We need to plan the hard parts of a new transport system first

It’s easy to put off doing the difficult things. But the consequences can be unintended – even disastrous.

With a new transport system for Cambridge, the difficult part (certainly in terms of cost) will be the central section. Building underground tunnels – and especially stations – is expensive and slow.

Starting with the relatively easy bit outside the city means we’ll just be dumping people on the city fringe in five years’ time and only then facing the technical and financial challenges of the central section, which may take many years longer to complete. This is a very big risk. Even if we don’t start with the central section, we must at least have it designed before we agree to tarmac huge sections of the Green Belt and beyond.

Then there’s the untried technology which is envisaged. We have no idea if this bus-based vehicle can ever be safely authorised in the tunnel under the historic core, because the vehicle does not yet exist. We cannot run the risk of building busways outside the city, only to discover that the vehicles on them require larger tunnels which are too expensive, or cannot run in tunnels at all.

The risk can be cut with Light Rail Transport (LRT), which has proven itself even in the UK. Building tunnels for LRT track and vehicles in chalk or gault clay is straightforward. An underground station in the city centre and at the railway station will be needed, but with reduced car traffic, ‘green’ surface running should be possible elsewhere.

Within the city it isn’t speed but reliability and frequency that makes for quick trips. We know that LRT can provide this. Even at just 20mph, Eddington to the city centre would only be a little over 5 minutes compared to 25 minutes at peak time in traditional shared road traffic.

So before we agree to build busways outside the city, we must see detailed plans and costs for the route through the city core, and confirmation that the desired technology is suitable.

It would be irresponsible to leave crossing that bridge (or tunnel in this case) until we come to it.

This article was first published in the Cambridge Independent on 29 July 2020.