Fringe Box



Letter: Ash Crossing – Has the Cost/Benefit Been Properly Calculated?

Published on: 4 Jan, 2021
Updated on: 4 Jan, 2021

Ash level crossing

From Bibhas Neogi

In his letter Can We Really Afford This Bridge? Ray Rogers discusses how long traffic is held up at Ash level crossing and compares it to traffic lights at a crossroads.

If both roads have equal traffic flow, then each has 30 minutes of green light in an hour. A level crossing is similar to a road junction controlled by traffic lights but each time the barriers are down for about 4 minutes due to safety considerations.

So if there are four trains an hour each way, the barriers are down for 8×4=32 minutes. Traffic light phasing at a junction on the other hand maybe of 1-minute cycles, so the roads are open 30 times in an hour compared with 8 times at a level crossing. So the delay varies – 1 minute if caught by the red light at the junction or 4 minutes if stopped at the level crossing!

Traffic would build-up for 4 minutes due to a closed barrier and here lies the problem. The length of the queue would depend on the number of vehicles per hour using the road and pollution of noise and emission. Although these would decrease with modern technology, tailbacks may affect other roads and junctions.

Any improvement has to satisfy several criteria. Benefit has to be greater than cost. Environmental benefit is difficult to evaluate in monetary terms whereas removing delays and reducing accidents (if that is also a factor) can be relatively easier to calculate.

I assume the councils have done their cost-benefit analysis before promoting the scheme. Has the council clarified why the cost estimate has gone up from £15m to £26m? The question then has to be revisited as to whether the scheme still has an overall benefit. If not, it would be better not to proceed. The other question is shouldn’t SCC and not GBC fund the bridge costs?

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