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Where to next in tolling technology? 10/2/2004
Whatever one's personal views about London's congestion-charging scheme, there can be no denying that it has and continues to have an impact on political thinking in Westminster and throughout the United Kingdom. The government has already introduced enabling legislation to allow local authorities to impose congestion charging schemes in England and Wales and, from 2006, is expected to launch a national distance-based charging scheme for heavy goods vehicles (HGV). This is likely to be followed by another road-user charging system for all motorists sometime after 2011. What are the practical and political implications for this policy? Is the available technology accurate enough and robust enough to handle the huge volumes of data that national schemes will require? Perhaps more to the point, is the technology accurate enough not to sink the whole idea before it has even begun?

Even with the current generation of tolling environments, problems continue to exist, including issues of accuracy, both in terms of detection/classification and enforcement. Others include the problem of performance degradation, caused either by adverse weather conditions or creeping deterioration in the equipment, over time. And while the advancing sophistication of software-based solutions have done much to minimise the risks inherent in inaccurate data, industry insiders readily admit they have not been wholly eradicated. Yet, unless they can be adequately addressed, the outlook for genuine open-road tolling such as is envisaged in the UK and elsewhere, looks bleak.

In essence, ETC (Electronic Toll Collection) systems are required to detect the presence of a vehicle, classify it, deduct the correct toll fee and, if necessary, enforce non-payment. In achieving this, a number of solutions have been proposed, all but one of which requires the integration of a range of technologies from companies like Efkon, Kapsch TrafficCom, Ascom and Q-Free.

On inter-urban routes, detection of the presence of a vehicle is generally performed either by an under-carriageway electro-mechanical device known as a treadle, or through the use of overhead or side-mounted light-curtains or ultra-sonic sensors. These trigger a short-range communications system, to read the vehicle's on-board unit and confirm payment. All are subject to performance degradation over time and/or under extreme weather conditions. In the high-speed conditions found in open road tolling, treadles are ineffective and side-fire, as opposed to overhead, systems will not deal with multi-lane environments. Moreover, the mechanical feature of the treadles make it inevitable that they will fail after a finite number of operations. This is usually in the order of one million activations - typically, once a year.

In urban situations an altogether different approach has been adopted. In London, for example, reliance is placed on computer software attached to CCTV cameras for the detection and enforcement process. The resultant back-office costs of the system are extremely high and London is presently looking to replace the system with more advanced technology.

For the future, there has been much talk of deploying GNSS (Global Navigation Satellite System) technology and other advanced systems of vehicle location for use in express tolling. But, self-evidently, such systems will still need a classification and enforcement arm in the event of non-payment.

What is required, is a system that is not only highly accurate under all conditions, including high-speed, multi-lane driving but one that is, at the same time robust enough to require little or no maintenance. Surprisingly, it seems that it is 'old' technology that may have provided the answer

Installed loops like those of MIDAS (Multiple Incident Detection and Automatic Signalling) and SCOOT (Split Cycle Offset Optimisation Technique) systems have been in existence for a number of years, dealing with issues of traffic management on motorways and urban streets. The Highways Agency has an ongoing programme of fitting the MIDAS system on all English motorways and SCOOTŪ and its various derivatives is in use in urban environments throughout the UK and a number of other countries. What has prevented its widespread use in electronic tolling, has been its relatively high error rate of around 1:100, which while statistically insignificant in traffic management terms, is wholly unacceptable in the tolling environment.

Huge strides in computer software technology over the past eight to ten years have allowed very high levels of accuracy to be obtained in the use of these loops, typically increasing the level from 1:100 to 1:10,000 error rate or >99.9%. Much of the credit for this belongs to Diamond Consulting Services, a small British company based in Buckinghamshire which has developed a series of complicated algorithms that are directly responsible for the improved accuracy rate. This advance, coupled with the replacement of the usual treadles and piezos, found in most tolling plazas, by electronic sensors, has meant that problems of wear and tear and the consequential reduction in, already low, data accuracy levels, have been overcome. The software-based IdrisŪ solution of Diamond Consulting will, it is claimed, last as long as the road surface under which it is built. It is also unaffected by weather conditions and capable of performing all the functions required of AVC (Automatic Vehicle Classification) within a single, integrated structure.

The point is of crucial importance not only for tolling operators but for policy makers as well. With the probable introduction of motorway tolling in the UK at some point after 2011, there is no question but that open road tolling, as opposed to tolling plazas, will be a requirement. If serious congestion is to be avoided - and this is likely to be the major plank of any political argument in support of the introduction of widespread tolling - there must be no delay to a motorist's journey caused by the need to collect the toll. But without the controlled environment of a plaza, any ETC system has to be able to handle not just detection, classification and enforcement but high-speed driving, lane straddling, tail-gating, signal over-spill (caused by larger vehicles hiding smaller ones within their electronic shadow) and stationary or slow-moving traffic.

Nor can there be any mistake in the classification process upon which is based the level of toll imposed. The light-curtain supplied by companies such as Austrian-based Efkon, is capable of providing up to twelve classification categories, based on the overhead 'view' of the vehicle supplied by the laser beam. What it cannot do, is classify a vehicle according to the number of its axles - a requirement that exists in a number of countries, including several states in the US. It is also, according to at least one source, subject to error in certain extreme weather conditions, including snow, although this is denied by Efkon.

So how do the new breed of installed loops work? Connected to a computer processor, a continuous stream of signal pulses, reads the changes in the inductance registered on each buried loop, as a vehicle passes overhead. The exact pattern of changes is then processed and converted into a unique line-graph that becomes, in effect, the vehicle's signature, capable of being precisely linked to a specific lorry or car. When read in conjunction with an in-vehicle tag, the system either allows the vehicle to go on its way or triggers an optional VES (Vehicle Enforcement System) camera and supporting procedure.

For payment and enforcement purposes, data from all the loops is immediately available to the lane controller processor. By analysing all loops simultaneously and comparing the vehicle's 'signature', it is possible to determine exactly what has transpired on each loop in the array. This provides precise and consistent outputs, regardless of traffic flow and environmental conditions, including queuing or slow moving traffic, and vehicles travelling in the wrong direction.

It is still too early to say what, precisely, the UK government has in mind in relation to its proposed road-user charging policy. The Secretary of State for Transport recently announced that the government was willing to begin thinking about the principles involved but the broad, technical parameters are clear enough. They include a high level of accuracy, free-flow express tolling and an environmentally friendly system that is economically sound and capable of producing much needed funds for the improvement of the infrastructure. The high maintenance costs associated with above ground ETC systems, coupled with questions on their reliability must raise questions about their suitability to operate cost-effectively under all operational conditions. Such considerations would seem to be unwarranted when considering installed loop systems such as Idris.

For further information, contact:
1. Max Staudinger of Efkon AG, Tel: #43 316 695 675
2. Teri England of Diamond Consulting Services, Tel:#441296 747 667, E-mail:
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