You may have seen my piece the other day about a cap over the M8; lots of people told me they support the idea, but the day after the piece was published, I got stuck, not for the first time, in the grind between junctions 13 and 18, and sitting there, stop-start-stop-start, the thought of changing the motorway, or improving it, or even mitigating its worst bits, suddenly seemed a bit hopeless. The lines of cars stretched out in front and they were telling me: it’s always going to be like isn’t it?

The main obstacle to the cap, I was told by the experts, is the bump in the M8 at the Mitchell. As you know, a train line runs under the road at that point and the council told me a cap wouldn’t be possible because of the limited headroom between the top of the railway tunnel and the bottom of a cap. They also said they couldn’t see the economic benefits to justify the price of between £50m and £80m or possibly more, and let’s face it: the cost of Barlinnie’s just doubled which is the way big projects seem to go in Scotland so it would probably be more.

But if you start by thinking that an idea is too much trouble, you’re always going to find reasons not to do it and the experts I spoke to said it was perfectly possible to overcome the raised section of road at the Mitchell. Hunter Reid, the architect who did the renovation of Maryhill Halls and protested against the M8 in the 70s, told me you could design a cap a couple of metres above pavement level. He also said the beams........

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