Something completely different: ITS

Dubai's ambitious development includes an all-new Intelligent Transport System, or ITS to its friends. As any Dubai driver should have noticed by now, ITS manifests as a whole series of new gantries over the major roads that can flash variable messages in Arabic and English to road users. Part of the system has been put on to selected existing gantry signs, where the lack of spare space has restricted the new displays to lane arrows and speed limits.

According to one of my transportation spies, based on experience elsewhere on the planet the provision of ITS can reduce congestion by 15%. The idea is that by telling drivers well in advance about changes in the highway conditions ahead, they can get into the correct lane well in advance or possibly even take an alternative route rather than getting trapped in a traffic jam.

Another issue is variable speed limits. Although it appears to defy logic, reducing traffic speed from 120kph to 80kph actually increases the flow. Essentially, as we go slower we reduce our braking distances ('headway' in traffic engineer speak), so more vehicles go past per minute. One of the reasons for imposing lower speed limits through roadworks is to increase the flow through a reduced number of lanes. Naturally, another reason relates to the safety of the Boys In Blue.

So far the theory is fine. Operators continuously monitor the traffic using CCTV and detector loops, and with the help of computers the speed limits are varied so as to ease traffic flow. In extreme weather conditions, lower speed limits can be displayed to assist any drivers who are incapable of understanding that dry-weather speeds and stopping distances are inappropriate on slippery roads. If a lane gets blocked by an accident, breakdown or - perish the thought - a puddle, the green arrow can become a red 'X' to advise drivers to vacate that lane.

And in practice? This morning was typical: in the pouring rain, spray and generally foul driving conditions, the ITS signage continued with its 100kph clear road advice. Of course, 100kph is a limit, not a target. But in crawling traffic, how credible is that? On the Emirates Road last weekend in the rain, the large message signs told us to drive at 60kph, not 120kph, and to beware of standing water, yet the same system was simultaneously displaying a 100kph speed limit!

And I have yet to see a lane closed by an overhead display. It'll be as effective as a chocolate teapot. The only realistic way to close a lane is to block it with a uniformed officer of the law. And the best way of slowing traffic is to bend a couple of cars and then advertise them with some flashing blue lights. Everyone will inevitably slow down for a good look. There's never been a traffic accident in Dubai before...

If the variable message signs contradict each other, if they are never seen to vary, if the system is never seen to react to rapidly changing road conditions, will drivers simply assume that the ITS is an expensive system of illuminated signs that can, along with all the other street furniture, be ignored? Traffic police already have a difficult enough time enforcing traffic regulations. An additional system whose reliability no-one seriously believes will not make their job any easier. Without credibility, the ITS cannot perform a useful function. Without drivers' compliance, ITS cannot hope to deliver on its promises.