Complex work by Tube Lines to extensively modify the Piccadilly line signalling system and prepare for the line's extension to the new Heathrow Terminal 5 was completed on time, enabling services on the Heathrow loop to resume this week.
The station at terminal 4 has also been completely refurbished.Although the closure lasted 20 months, Tube Lines had just three months to undertake the intensive work after Heathrow Airport Ltd completed construction of a new junction to Terminal 5. Up to 120 experts worked over two shifts each day to install a new control system and update other systems. Installations took place at Heathrow, Hatton Cross and the line control centre at Earl's Court, where additional modifications were required to cater for the new line to Terminal 5.Key to hitting the project milestone was securing the approval for the safety case relating to the introduction of electrically controlled and detected points at the new Heathrow junction. The use of such a complex system on the Underground is unprecedented so the safety case had to be detailed and robust. The project involves some of the most complicated signalling work completed on the Underground since the opening of the Jubilee line extension in 1999 and required approximately 180km of new cabling in the tunnels connecting Heathrow to the rest of the network.In order to provide the most benefit to passengers, Tube Lines took advantage of the station closure at Terminal 4 to overhaul it. The upgrade means passengers are now benefiting from more information via new train indicator displays on platforms, new electronic information panels in the ticket hall, four help points and an improved public address system which enables digital voice announcements and includes built-in ambient noise controls so the PA can be heard as trains enter the stations. 179 speakers ensure announcements can be heard throughout the station.For increased passenger safety and security the station has been equipped with a new CCTV suite with a full DVD digital recording facility. Feeds come from 28 cameras.Improvements have also been made to the floor surfaces and tactile strips were installed to platform edges for added safety, especially of visually impaired passengers. The station was redecorated to make it look cleaner and brighter.