard Britpave variable profile barrier was incorporated. To allow for the incorporation of street lighting along the line of the central reserve the wide version including a longitudinal trough where ducting and cabling is installed was constructed.

This variable profile Wide Britpave barrier was constructed using one of Extrudakerb’s variable profile moulds. These moulds are designed and fabricated in house where the blend of experienced slipform contractor and machinery manufacturer has resulted in class leading technology.

In line with Britpave Specification heavy duty stainless steel anchors, again supplied to Extrudakerb by supply chain partner Fixing Centre, were installed and tested by Extrudakerb.

Specific transition details from the twin barrier system to the standard wide variable Britpave barrier were designed and constructed by Extrudakerb again using bespoke steel formwork manufactured in house.

Asymmetric and symmetric transitions were required from the barrier systems to existing strengthened concrete bridge piers and concrete sign gantry bases. The Britpave design was developed by Extrudakerb and Norder to simplify construction and meet specific project demands.

Insitu concrete drainage channels and slot drains were developed as well as the associated outfall chambers and gulleys. In total over 4,500 metres of insitu concrete drainage system was slipformed.

Separate formwork gangs worked in tandem with the slipform paving crew to ensure that these works progressed concurrently with the main line slipform elements. In fact it was the completion of this formwork construction that proved to be the critical path for the works.

Extrudakerb utilised a number of their own HGVs fitted with integral Hiab cranes to transport and handle the heavy steel formwork that had been specifically designed and fabricated for this project.

In total some 8 lorry loads of equipment were shipped from England to Belfast; including over 50 metres of barrier steel forms and 7 slipform paving moulds.

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Paving works were carried out using one of Extrudakerb’s four Gomaco Commander III slipform machines. Like all Extrudakerb’s slipform pavers the machine was set up in a 4-track configuration and the machines ability to mount moulds to both sides again proved vital allowing paving to always progress in the same direction as adjacent traffic flow therefore avoiding the need to turn supply wagons around on a congested and narrow site.

The paving and shuttering crews were supported by a fleet of some 6 medium vans that carried both the manpower and their specialised equipment.

Extrudakerb set up a local site office to better manage construction on site. Crews from England travelled to Belfast working two full weeks on and one long weekend off. Throughout the works all vehicles and equipment remained in Belfast stored in the principle contractorís site compound, Extrudakerb purchased minibuses that were used to transport the crews between England and Belfast.

An original 4 month programme developed by Extrudakerb to best meet the critical path of this complex scheme was completed some 4 weeks ahead of schedule with principle works completed by the end of November 2008.

Concrete to this project was again supplied by Cemex; Extrudakerb and HBS’s supply chain partner in Northern Ireland.

Mix was based upon previous proven design although some tweaks were made to suit variations in currently available local aggregates.

Outputs peaked at over 24m3 per hour with the company’s previous daily productivity records being exceeded.

In total over 8,000m3 of concrete were supplied to the barrier works.

Concrete supplied to the barrier works was independently tested for Extrudakerb by Mattest.

Highway Barrier Solutions, the countryís leading steel barrier erector, again provided Extrudakerb with valuable local assistance and guidance as well as construction of the insitu concrete foundation slabs and light column build out reinforcement.

Highway Barrier Solutions also provided steel barrier in the verges and across Greencastle Bridge where loading capacity precluded the use of concrete barrier.

Our partnership with Highway Barrier Solutions grows from strength to strength and now includes concrete barrier installation on the A2 Sydenham Bypass and the A1/N2 Newry to Dundalk cross border motorway. The blend of two specialised concrete and steel barrier contractors with the added benefit of local knowledge and reputation has become an unbeatable combination.