James Palmer, the Cambridgeshire & Peterborough Mayor has has dropped his election commitment for a light rail underground system for Cambridge and is now pushing for an articulated bus that can run in a short tube tunnel under the city centre calling it a Metro.

He reluctantly agreed with the Greater Cambridge Partnership (aka City Deal) to have the whole question of a mass transit system for the Cambridge area independently examined and alternative technologies for it evaluated. The report by consultants Steer Davies Gleave is due to be published in the New Year.

However Palmer went public unilaterally with a late draft of the report.  Leaving aside Palmer’s gross breach of protocol, the substance of the document shows why he has done this. Palmer fought his election campaign last May committing to implement a light rail system in Greater Cambridge. He was therefore dangerously committed to a particular outcome irrespective of what was feasible or affordable.

The draft report actually demonstrates that a light rail system is not the best solution; so Palmer got his defence in first by encouraging the public to believe that the option being suggested is really what he meant all along!  Spin in action!

The preferred option is an electric-powered vehicle which operates independently without tracks or rails and can be run on and off road on bus-ways.  The artist impression makes it look like a tram, despite having characteristics of a battery operated bus.   It reminds me of the Wright articulated “streetcar” bus.

The vehicle, which is being coined “CAM” (Cambridgeshire Autonomous Metro), can evolve to fully driverless as UK regulations allow. It could be based on technology already available in the vehicle market and there is much pointing to a similar system just introduced in Zhuzhou, China.

The report is likely to represent a very positive step forward, by potentially narrowing down options for a modern public transport network that could be supported by a medium sized city. There will be many issues to be addressed before we can say with certainty that this is the solution – and there may be downsides no-one has thought of yet!

Of particular concern are: how such a system would be funded; the full practical implications of tunnelling; how it would be accommodated on the streets when not in its tunnel – articulated buses are dangerous to cyclists; will there need to be more bus-ways and what supporting regime of demand management for road space would be needed?