Section speed enforcements gains global converts
First publishedin ITS International
The use of regular signs reminds drivers to adhere to the posted limit.
As the benefits of section speed enforcement are becoming clearer, the technology is gaining converts worldwide. Colin Sowman reports.
America’s National Transportation Safety Board (NTSB) is calling for urgent action from both road authorities and the federal government to combat speeding which has been identified as one of the most common factors in motor vehicle crashes in the United States. This new call follows the publication of a safety study which found that between 2005 through 2014, 31% of all traffic fatalities (112,580) were the result of crashes in which law enforcement officers indicated a vehicle’s speed was a factor. More than three quarters of crashes and fatalities involved passenger vehicles. While the relationship between speed and injury severity is consistent and direct, that between speed and crash involvement is complex and affected by factors such as road type, driver age, alcohol impairment, and roadway characteristics (curvature, grade, width and adjacent land use).
The NTSB report starts with the basics and questions the suitability of using 85th percentile speed of free-flowing traffic as the way of determining speed limits. It states ‘there is not strong evidence that the 85th percentile speed within a given traffic flow equates to the speed with the lowest crash involvement rate for all road types.’ Indeed it says raising limits to match the 85th percentile speed may lead to higher operating speeds, and thus a higher 85th percentile speed – effectively a vicious circle. It also highlights the availability of alternative approaches and expert systems that incorporate factors including crash history and the presence of vulnerable road users.
Significantly, it states that: ‘Speed limits must be enforced to be effective, and data-driven, high-visibility enforcement is an efficient way to use law enforcement resources.’ Furthermore, it adds that: ‘Automated speed enforcement (ASE) is also widely acknowledged as an effective countermeasure to reduce speeding-related crashes, fatalities, and injuries. However, only 14 states and the District of Columbia use it. Many states have laws that prohibit or place operational restrictions on ASE, and federal guidelines for ASE are outdated and not well known among ASE program administrators. Point-to-point enforcement, which is based on the average speed of a vehicle between two points, can be used on roadway segments many miles long. This type of ASE has had recent success in other countries, but it is not currently used in the United States.’
One of those other countries is the UK where the authorities are very keen on section or average speed enforcement and the use of this technology is increasing as the price of the equipment and communications continues to fall (see ITS International Nov/Dec 2016). Initially the systems were predominantly temporary deployments in work zones but having proved their effectiveness, the number of permanent installations is increasingly rapidly. One supplier, Jenoptik (Visyonics) has delivered equipment for more than 100 section speed installations covering in excess of 1,000km, and has orders for a further 20 systems.
Asfinag has found section control to be most effective
According to Jenoptik’s Geoff Collins, section-long compliance is a major advantage of the average speed approach. He points to ‘before and after’ speed measurements in Scotland where 112 cameras provide section speed coverage along 220km (137 miles) of the A9 trunk road (Europe’s longest average speed enforcement zone). He says: “I show this graphic and ask, ‘when do you think the cameras were turned on?’”
Most installations use paired sets of cameras with ANPR to time vehicles over a measured distance but non-linear areas and even small towns can be covered. “It is simply a case of speed and distance. If you measure the distance between two cameras, then you can set up an enforcement system,” says Collins, adding the qualification that they must be contained within a single speed limit. Siemens
has recently installed 120 of its Sicore ANPR cameras for speed enforcement duties as part of Transport for London’s (TfL’s) SafeZone roll-out. The cameras are permanently deployed in 80 sites on some of London’s busiest arterial routes. TfL’s head of strategy and outcome planning, Lilli Matson, said: “Ensuring speed compliance along a more extensive length of road, rather than just where a camera is located, can make a big difference in cutting the number of tragic, unacceptable collisions, saving more lives and improving air quality.”
Deterring, rather than catching, speeding drivers is a major attraction because average speed enforcement brings about a change in driver behaviour that extends well beyond the measured sections. Collins says that even after taking into account known statistical anomalies such as regression to the mean, average speed systems typically result in a 36% reduction in speeding motorists and often this behavioural change can benefit the surrounding areas outside the measured section.
Data from many sites shows that there is a 70% reduction in the number and severity of people injured in the targeted sections and the average 85th percentile speed of vehicles is just below the posted limit. According to Collins, “typically only one in 10,000 journeys will result in a ticket being issued” and he added that this level of income would just about cover ongoing maintenance.
“The big savings come from the reduction in crashes, crash severity and casualties and when those savings are taken into consideration, these systems can pay for themselves in six months,” he says. With the UK’s Department for Transport putting the savings for preventing a serious road casualty at almost £220,000 and around £2million for a fatality, it is evident that the benefits can rapidly repay the cost.
Regular warning signs, of which Collins recommends four for each camera, remind drivers they are in an average speed zone, help increase compliance and counter any suggestion that the cameras have been placed ‘to catch out drivers.’
The results of average speed enforcement on Scotland's A9 are easy to see.
, Austria’s state-owned motorway operator, currently has five stationary section control systems and 14 mobile systems (per traffic direction) near building sites. It has been using section speed control systems in high-risk roads (such as tunnels and work zones) for more than 13 years and has declared itself very satisfied with their effectiveness.
“Section controls help definitely to increase discipline inside certain sections. Their success speaks for itself - road users are much more disciplined in section control areas,” says Christian Ebner, head of traffic management at Asfinag.
“In 2013 we reviewed the use of ten years of section control in Austria. In all cases where we used section control systems, the number of incidents with damage to persons went down. This means that numbers of crashes in controlled sections have decreased by 50%.”
This is ‘decisively true’ for the system in use in the Bindermichl tunnel system because although there are still roughly 100 accidents per year, these are rear-end collisions with vehicles travelling between 40 and 50km/h and result in few, if any, fatalities. “There are no more accidents caused by excessive speeds – and therefore no casualties or hard crash consequences in the aftermath of high-velocity crashes,” Ebner says.
As an example of how section control systems can save lives, he highlights the Kaisermühlen Tunnel on the A 22 Donauufer motorway. Since the system was first commissioned in 2003, there have been no fatalities and crashes have halved. The effect in another tunnel at Niedernhart, near the German border, is even more impressive as the crash rate has dropped by two thirds.
With such proven effectiveness in combating speeding America’s NTSB is urging the implementation of average speed technology. It is calling on the USDoT to complete the actions called for in the 2014 Speed Management Program Plan and for the National Highway Traffic Safety Administration to identify speeding-related performance measures to be used by local law enforcement agencies. These, it says, should include, ‘the numbers and locations of speeding-related crashes of different injury severity levels, speeding citations, and warnings, and establish a consistent method for evaluating data-driven, high-visibility enforcement programs to reduce speeding. The performance measures and evaluation methods should then be disseminated to the local law enforcement agencies.’
Some of its strongest recommendations are to the 35 states that prohibit, or do not have laws regarding automated speed enforcement. To them the message is simple: amend your laws.