The introduction of dynamic speed limits in Abu Dhabi has been welcomed by road safety experts who described it as a positive step, but they remain hopeful it will pave the way for further improvements.
The system has been rolled out on Sheikh Zayed bin Sultan Street (E10), with speed limits fluctuating between 80kph and 100kph.
It will help reduce speed variability, improve traffic flow and enhance safety on one of the emirate's most important corridors, Dr Hamad Al Jassmi, professor of civil engineering and director of the Emirates Centre for Mobility Research at United Arab Emirates University, told The National.
“Sheikh Zayed bin Sultan Street has undergone several development phases over the last decade, transitioning from a four-lane to five-lane configuration to accommodate increasing traffic volumes. While this expansion successfully improved capacity, it came at the expense of shoulder continuity in certain locations, which introduced safety and emergency-response challenges."
Having conducted simulations of the effects variable speeds will have on the road network, he noticed “recurrent peak-hour bottlenecks and flow instability”, leading him to conclude that additional measures are still needed.
“Complementing the new variable speed limit system with selective infrastructure enhancements – such as improving shoulder continuity – would further strengthen safety, incident management and overall network performance,” Dr Al Jassmi said.
What prompted the decision?
Abu Dhabi Mobility said there are four reasons for a change in speed limit: adverse weather, traffic during peak hours, events and roadworks.
“With variable speed limits, we can attain a smoother flow and less congestion,” said George Yannis, professor and director of Traffic Engineering Laboratory at the National Technical University of Athens. “This is also a very good campaign and an educational measure, sending the message to drivers that speed should be adapted to the conditions of the traffic and of the weather, they should not aim always to drive at just under the speed limit.”
He added that it may take some time for drivers to adapt to the new system, and they will have to stay alert for changes. Dynamic speed limits were first introduced to Abu Dhabi in 2019 and are implemented for construction work, blocked lanes, adverse weather or accidents.
“There are enormous advantages to the system,” said Walter Viti, a road safety expert and director of Activiti Consulting. “It is becoming popular, but it's also becoming specific to a localised area. It is not a system that can be applied everywhere. It is to be assessed with feasibility and with cost-effectiveness.”
Speed cameras are used to fine motorists driving above the lowered speed limit in these zones. The guidelines state that “variable speed limits are enforced using speed cameras that can be adapted to activate at the reduced speed”.
“I have seen over-implementation of such devices favouring more revenue-raising or enforcement compared to road safety and traffic management. This is why I emphasise the issue of feasibility,” Mr Viti said.
Is this used anywhere else?
Spain introduced its first dynamic speed limits this year along a 150km stretch of motorway. They operate similarly to the system in Abu Dhabi, using AI to adjust the speed limit based on similar factors. Some sections of Germany's Autobahn also use variable speed limits.
Dr Justin Geistefeldt of the Institute for Traffic Engineering and Management at Ruhr University Bochum has implemented and researched these systems in Germany.
“There are only a very few experts that know how to run these systems,” he said. “Currently, we are discussing ways to use artificial intelligence to do the calibration without the experts. It's not only the technology in the field, it's also the intelligence of the algorithms.”
