Saturday 4 December 2010

Suggested new signs for the UK: Mandatory minimum following distance

This is one of many quick articles to show some suggested new signs. The minimum following distance for vehicles are shown in this article. Typically whenever mandatory following distances would be shown, they would always have to be much longer than the typical stopping distance at a certain speed.

For instance, in the Fréjus Road Tunnel, the minimum following distance is 150m and the speed limit is 70km/h. By contrast, in dry conditions, the typical stopping distance in dry conditions is approximately 57m when a vehicle is travelling at 70km/h.

The two suggested new signs are shown in this article: Mandatory minimum following distance, and mandatory minimum following distance for LGVs over 3.5t.

Mandatory general minimum following distance is 80m

Mandatory minimum following distance is 70m,
for LGVs weighing 3.5t or more.

These type of signs are also yet more signs already used in continental Europe, where almost all nations are contracting parties to the Vienna Convention on Road Signs and Signals.

Because the signs would be mandatory if and when they are used, these should only be used if there is a serious safety issue by not maintaining the stated following distance, and that the minimum following distance needs to be greater than the standard following distance in normal conditions. These signs would probably need publicity before they get introduced, and the other thing to consider is how to make sure the correct following distance is always kept.

Furthermore, these signs should only be introduced where absolutely needed (for example in some long tunnels for all vehicles, or an LGVs only restriction on mountain roads), it is not necessary to install this type of sign everywhere, but for tunnels, mountain passes, and other places where maintaining the specified minimum distance will help improve safety there. If the safe stopping distance for the prevailing driving conditions is maintained (whether in tunnels or elsewhere), that will definitely help improve road safety.

The chevron markings can still be used to help all road users keep the specified distance if needed (which would require no change in some tunnels), or other alternatives can be used in the future (e.g. side markers, electronic sensors).  The sign which says "KEEP APART 2 CHEVRONS", in other words "2 chevrons is the same as the minimum following distance", could do with being made more graphical (one idea is that perhaps the text could say 2 chevrons = 100m for example).

Perhaps it would be easier to prescribe and introduce this type of sign (only where absolutely needed of course) after metrication, when it will be a lot easier to relate speeds in kilometres per hour, and distances in metres and kilometres, to stopping distances in metres. There is no harm in prescribing these minimum following distance signs, but these do not need to be used everywhere, only where they really can help improve road safety (remember that some UK tunnels have the worst safety records in Europe).

This article does not in any way detract from the need to reduce roadside clutter. This includes removing clutter on signs, removing unnecessary supplementary plates, or removing unnecessary signs where applicable). Metrication and making signs conform to the Vienna Convention is a great time to consider all these.

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