We all hate it when people zoom up the outside lane then cut in at roadworks. But should we all be doing it? Jack McKeown looks at traffic flow theory.
Roadworks. They’re a necessary evil.
The Tay Road Bridge was beset by them this week, with commuters enduring long delays.
Those of us who have to make that journey glumly take up a spot in the inside lane and settle in for a long wait.
Inevitably, some Johnny-come-lately will merrily zoom up the outside lane past all the polite drivers before cutting in at the front.
It’s infuriating. No wonder some drivers feel the need to straddle the white lines, blocking off such nefarious activity.
But are we causing ourselves delays by all diving into the left hand lane? At peak times traffic has been spilling back into Dundee, blocking in drivers who don’t even want to go to Fife. Meanwhile, one lane of the bridge where those cars could be waiting sits completely empty apart from the odd chancer charging up to the front.
Perhaps if we used both lanes, everyone would get home sooner.
At The Courier’s conference table, debate on this issue was more heated than it was over the referendum.
So we decided to consult the experts and lay the matter to rest once and for all.
We could not have opened a bigger can of worms.
Government bodies, quangos, and Britain’s most august motoring institutions are all at loggerheads over the issue.
Neil Greig is director of policy and research for the Institute of Advanced Motorists. He’s in favour of queuing in both lanes, but says the authorities should give clearer advice on the issue.
He said: “Rule 134 of the Highway Code does actually recommend merging in turn and the IAM have always felt it is an underused technique that would generate more capacity at roadworks by keeping two lanes full until the last few yards.
“BUT it must be backed up by clear signposting including the ‘zip’ merging sign and ‘merge in turn now’ plates.
“The traditional one lane closed ahead signs seem to have produced a generation of sheep-like drivers who get in lane far too early.
“This can be safer on high speed roads but on the Tay Bridge a merge-in seems an ideal solution. It just needs brave drivers to do it or a more innovative approach from the road works contractors!”
The AA, however, thinks using both lanes will never catch on.
Head of roads police Paul Watters said: “Zip merging can be efficient if everyone plays fair. It depends on how much stacking space there is and how disciplined drivers would be. It would be very hard to apply zip merging with any enforcement as there is no regulation for this. If the single lane queue does not back up, causing other problems, it’s probably better to not ‘trust’ driver interaction and stick with single lane.”
The RAC, meanwhile, sat on the fence. Spokesman Pete Williams said: “The perennial question of whether or not two lanes are better than one when it comes to queuing traffic is a topic which has vexed motorists and highway planners for years.” Surprisingly little academic research has been done on this topic, considering the potentially huge amounts of money that could be saved by cutting the time people spend in traffic jams.
One of the few pieces of UK research was carried out by Dr Guy Walker, of Heriot Watt University.
His study, published this summer, suggests traffic jams are 20% worse because British drivers are too polite.
He said, “My research found that the majority of drivers, when confronted with roadworks ahead, quickly move into the nearside lane as early as possible rather than merge at the forefront of the queue. No one wants to be seen by fellow drivers as the type of person who pushes in. This behaviour however leads to the loss of a further lane of capacity, that’s in addition to the ones already closed because of roadworks.”
But what does officialdom think? BEAR Scotland carries out the majority of roadworks in Scotland although it is not responsible for the Tay Road Bridge.
A spokesperson said: “In order to minimise queue lengths motorists should use all available lanes to maximum capacity then merge in turn once directed to do so. The priority at all times is the safety of workers and road users, we would urge all road users to drive safely and follow any instructions given.”
Dundee City Council, which has ultimate responsibility for the Tay Road Bridge repairs, also advised drivers to use both lanes: “We recommend motorists use all lanes available to them to maximise capacity and merge in turn,” a spokesperson said, adding: “We urge all motorists to take care during all road works and respect other road users”.
However, the Scottish Road Works Commissioner Elspeth King thinks deciding whether to use two lanes or one is a question of speed. The civil engineer said: “If it is slow or stop-start then queuing in two lanes and merging in turn would appear to be the most efficient method.
“However if the traffic is still moving, it causes less disruption to the overall throughput of vehicles if drivers merge earlier into one lane. This is because they do not cause the traffic in the open lane to have to brake to let them in at the point close to where the second lane is coned off.”
So there you have it. Complete disagreement.
One certainty is this: whichever lane you join, the other one will always move faster.