Yesterday, on my journey from Morecambe-on-the-mud to 'Orrible 'Orsham I drove down a section of the M6 where there were chevrons painted along each lane of the motorwy, and frequent roadside signs saying: "Watch your speed, Keep 2 chevrons apart" or words to that effect.
In this day and age, when there is a greater need for economy, I wonder why they wasted so much money, and effort, painting all those chevrons.
They could have painted the chevrons twice the distance apart and had notices saying: "Keep 1 chevron apart" - and either painted twice as many chevrons with the same amount of paint, or saved 1/2 the paint they used!
Some things just defy logic!
Some drivers can't count to 2 anyway.
I used to use that stretch of the M6 frequently. Before the chevrons there were loads of accidents as cars bunched up too close. The number of accidents reduced after the chevrons were painted.
My bro in law used to work in a department that did this sort of work, it's surprising the difference that putting two chevrons instead of one can make. To many people it might seem daft, to quite a few it's a visual warning and guide they can understand, to a smaller few they have no impact whatsoever - until those smaller few hit another vehicle and kill a few people.
Trouble is, like many things, once people get used to them they lose their effectiveness so no doubt sometime in the next five to ten years there'll be another method of slowing/controlling traffic.
Comes back to the age old question, what price life?
I'd agree that these garish markings do seem to be overkill.
However, there are some pretty thick people out there, and they need reminding.
If these markings save one life, then they are worth doing.
When you are in a car very near a road marking, you can't see the marking over the car bonnet. So if you should keep at least one chevron away, then to see the distance between this chevron and the one after it, you have to be yards before this chevron so you are (in a sense) too safe! So maybe one explanation is that doubling the chevrons makes it easier for you to judge how far apart the chevrons are. Also you get more opportunities to judge the distance when there are double the number of chevrons. (Tripling the number would make counting harder.)
Or maybe the authority that decides these matters has shares in the relevant paint company.
Distance between cars isn't the best measure. When going slower a shorter distance is safe; if the traffic was moving at just a few miles per hour, then keeping 1 or 2 chevrons apart would be ridiculous. I guess the distance between chevrons assumes that the traffic is travelling near the speed limit. And whereas thinking distance is proportional to speed, the braking distance is proportional to the square of the speed. (We'll ignore when the traffic is stationary.)
Recently I was told by a road safety expert that in good weather you should leave 2 seconds between your car and the car in front.
So authorities could replace chevrons by huge clocks by the roadside which reset when the rear of the previous car went past the clock. The clocks could be in the form of coloured lights, such as changing to green when the front of your car is more than than 2 seconds behind the rear of the previous car. In that case they should have shares in the relevant clock company. Pity it's impractical.
Many motorways eg M25 - now have lower mandatory speed limits of 40/50/60 mph - rationale being you can fit more vehicles in a given amount of road if bunched closer and slower - and thus get more vehicles through a section in a given time frame.