Bus lanes provide just 0.5% of the economic benefits of the Milton Rd scheme

The contract to design the final schemes for the Milton Rd and Histon Rd has just been awarded to the engineering firm, WSP: another £656,000, on top of the £2m+ already spent. The outline business case for Histon Rd has not been published or scrutinised by the Greater Cambridge Partnership (GCP) Board or Assembly, which is more than a little odd. However, I’ve looked at the economic analysis for Milton Rd, and it contains some very interesting truths.

The first is that just 3% of the scheme’s benefits are attributable to buses running slightly faster, and 97% to people cycling more. Most of those benefits derive from people living longer, healthier lives, and being absent from work for fewer days.

The next largest category of benefit is ‘marginal external costs’ – the incremental difference it makes for everyone else if someone switches from driving to cycling. There’s a benefit to the environment in reduced CO2 emissions, but also to other drivers (and their passengers).

If one more commuter car on the road at 7am adds 2.5 seconds to the journeys of 5,000 people following after it, that is an aggregated delay of 3.5 hours. With a value of time of, say, £10/hour, multiplied over 240 working days, the driver of that car is responsible for over £8,000/year of time costs imposed on other people. If the driver switches to cycling, that external cost is saved immediately.

When I double-checked WSP’s external costs calculation against the Department for Transport manuals, I arrived at a figure four times larger – and large discrepancies with other figures too, which I’m happy to share if anyone’s interested. Using my figures, cycling accounts for 99.5% of the scheme’s benefits.

So, why bother with bus lanes? How much greater would the net benefits be if, instead of bus lanes, the space was used for wider footways, continuously protected cycleways, more trees and sustainable drainage?

GCP’s commitment to building bus lanes is also a sadly defeatist acceptance that its measures to reduce traffic into Cambridge will fail, and buses will continue to battle with cars through the city.

This article was first published in the Cambridge Independent on 16 January 2019.