By Tom Geoghegan
BBC News Magazine
Motorists in Samoa have switched the side of the road they drive on, overnight. It's a move that Britain has considered - but how would it work?
It's the kind of interview question that has reduced confident job seekers to quivering wrecks.
Imagine you are the minister in charge of the UK's roads and you have to switch the country to driving on the right-hand side. How would you do it?
A study of Samoa, in the South Pacific, this week might offer some clues. The country is experiencing its first day of driving on the left on Monday, the start of a special two-day bank holiday to ease Samoans into the new regime.
WHY THE RIGHT/LEFT SPLIT?
In the pre-industrial era, horses kept to the left so riders could draw their sword
Napoleon changed Europe to the right
The US followed France
But British influenced India, Pakistan, Australia and the Republic of Ireland
What if the UK were to follow? Driving on the right would make trips to the European mainland easier, when taking or hiring a car. And cars with steering wheels on the left could be cheaper.
The idea is not as fanciful as it sounds. Although the Department for Transport says it has no plans to change, it did examine such a plan in the late 1960s, two years after Sweden successfully switched to driving on the right.
Its report rejected the idea on grounds of safety and costs. But that was before Britain's entry into the European Union and the opening of the Channel Tunnel, which for the first time established a land link between Britain and the Continent. So, if the UK was to think again about a switch, what would be the key issues?
SIGNS & JUNCTIONS
Road markings and roadside signs would have to be switched to the other side of the road, but ready in advance of the day of change, in a huge logistical exercise.
One-way streets would have to be reconfigured and traffic lights with filters changed, says Paul Watters of the AA. To get an idea of the cost, changing signs from miles to kilometres alone was estimated at £750m, he adds.
Japan is also left-hand side
The biggest engineering issue would be highway building, says Benjamin Heydecker of the Centre for Transport Studies at University College London. About one in 10 motorway junctions is asymmetric or incomplete, so would need to be dug up and rebuilt.
"Motorway signs would have to be turned round and repositioned, so approaches to junctions would not be in the same place."
Accident blackspots would all need looking at too, because the signs there are site-specific and so would need to change.
ADJUSTING SLIP ROADS
"Entrance and exits to motorways are not symmetrical either, so there would be consequences there too," says Mr Heydecker.
Slip roads that were deceleration lanes would suddenly be used for accelerating, so their lengths would need to be extended; and vice versa.
Although many motorists would be used to driving on the right - thanks to trips abroad - a comprehensive retraining programme would be needed, according to Mr Heydecker. Particular emphasis would be put on negotiating roundabouts (which would run anti-clockwise) and left-hand turns, which would require cutting across oncoming traffic.
After years of driving, habits are well entrenched and it might take more than a few lessons to get used to the new arrangements. But where could "learners" practise, before the switch?
CAR STEERING WHEELS & BUS DOORS
Making life even harder for motorists is the fixed right-hand driver's position of cars sold in the UK - suddenly drivers would find themselves further away from the centre of the road.
Over time British drivers would buy cars with left-hand steering, so they would be changing gears with their right hands.
The global manufacturing of cars would be simplified if all countries were to opt for left-hand steering, says Mr Heydecker.
"If cars were all manufactured the same way, it would reduce the cost of design and improve the quality of vehicles."
Public service vehicles like buses would also have to undergo a massive overhaul so that their doors were on the right-hand-side of the vehicle.
LEARN FROM SWEDEN
Preparations were made long in advance, says Niklas Stavegard of Motormannen, which is the Swedish Automobile Association.
WHY DID SWEDEN DO IT?
Sweden's neighbours drive on right
It already had left-hand steering
In 1955, 83% voted against change
But the parliament voted in favour in 1963
"All road signs were doubled, new signs on the right-hand side, which were covered until the day of the change. On the particular day, the left-hand side signs were covered and right hand side signs were used."
The change was made at 0500 on Sunday 3 September 1967. All private traffic was banned between 0100 and 0600 and there was a total stop on all traffic at 0450, with a countdown on the radio to 0500.
The speed limit in urban areas was lowered from 50km/h to 40km/h for a period of time after the change.
A majority of all cars already had the steering wheel on the left side, so no change was made to cars.
In 1969, the financial burden of making the switch was calculated by the government to be £264m - about £3.4bn today. But that would now be seen as a ridiculously conservative estimate.
"Since that time, the road network and the level of sophistication of the network and its controlling infrastructure has grown enormously," says a spokeswoman for the Department for Transport.
Additional costs would include all buses being changed, alteration to motorway entrances and exits, and traffic control systems.
"Casualties would also be likely to rise, and the current cost of a fatality is £608,580," she says. "This could be particularly true for elderly road users who are less able to adapt to changed conditions."
The Republic of Ireland, which has already changed its road signs from miles to kilometres, briefly considered this move to greater European integration last year, when a pro-Brussels political party suggested it. But it was swiftly rejected.
"When the question came up, it was followed by the question 'Is it needed?' and the answer to that was 'No', says Sean O'Neill of the Irish National Roads Authority.
Look left, no right, no wait!
"If it was needed or if the UK did it, and left us as one of the last European countries driving on the left-hand side, then we would think differently."
For a significantly bigger country, like the UK, with a relatively more developed road network, the challenge would be even greater.
The immediate fear would be of road chaos and mass casualties, says Philip Gomm of the RAC Foundation.
"Given that any change would have to be instantaneous, and the nation's roads are never quiet, only less busy - indeed Britain has some of the most congested roads in Europe - how do you seamlessly get everyone onto the other side of the carriageway?
"The whole concept is mindboggling. It would be a logistical nightmare involving huge public education, vast sums of money and a massive amount of staff - and all so we can be like the French.
"So probably the best advice to anyone even contemplating such a scheme is; don't bother. If it ain't broke, don't fix it."
Additional reporting by Finlo Rohrer
Below is a selection of your comments.
You have to drive on the right when using the the short stretch of (public) road leading from the Strand up to the front of the Savoy hotel in central London. I was once told it was the only such road in Britain, and was something to do with taxi turning circles.
Chris H, London
The concern would be how it is funded. The driver is already heavily taxed and no doubt the taxes would be increased to fund this, even if the decision is not their own. However, car manufacturers continually state the cost of UK cars is because of making right-hand drive versions (even those, strangely, designed and made here) so we may be able to get cheaper cars here, or if not the penalty for buying abroad and bringing back here will no longer be that the steering wheel is on the wrong side.
Neil Hamshaw, Norwich
Rather than thrown £billions at changing sides, please can we throw £billions at vastly improving public transport, so that the roads are less congested? Then, in years to come, perhaps it won't be such a big deal.
Jerry Cullum, Alton, UK
To get the UK to drive on the right would be expensive, disruptive, unpopular and dangerous. So, it's quite surprising that the government hasn't tried to enforce this already. ID cards anyone?
Several road sections that come to mind that would be difficult to re-engineer are Spaghetti Junction, parts of the M2 which have extremely small acceleration/deceleration zones for slip roads and of course all of the variable speed limits on the M42, M6 and M25. Those would definitely not be cheap to sort out. The rest of it shouldn't be too hard I'd have thought.
Alex, Birmingham, UK
As usual, moving to the right seems to have high costs and few benefits. But for much less investment we could sort out our ridiculously muddled measurements. We buy petrol in litres but quote MPG to advertise cars! We buy UHT milk in litres, but fresh in pints! Completing the botched metrication programme would deliver real, affordable benefits.
Chris Edwards, Winchester, UK
As in so many things, Britain remains a floating heritage museum of the absurd, forever trapped in a pre-industrial era of quaint practices and bizarre traditions. Will we ever drag ourselves into the 21st century?
Steve, Suffolk, UK
When we drive from the UK to Europe the changeover occurs when we leave the ferry/train terminal. Would it be reasonable to suggest that we move the changeover point further and further inland starting at ports where you can drive into, to get to Europe or away from out of Europe. The transition then could be staged over a period of, say, three years.
Paul Gibbons, Milton Keynes
My brother lives near Germany and had noticed that there seems to incidents almost every month of Germans driving down the wrong side of the Autobahns. He now reckons that it's more natural to drive on the left. The rest of Europe should join the majority (of population) who drive on the left.
Peter S, Sandy GB
What would be gained from a switch? The traffic congestion would be just as bad, just on the other side of the street. Although it would be enormously amusing if Ireland made the switch and we didn't. The cross-over at the roads bordering Ulster would be the most chaotic places in the world. I'd be quite happy with metric distances and speed limits. Let's make the speed limit on motorways 80mph so we'd be ready for the (almost) European wide 130kmh limits.
Dougie Lawson, Basingstoke, UK
Having driven overseas on the 'other' side of the road, I will only do so in a left hand drive car - sightlines are wrong if you try to drive on the right in a right hand drive car.
Megan, Cheshire UK
Great idea which is well overdue. With increased international travel over the last few years many people will be quite experienced at driving on the right - Europe and USA being the 2 main overseas holiday destinations. I have driven on the right overseas for almost 30 years and have no problems whatsoever with adjusting the mindset to being on the "wrong" side of the road. In the long term the roads would become safer for both people in the UK (overseas lorries are a current problem) and for other countries (UK citizens more used to driving on the right). This is a task which is crying out for the EU to get to grips with - perhaps they could assist with both financing road changes and with subsidising people switching to left hand drive vehicles.
Simon in Leigh, Leigh on Sea, Essex, England
Everyone drove/rode on the left until the left-handed Napoleon Bonaparte changed it throughout his domain. Therefore, historically speaking, it is the rest of the world that has got it wrong! Changing now would be a huge waste of public money, be almost impossible to implement and cause many extra fatalities, for little gain in practical terms. Now Samoa has changed to the left, there are 75 countries who drive on the same side as us, so we are hardly on our own. Common sense dictates we should leave well alone!
Simon, Shropshire, UK
All sounds a bit pointless and expensive...but if we were given two extra bank holidays to get used to it like the Samoans (possibly continued every year to mark the momentous change) then it would certainly get my vote.
Pamela, London, UK
Driving on the left hand side is an anomaly that has become more significant now Britain is no longer an island, but the expense and expected high accident rate that can be expected if there is to be a change, would surely mitigate against it. For Ireland, and Malta who also drive on the left, there is no real incentive to change, as they are still islands with no direct connection to the rest of Europe. However, considering that all public service vehicles and many road layouts would need reconstruction, and the number of drivers who would need retraining, it is almost uncontemplatable. It really cannot be compared with the almost painless way it was done in Sweden, as the UK has a far greater road mileage and a considerably higher number of vehicles than Sweden in the 1960's.
Alex Gordon, Ipswich, GB