Tube contractor Metronet and subcontractor Balfour Beatty Rail are about to embark on a five month blockade on London's Waterloo & City Line (WCL), during which track and signalling equipment will be completely ripped out and replaced.
The line dates from 1898 and runs between termini at Bank and Waterloo. 'The condition of the track in some places is not so good, ' notes Metronet WCL programme manager Jack Carter. Currently there are speed restrictions down to 16km/h in some locations.
Since no other lines connect with it, closing down the line for a long period of time is relatively straightforward, Carter says. 'Instead of replacing [discrete] sections, we've taken the decision to replace the whole lot, ' he explains.
Balfour Beatty Rail LU services will be carrying out the replacement work and will also optimise the rail layout so that trains can ride around curves more comfortably. The work has been driven forward by London Underground (LUL), with the aim of providing Londoners with a more reliable and frequent service. The project also involves updating the signalling equipment so that trains can run at shorter intervals and negotiate the crossover at Bank at higher speed.
Had the work been carried out during weekend possessions only, it would have taken 87 weekends for the improvements to take place.
'Doing the work in a blockade, we obviously make savings because we can do the work more efficiently and there isn't as much time spent mobilising and demobilising workers and equipment, ' says Carter. It also eliminates the inconvenience of weekend engineering work overrunning into Monday mornings. The downside is that Metronet has had to pay LUL £3M for the privilege of doing the work in a block closure. 'So there is only a slight saving now, ' concedes Carter.
From 11pm on 31 March, work on the 19th century line will advance at full speed, with 4.3km of bullhead rails on longitudinal timber sleepers being replaced by flat bottomed rails on concrete cross sleepers.
With the new, more securely fixed track, trains will be able to travel at a constant 55km/h.
Computer simulations suggest that journey times will be reduced by about 80 seconds Access to the track will be via a service road at Waterloo Station and an access shaft halfway along the tunnel. The shaft will be used to allow the existing train fleet to be craned out and taken to a cleaning depot. Four battery powered locomotives will also be lowered on to the track to shift materials along the 2.2km long tunnels.