CROST: on the track of affordable tramways

Talk by Lewis Lesley

UCL 4th March 2009

Costs too high

Infrastructure

The National Audit Office argued that the cost of new tramways in Britain is too high. It arrived at this conclusion after examining new schemes and tramway extensions on the Continent. The NAO claimed that on a like for like basis UK tramway schemes were twice as costly as those on the Continent. An examination of the Cross River Scheme promoted by Transport for London is also of interest here.

Throughout this time, there have been no major changes to routes or alignments, or the proposed service. The level of inflation in the civil engineering and construction industries has also been near the national level, at about 5%pa. Neither explains why Transport for London, consistently inflated, by about 40%pa, the cost of the Cross River Tramway.

The Millennium Dome transport link also provides another insight on the question of capital costs. This was supposed to have been a dedicated and guided transport link between Charlton Station and the Millennium Dome. Two options were offered:

• a. wire guided diesel buses (at £5m)
• b. conventional electric trams (at £10m)

The Wire guided bus option was selected, using a technology that had not been made to work anywhere else. In the end the wire guidance was abandoned but not before some £25m had been spent. The buses were manually driven on a short length of busway, as the Railway Inspector would not licence as safe the wire guidance system.

One of the issues for central London streets is that over 100 years, the under street space is congested with cables, ducts, gas and water pipes, drains and sewers. The street track used for the Croydon Tramlink has as its foundation a concrete slab 6m wide and about 400mm thick. Any under street utilities are then inaccessible for repair or maintenance. The Utility Companies naturally require their plant be relocated to accessible locations, and the tramway promoter pays 92% of the cost. The big issue in Central London is where can utilities be diverted, since there is so little space which is already congested ? Consultations with utility companies confirms that they would rather leave plant where it is because:

• a. their design offices are already busy in routine maintenance and development
• b. that relocation always creates secondary problems
• c. the interface between relocated (new) plant and old creates further problems

Some public sector tramway promoters have argued that removing the utilities means that tram services will not be disrupted by the need to maintain or repair under street plant. In practice a serious utility failure, e.g. gas leak or water main fracture would close a nearby tramway. Thankfully these are about once in 40 year events. A cost-benefit calculation shows that it is cheaper to have the tram service disrupted for a week every 20 years, than pay to remove plant.