Blog Archives

"Yellow box" junctions

28/4/2022

After 1 June, councils outside London and Cardiff can apply to enforce moving traffic offences, such as driving through "No Entry", left- and right-turn restrictions, and stopping in restricted areas (so-called "yellow boxes") unless waiting to turn right with clear road off the junction.

Over half of drivers are generally in favour of enforcement, but the RAC has discovered that many yellow box junctions have design flaws, trapping drivers or making extent of yellow lines hard to see. Chapter 5 of the Traffic Signs Manual does not clearly state the specific purpose of box junctions or show how to design them to ease vehicle movements, and lacks maintenance detail. The RAC list flaws such as size, location, and visual obstruction for entering or leaving.

Some, of course, appear intended to allow traffic joining from a side-road to enter a queue on a major one, thereby contravening Rule 174 of The Highway Code. (See illustration of junction Warwards Lane / Pershore Road).

With thanks to The Graham Feest Consultancy.

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Under-used features of driving?

18/4/2022

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What's the second-most underused feature of driving? I think it's the brake signal. (Road position is the foremost).

Most people think the bright red lights that come on when you press the brake pedal, do just that. But they come on before.

So that you can warn following traffic that you INTEND to slow down, therefore they should let their own speed drop in order to keep further back, before you ACTUALLY start losing any speed.

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Efficient traffic flow ... at all speeds?

4/4/2022

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As more of us want to move about, what's the best way to get the most journeys completed?

Setting non-motorised travellers aside, and assuming a democracy (so, all non-emergency road users have equal urgency), vehicle interconnectedness significantly helps, even when only half of the vehicles share data about their states.

But, if there's no data-sharing, should we human drivers make different choices to achieve efficient flow depending on traffic density, say, on a motorway? It's the more relevant as "smart motorways" and active traffic management proliferate.

Lots of studies say we should all "zipper merge," or Reißverschlusssystem.

In this scheme, every car in the lane that's ending doesn't move to the adjacent one until the very end, then merging in turn with other traffic that's already there. This uses all available road space for as long as possible, cutting congestion by 40%, and reducing crashes since all traffic is slow when it manoeuvres.

However, driving habits are 'baked in', so most of us see it as pushy and unfair if others sail past when we've planned ahead and changed from our lane early. As one commentator has said "The zipper-merge is going to be this century's conversion to the metric system in the '70s. Great idea, made perfect sense, and was dead on arrival."

More theory's here. I'm awaiting pointers to further studies from Prof David Crundall, at NTU.

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