Premier Pits were appointed in October 2016 to install a prefabricated vehicle pit. The original scope was to install the pit with in situ reinforced concrete. However, our client, who worked with us before installing vehicle inspection pits, discussed with the end user the benefits of prefabrication off site.

The client was faced with a challenging below ground structure. They highlighted the railway inspection pit as high risk on their risk register. It was on their critical path and therefore any delay on site would impact the end date. There was also a tolerance in the specification of +-5mm which they were unsure they could construct with insitu concrete. Not only this but they faced a skilled shortage of subcontractors who had the ability to construct this type of below ground structure in an on-site environment.

To mitigate the risk, they approached Premier Pits to investigate a prefabricated off-site approach. We collaborated with Buckingham Group and gave them a product with was commercially competitive with in-situ poured concrete short term. However, gave the end user a far superior product long term due to it being watertight, maintainable, cleaner and safer to use. It was also installed in 2 weeks reducing their anticipated programme time by over 6 weeks. The product is also fully painted and has LED lights making this an excellent working facility for their engineers.

A satisfied main contractor and end user to have this facility, with cost, quality and time certainty during the build.

“We have worked with Premier Pits on several road vehicle maintenance pit projects and are therefore fully aware of all the benefits of prefabricated pits built off-site, this method of construction saved us considerable time on site and leaves the client with a far superior end product”.

Nigel Graveson, Project Director for Buckingham Group

To install prefabricated steel maintenance pits for the passenger transfer system at Heathrow’s Terminal 5.

The pits had to be installed 12m below ground level without interfering with other ongoing construction work. Also, the pits had to allow for free access along the length of the pit when in day to day use.

Due to restricted site access, the pits had to be designed in 8 metre sections prior to manufacture at Premier Pits’ factory in Spalding. They were then delivered by road direct to site. On arrival, the sections were offloaded and lowered by crane in one movement through the terminal roof, into position 12metres below ground level. Here they were bolted together to form 54 metre long water tight pits.

The problem of continuous access was answered by designing supports that only projected halfway across the width of the pits.

Both pits were installed within 10 working days during which there was minimum disruption to other construction work. The pits are now operational and are playing a significant part in improving maintenance efficiency and staff working conditions.