From December 2010, the Circle Line was extended to Hammersmith in west London using tracks shared with District, Hammersmith & City and Metropolitan lines.
The plan was developed to introduce a fixed terminus at Hammersmith to help improve reliability and capacity on the line and was the first phase of the Sub Surface lines upgrade, (which also includes a fleet of new air conditioned trains and a new signalling system).
As Howard Collins (the Chief Operating Officer) pointed out at the time; "The added benefit will be the improved service on the Hammersmith & City Line from Edgware Road round to Hammersmith, almost doubling the frequency on that route."
In late 2009 it became apparent that the train crew accommodation would not be able to be accommodated within station platform extension works then underway at Hammersmith with obvious LUL implications for capacity, revenue and reliability. wpa were asked to assist in devising a strategy to deal with the situation.
A rapid viability study revealed that two options were available; the construction of modular temporary accommodation on an adjacent carpark or the rapid procurement of a lease on adjacent shell and core office accommodation followed by rapid design, assurance, tender action and fit out. Wpa programmed out the options for the LUL programme team lead by Sherif Narouz who then drove the recommendation forward on behalf of the end user.
TfL group Property moved rapidly to secure a lease whilst wpa undertook due diligence on the building and building systems to verify existing building infrastructure and de-risk the remaining design and build phases.
The viability study had also revealed
1) The risks to staff of traversing the interface between the station and adjacent building
2) The issues that would arise for resilience in relying on the buildings central plant
The former meant that a complex and time consuming route appeared to be the only option for accessing the accommodation. wpa were able to overcome this challenge by means of designing a bridge connection between the existing station over-bridge and the new building.
The latter meant that wpa recommended a dedicated plant room be installed within the lease footprint; in-taking air through the skin of the building; this had the implication that fabric had to be carefully designed to limit acoustic attenuation to Gn32 to reduce nuisance for staff and fellow tenants alike.
Once heads of terms were agreed for the lease deal wpa proceeded rapidly to produce an assurance strategy for the works followed by a detailed design for fast track tender with associated tender information; necessary to tender under NEC 3 Option A.
Contractors Overbury won the tender for the fit out and proceeded to procure the required materials at a fast pace.
Simultaneously a contract was let to Cleshar Contract Services (a specialist rail contractor) to complete the design of the linkbridge and construct it.
Close management of the works meant that the fit out was delivered on time to quality within budget and that the Extended Circle Line was able to be brought in to timetable.