Why encourage shockwave jams?

This is reasonably off topic, but it’s something we have all suffered from I’m sure.

Anyone who drives on any UK motorway has been involved in situations where the traffic slows to halt for no apparent reason. The reason for this is the shockwave jam. Until recently this has really only been a theory; modelled by mathematicians. Recently a Japanese team has managed to recreate the theory on a track.

We, therefore, now have a reasonably well established theory with an experiment and results.

So why do the people who look after the roads in the UK insist on creating so many circumstances where they encourage shockwave jams?

There are at least two sections of motorway near me where the road authorities have put on the road a set of very helpful arrows to indicate the safe distance between vehicles.

These are accompanied by a set of signs informing the drivers to “Keep apart 2 chevrons”.

I drive both of these roads quite regularly and whenever I am approaching these sections something happens. I slow down to a crawl, and regularly stop.

Why is this?

Because of a shockwave jam. Drivers approach the section too close together so drop back a little. That small action, on a busy road causes a shockwave which reacts back down the line of traffic until it forms a jam. The drivers within the chevron section may be safer, but the drivers approaching it are in more danger because they are bunched far closer together because of the shockwave.

The same thing happens as you approach speed cameras of which we seem to have at least our fair share.

I do have quite a lot of sympathy with the road authorities though. What are they to do? Am I expecting them to do nothing and let drivers go faster and faster and get closer and closer? No, I know that they have to do something. they have to remind us drivers what the safe limits are, because we need that reminder.

I’m not sure, though, that they do enough to protect us drivers as we approach these safety features, because the approach to them is the danger zone. I’m safer when I get there, but I’m less safe as I approach them. I’m not convinced that enough is done to try and avoid the shockwave and hence the danger.

One of the joys of working from home is that I don’t need to worry about such things because I travel to work by foot. If you want a bit of fun though you could always go and simulate your own shockwave jam.

One of the challenges of working from home is that my neighbour is building an extension and today seems to be angle-grinder day.