Spot speed deterrent proved to be transient

As research and trials show the benefits of average speed enforcement - David Crawford reviews developments on two continents.

August 2013 saw the switch on of the Australian State of Victoria’s latest combined point-to-point (P2P) average speed enforcement (ASE) and spot camera control system. Installed on the 27km Peninsula Link to the south-east of Melbourne, the system uses high-resolution automatic number plate recognition (ANPR) cameras and optical character recognition (OCR) technology developed by 112 Redflex Traffic Systems, which has its headquarters in the city.

According to the company the system is already operational on a 54km stretch of the Hume Highway north of Melbourne, making this the longest ASE in the world. Both have been commissioned by the Victoria Department of Justice (DOJ), the First Australian public authority to implement the technology.   

The Hume Highway network is the First such dual array to be implemented in Australia. The route runs for 880km between Melbourne and Sydney, serving the Australian national capital of Canberra on the way.

It is a major freight route linking between the three cities. The DOJ considers the stretch north of Melbourne to be among the most dangerous in the state, with its traffic mix of commuters, long-distance travellers and long-haul heavy commercial vehicles.

The system operates on four contiguous sections of the highway - of 24km, 15km, 8km and 5km - each operating independently with five camera sites in the highway median monitoring the speeds of all vehicles travelling in either direction. Each section’s length was determined by the number of intersections, to give restricted opportunities for vehicles to enter or exit midway and thereby avoid enforcement.

While the Redflex system can be triggered by lasers and radar, to comply with the DOJ’s requirement to make use of existing technology, in this case activation is by conventional in-road loop and piezo sensors.

Victoria state law also requires the deployment of two independent methods of speed measurement. A DOJ spokesperson told 1846 ITS International: “These checks and balances are in place to ensure the accuracy and reliability of the system”.

The AU$759 million (US$698 million) Peninsula Link serves as a continuation of the existing East Link, which connects with the city’s central business district, southwards into the Mornington Peninsula. A commuter zone, with a population of around one million, this is also a popular tourist destination.

Experience from Victoria has shown lower infringement rates in the longer sections. However, as has been shown in the US (see box) it also suggested a tendency for drivers to comply with limits when within a controlled section but to speed up once they feel that they are in the clear. It has also highlighted the importance of accurate verification of image matches.

An additional benefit is that the state police are using the data gathered to detect unregistered vehicles.

Increasing its investment in speed camera enforcement is a central plank of the Victoria Government’s 2013-2022 Road Safety Strategy. This notes that, following a dramatic fall in casualty numbers since the 1970s, the level has now started to plateau.

NZ experience

Across the Tasman SEA, the 6296 New Zealand Transport Agency (NZTA) has carried out its First trial (without enforcement) of P2P speed measurements using 4080 3M SpeedSpike equipment at a highway work zone with temporary speed limits in Auckland. The project presented particular challenges in terms of speed control.

The location was the 1.2km-long Newmarket Viaduct, which straddles a suburb to the south-east of the city’s central business district and is elevated by up to 15m above ground level. It was being replaced with a more earthquake-proof construction.

As the system was not intended to be enforceable, the NZTA-led Auckland Motorway Alliance (AMA) invited its construction and maintenance partners to volunteer details of their vehicles. If the system detected one of these as exceeding the speed limit, the AMA contacted the owner organisation.

An AMA spokesperson told ITS International: “By the end of the trial over 1,000 vehicles were signed up and there was a downward trend of speeding. A great benefit from using the average speed cameras was the availability of accurate information on traffics flows as the inductive loops normally used were not operational due to disruptions to the road surface and lane realignments. We are now looking at suitable locations to reinstall the equipment to monitor the effects of other roadworks on traffic flows.”

A recent research report carried out by consultants 3525 AECOM NZ for the NZTA sees advantages in P2P as encouraging compliance over greater distances that spot enforcement, and concludes that safety benefits observed overseas are likely to be replicated across New Zealand. Detailed analysis has identified 11 potential sites for its enforceable introduction.

Good practice guidance

Responding to growing regional interest in P2P, Austroads - the industry association of Australian and New Zealand road transport and traffic authorities - has issued a detailed ‘Research Report on Point-to-Point Speed Enforcement’. This sets out good practice principles as the basis for wider deployment in the two countries.

It notes that in both countries: ‘Speeding remains a major contributor to traffic crashes and related trauma despite enhanced road and vehicle engineering measures and increases in the intensity in which a wide variety of speed management approaches have been implemented.’

It reports that there have, as yet, been no formal evaluations of any implementations or trials in either country, with most of the available empirical research emanating from Europe – notably the UK, Austria, France, Italy and The Netherlands.

While noting the existence of ‘methodological limitations’ across the majority of these published evaluations, it finds that ‘the consistency of positive findings is encouraging’. Citing the Australian Government’s 2011-2020 National Road Safety Strategy, which stresses an ongoing need to manage driving speeds across the network, it welcomes the ‘considerable evidence’ indicating the positive influence of the approach on speed measures - average or mean.

Target cars at US work zones

Speed control strategies that specifically target passenger cars could increase safety in US interstate highway work zones, according to a recent report* from 4963 The University of Illinois. Its researchers have collected data from a test site on Interstate 55 (I-55) in Plainfield, in the State of Illinois.

They have analysed the effects on drivers’ behaviour of two alternative speed control treatments at road construction sites - one using a police patrol car, the other a speed radar photo enforcement system (SPE). These were compared with a base condition with no controls.

Following the passing of the Automated Traffic Control Systems in Highway Construction or Maintenance Zones Act, Illinois has installed SPE at a number of work zones.

The project collected data in two locations, one near a police car or camera and the other 2.4km (1.5 miles) downstream, to analyse drivers’ speed change behaviour when travelling between the two points. As can be seen in the table (right), the results of the paired observations suggest that the presence of a control treatment (police car or camera) had a noticeable effect. However it also showed that the vast majority of vehicles increased their speeds after they passed the police car or camera. 

In contrast to previous exercises, the researchers then analysed changes in the speeds of individual vehicles. Vehicle type proved to be a significant factor in the magnitude of change for both the treatment groups, with passenger cars speeding up more than commercial vehicles.

The researchers conclude that the police-based approach would benefit from the presence of an additional patrol car, on the basis that, after coming across one such vehicle, drivers did not expect to see another soon afterwards and so were tempted to speed up. By way of contrast many drivers were unfamiliar with the SPE and did not to know whether or not to expect a repetition.

Since passenger cars showed a larger average speed increase than heavy vehicles with either SPE or a police presence, the researchers suggest that targeting cars could be more effective in lowering overall speeds than treating both vehicle types equally.

* ‘Individual Drivers’ Speed Increase in Response to Speed Photo Enforcement and Police Patrol Car’, by Michael Lodes and Professor Rahim F Benekohal, of the Civil and Environmental Engineering Department of the University of Illinois at Urbana-Champaign.