Sending out all the right signals

In 1868, railway engineer JP Knight invented the first traffic signal - a revolving gas-powered lantern with red and green lamps - near London's House of Commons, to regulate the flow of horses, carts and pedestrians clogging up the road.

Before there were cars, there was the traffic signal. In 1868, railway engineer JP Knight invented the first - a revolving gas-powered lantern with red and green lamps - near London's House of Commons, to regulate the flow of horses, carts and pedestrians clogging up the road. Since then, drivers have witnessed many signal variations and, surely, enforcement officers have seen their share of red light jumping.

In the UAE, 8,423 people were caught jumping a red signal in the first four months of the year, and there were 166 accidents that killed 285 people. The authorities in Abu Dhabi deserve credit for taking action, both for installing more red light cameras and for the deployment of flashing green lights they say are meant to give motorists a three- second warning that the "green phase" is ending. Data released last week by the municipality showed a 38.6 per cent decrease in violations at the intersection of Zayed the First Street and Bani Yas Street in the 32 days following the installation of the flashing green signals compared with the previous 32 days. Dubai launched a similar project in 2007 and motorists can still encounter flashing green signals on some streets there.

However, anecdotal evidence indicates motorists are confused about the meaning of the flashing green signals, with some carrying on through the intersection while others jam on the brakes the moment the lights start flashing. A simpler solution for resolving red light running at black spots might have been to increase the length of the amber light. That was certainly the case in five cities in the US State of Georgia, where a state law saw the length of the amber signal increased by one second above the national average. The result was a nightmare for the red-light camera companies, as red signal violations were virtually eliminated, according to a report in March by the Atlanta Journal-Constitution.

Also, research published in 2004 by the Texas Transportation Institute showed that, when the amber change interval was one second above the Institute of Traffic Engineers (ITE) minimum standard, red light violations were reduced by 53 per cent and crashes caused by running red lights fell by 40 per cent. When it was one second below the minimum, red light violations jumped by 110 per cent. Standards recommended by the Institute take many variables into account. For instance, according to ITE standards, roads with speed limits of 45 mph (72 kph) should have amber interval timings of 4.9 seconds, with the interval going up to six seconds for high speed roads.

In Abu Dhabi, where few motorists abide by the speed limit, city staff should run a survey to find the speed at which 85 per cent of motorists approach an intersection, and set the signal timing appropriately. Tougher enforcement of the posted speed limits would also help to reduce the number of red light runners. Of course, flashing green signals do give an extra three seconds before the driver must stop, assuming drivers understand what the signal is instructing them to do.

But since extending the amber signal time has reduced red light violations elsewhere, it seems it could have been a simple, easy to understand solution to Abu Dhabi's red light jumping problems. [e-mail]