Essential Engineering

MQT on 2011-02-23
Session date: 
February 23, 2011
Question By: 
Richard Tracey
GLA Conservatives
Asked Of: 
The Mayor


For each year since 2000, how many hours of essential engineering works have taken place on the Underground network? By year, what percentage of this essential engineering work has taken place during the night?


Answer for Essential Engineering

Answer for Essential Engineering

Answered By: 
The Mayor

The majority of Tube essential engineering work is carried out during the four hours at night when the Tube is not operating; with an average of around 1,000 separate teams (or 7,000 people) currently booked each night to carry out this work. This means on average around 28,000 person hours of work per night and around 10.2 million person hours per year for the whole network. However, given the scale of this work no one single record exists detailing the exact number of hours of essential engineering work that have taken place for each year since 2000.

Due to the wide range of different work that is carried out during weekend and blockade closures (and the different numbers of staff involved depending on the type of maintenance/upgrade work), it is not possible to quantify the number of hours in a way which compares directly to those carried out during engineering hours. However, the simple numbers of line closures during weekends have been as follows:

2005* - 142 2006 - 186 2007 - 160 2008 - 166 2009 - 239 2010 - 227

In addition, three significant blockades have taken place since 2005:

2005/2006 - 518 days (Heathrow Terminal 4) 2006 - 164 days on the Waterloo & City line 2010 - 23 days on the Hammersmith branch

*Figures dating back beyond 2005 are not available.