PIER 7 ASSET REPLACEMENT ROOF MAIN WORKS

Heathrow Terminal 3
Client:  HAL 
Main Contractor:  Mace 
Sector:  Aviation 
Steel:  225 te 
Completed:  2016
Location:  London 
Scope: Structural Steelwork
Ancillaries
Services:  Detailing
Connection Design
Fabrication
Site Installation 
Keywords:  Prefabricated Walkways
Handrail
Ladders
Safety Gates
Open Grid Flooring
Steel Stairs

Project Background

 
The client identified that the existing roof membrane to the Pier 7 passenger corridor serving Gates 13-22 had failed, leading to water ingress to the passenger walkway and imposing a safety risk to users. The Pier 7 roof housed extensive mechanical and electrical services, plant, and equipment (including AHU and ventilation ducts).

The client’s approach looked to incorporate improved falls for a more effective rainwater disposal system and improved maintenance access to all necessary areas, with the intent that further expenditure will not be required before the terminal ceases operation (expected 2030).

A traditional build was deemed unsuitable due to the continued internal and external operations of the building, and the very low loads that the existing structure was able to support.

Bryden Wood’s solution utilised off-site manufacturing to construct a new steel platform to the total 380 metre length of the Pier 7 corridor, for installation above the existing structure. The new platform had a total footprint of approximately 1,600 square metres.

Supply and Fabrication

 
We prefabricated folding cassettes in our Teesside fabrication workshop, to simplify the installation methodology and reduce airport Stand closures. A typical prefabricated platform section comprised a central 3.0 metre wide section with two hinged panels which, once unfolded and fitted with open grid flooring, allowed a total width up to 9.0 metres.

Our in-house management coordinated the surface treatment (galvanising and intumescent fire protection) along with the supply and installation of all ancillaries, including approximately 850 linear metres of permanent and temporary handrail.

Site Installation

 
We installed the support platform on top of Pier 7 entirely on night shifts.  We firstly installed stubs from the existing steel columns, requiring on-site drilling of the existing structure that often had critical live services connected, requiring precise onsite co-ordination and planning. Installation of the main steel platform then followed with associated bracing, frames, stairs, and access platforms.

Our Construction Manager for the project noted that the biggest challenge faced on site was lifting the platforms within the restricted airside location and night shifts. ”We had from 2230 to 0330 to get a 300t or 400t crane onto the airport, rig it up with full ballast, offload a platform, unfold it and fit it out with grating, lift the cassette into position, and finally de-rig the crane. A 400t crane would normally require 5 hours to set up on site.”

As a preferred supplier for Mace we participated in all Mace Health and Safety initiatives, including the use of the Yellow Jacket reporting system requiring monthly Directors Tours, fortnightly Health & Safety Advisor Tours, and weekly Site Managers Tours, all recorded on Yellow Jacket.