The Project

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

The Problem

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.


Two 54 metre pits manufactured from pre-formed mild steel, fitted with safety lights and anti-slip flooring with a durable paint finish.

Why choose a Premier Pit?

  • Structural Calculations for 20 tonne per axle in normal ground conditions, site specific when required, up to 50 tonne.
  • Jacking rail 150 x 75 PFC
  • Zone 2 lights – Flameproof twin tubed
  • Premier Safety Lights (Epsilon 05 Atex 1426 X) (Optional)
  • Armoured flex cable with zoned glands
  • Lights and cables attached to galvanised unistrut with a plastic fascia
  • Anti-slip steps, Elefant tread – Galvanised.
  • Handrail – Hinged or fixed
  • Galvanised step-up rail for aluminum step up platform to run on (Optional)
  • Integral sump fitted as standard, no pump.
  • Unique bond of steel to concrete – Solid. Lattice work, not sprags.
  • 10 year warranty on Premier Pits installation
  • First pit installed 35 years ago and still in daily use
  • All pits sand blasted to SA 2 1/2
  • Etch Primer 10 – 20 microns.
  • Top coat – ISO free 2 pack modified epoxy 180 micro DFT.
  • All staff employed directly.

Please note that not all prefabricated pits are to this standard

Want to talk to one of our team? Call us now on

+44 (0) 1775 821222