|
 previous / next column
A PHYSICIST WRITES . . .
(February 2016)
Early this month (February), news reports told us that in several parts of the country, certain resurfaced roads had been left without their central white lines, as an experiment. What triggered the reports was the announcement from one of the areas, Norfolk, that the scheme was about to be extended, “...including on the A148, close to the Queen’s Sandringham estate” – it’s not clear if this information was meant as a warning to us or to HMQ (or both). A council spokeswoman said that fewer road markings can improve street safety for everyone by making drivers more cautious, increasing awareness and lowering speeds.
Well, how satisfying it is to be able to say that you read it here first (ten years ago)! This is what I wrote in my May 2006 column: “The white line gives drivers far too much confidence that oncoming traffic will stay the other side of it. Vehicles are thus positively encouraged to pass each other, inches apart, at relative speeds of up to 120 mph (on out-of-town roads). The slightest lapse of concentration or twitch of the steering wheel can bring death and disaster. Centre lines should therefore be painted out, to force drivers to think about the inevitable hazards in two-way traffic and make allowances for them.”
Now you might say that a basic flaw in my proposal is that you can’t paint out a white line! I mean, whatever colour is put down over it you will still be able to see where it was. The advertised technique nowadays, however, is to use ultra-high-pressure water jets to remove the line completely (though if this works, it’s no wonder that new lines wear away as quickly as they do...).
But back to the recent news: the reports quoted an impressive figure of 13% for the reduction in average speeds, after the lines had gone. Then later I came across a Transport for London (TfL) report from 18 months ago, looking at speeds on three lengths of suburban A-road (all were uncluttered, so the 30 mph limit was often easily achieved) – before and after resurfacing plus widening of existing cycle lanes, and non-reinstatement of the white line and/or central hatching.
Average speeds were measured in each direction on each of the three roads: before the changes, five out of the six averages were above 30 mph. Afterwards, five were below 30. The reductions ranged from 3% up to 13%, and I suspect that the higher figure was the one that some of the media picked up and quoted as if it was typical, rather than the largest (average) that had been recorded.
But in fact the outcome was even more impressive than it appeared in the news: the researchers guessed that if a road is resurfaced and nothing else is changed, speeds are likely to increase, since drivers know their vehicles will have a smooth run. To confirm this, a fourth length of road was renewed with its white lines restored afterwards, to act as a ‘control’ for the other stretches. And the average speed did indeed go up – by about 15%.
Now assuming that this rise would have applied equally to the other three roads, the full effect downwards of removing their lines was presumably that much bigger (than the 3% to 13% observed)! And so finally, in the TfL report, the effective overall decrease in speed because of doing away with the lines was estimated to be 22% or around 7 mph. There may be one or two dubious logical steps here, but the general conclusion can’t be in doubt: centre white lines encourage higher speeds.
The big question, though, is whether removing them cuts the accident rate. The trials to date (even taken together) were too small-scale to answer this reliably, but it’s widely accepted that the number and the seriousness of accidents on any road are correlated with speed. And anyway, if drivers are not just going more slowly but also being more cautious and paying more attention, who can argue that taking the lines away won’t make roads safer?
Actually, quite a few people can! Here’s a spokesman for the AA, responding to the recent reports: “Authorities should be looking to increase road markings, rather than decrease them. They have a vital role in keeping road users safe. Unlike road signs, markings are already less intrusive but still help road users.” And this from the RAC: “Their removal would likely lead to an increased ‘fear factor’ of driving and accidents, for the majority of motorists who take confidence from clear road markings.”
The national director of the Road Safety Markings Association (yes, it really exists) said: “There is no proof that removing markings makes roads safer, or that drivers confused by a lack of clear guidance are somehow safer drivers.” A man from Brake (the road-safety charity) agreed: “The TfL data only seems to look at a possible reduction in average speed, and not the number and nature of any collisions.”
This is true enough. But the problem is that even though more than 1700 people are killed and more than 20,000 seriously injured on our roads every year, it would take a bigger investigation (than we’ve seen so far, I mean) to allow an accurate assessment of the safety benefits of removing centre lines, by possibly making a dent in these figures.
And first someone would have to decide which roads to investigate – busy shopping streets? Fast suburban roads (as above)? Winding rural routes? Regional single-carriageway A-roads, right up to a 60 mph limit? Any of these categories might prove to be more hazardous with the lines removed. Also, we can expect complaints from drivers who have already invested in a car with built-in white-line detection!
In any case, accidents would occur on the modified roads just by chance, leading to calls for the trial to be abandoned. Ten years ago I took the view that centre lines were a bad thing. Now I’m thinking that they might be better left as they are...
Peter Soul
previous / next column
|
