Dutch Ministry of Transport Begins Year- Long ISA Trial in Tilburg
IV Quarterly Issue #3
October 1999

Intelligent Speed Adaptation (ISA), considered a radical approach by some, is gaining in momentum in Europe.  Beginning in October 1999, a practical trial of automatic intelligent speed control devices will take place with twenty passenger cars and a bus in the Dutch city of Tilburg.  In response to an IVQ request, Lies Duynstee, project leader of ISA social research at the Directorate-General of Public Works and Water Management Transport Research Center in Holland, graciously provided the following article on activities in his country.

Beginning in October, a practical trial will take place with twenty passenger cars and a bus that have been equipped with ISA in the Tilburg district of Campenhoef.  ISA stands for Intelligent Speed Adaptation and is a collective name for systems in which the speed of a vehicle is continuously measured within a certain area.  If the vehicle exceeds the maximum speed, the speed is adjusted -- either automatically by the engine, or by the driver through the use of warning signals.  ISA Tilburg has adopted the variant in which adjustment takes place automatically.

Consistent with the government’s long-term safety policy, ISA is seen as a possible measure to improve road safety.  The practical trial ISA Tilburg is an initiative of the Ministry of Transport, Public Works and Water Management in cooperation with the city of Tilburg.  Within the Ministry’s Transport Research Centre (AVV), the project leader is Angelien Van Boxtel, with Lies Duynstee responsible for research components.

Nature of the Speed Problem

High speeds have proven adverse effects on road safety, energy consumption, and the environment.  A study of the costs and advantages of reducing the speed of passenger cars in the Netherlands led to the conclusion that maintaining the present maximum speed limits alone would result in a decline in the number of hospital admissions by 15% and in the number of traffic fatalities by 21%; and that fuel consumption and emission of CO2 would decrease by 11% and emission of NOx by 15%.  In the Netherlands these advantages would result in a communal savings of 520 million guilders ($250M) per year.

After years of active speed policy in the Netherlands, it can be objectively established that the ‘traditional’ solutions to the speed problem has reached its limits.  There is still a considerable percentage of drivers that exceeds the various speed limits, fluctuating between 30 and 50%.  Advanced technologies make it possible to examine whether alternatives can lead to a reduction of these percentages.  ISA could be such an alternative.

What is ISA?

ISA monitors whether the driven speed and the desired speed correspond with each other.  Information about the desired speed is stored in a geographic database onboard the vehicle which, through use of a Differential Global Positioning System (DGPS), determines in which zone of the map it is situated.  Another possibility is that beacons that are placed along the road transmit the desired signals to the car.  With either system, the signals are converted into an action aimed at the accelerator, and the speed of the car is adjusted relative to the set limit.  The trial in Tilburg uses the DGPS system; there are no beacons along the road.

There are three ISA variants:

• The closed variant — A forced speed adjustment in which the system intervenes directly with the fuel supply, making it impossible to exceed the speed limit. This variant can also be seen as the compulsory variant.
• The half-open variant — or ‘intelligent accelerator.’ If the limit is exceeded, the driver needs to use more force to push the accelerator. This involves so much effort that adjustment of the speed follows automatically. However, the driver remains in control of the system. The adjustment of the speed thus also has a voluntary character.
• The open variant — With this option the system does not intervene with the gas supply or the accelerator, but the driver is given signals when entering an area in which a speed limit applies. When the limit is exceeded the driver is informed on a display next to the speedometer, or through a continuous audio signal, or by a combination of both. This variant is in a certain sense also voluntary.

The ISA Field Trial in Tilburg

In 1997 a feasibility study was carried out by the Adviesdienst Verkeer en Vervoer (the MOT’s Transport Research Center) into the possibilities of a pilot application of ISA in cooperation with the city of Tilburg.  This has resulted in a rough description of a project considered feasible. In a follow-up validation exercise, carried out by Bureau Hofstra Verkeersadviseurs, a further segmentation was carried out of the study proposed by TNO, the Dutch organisation for Applied Scientific Research.  A small-scale initial trial was proposed, which led directly to ISA Tilburg.

Between October 1st 1999 and October 1st 2000, the inhabitants of the Tilburg district of Campenhoef will be given the opportunity to gain experience with twenty Volkswagen Boras, equipped with the closed (compulsory) ISA variant.  These vehicles will be pretested by, among others, the Department of Transport Industries.  For successive periods of two months an ISA car will be made available to a group of twenty Tilburgers.  A bus also will be equipped with the same system, so that drivers of the bus company BBA can gain experience with ISA.

When drivers of the cars or the bus exceed the speed limit that applies in and around the district, their speed is automatically adjusted to the right level through the fuel supply. The maximum permitted speed varies within the area, from 80 km on an approach road to De Reeshof district, to 50 km on roads surrounding the district, to 30 km in Campenhoef itself, and dead slow on the parking place in the neighbouring Heyhoef shopping centre.

Objectives of the Trial

ISA Tilburg’s primary objective is to examine in a practical situation whether Intelligent Speed Adaptation is a realistic option as an instrument for speed control, both technically and in terms of driver acceptance and public support. Research, therefore, will be carried out in two ways: through equipment-based collection of data during the trial, and through a socio-scientific study.

The technical functionality of the ISA system will be examined by analysing the data from the automatic data loggers in the ISA vehicles.  This information will be supplemented with personal input from the users.  This is arranged via the logbook for ISA drivers, and by a questionnaire entitled ‘Experience and Acceptance.’  Particular attention is paid in the questionnaire to the technical experience of the user.

Emission, energy consumption and road safety will also be deduced through about a hundred and twenty test drivers who live in Campenhoef; the pseudo-experimental group, consisting of other inhabitants in the district; a semi-experimental group, consisting of other inhabitants of Tilburg; and an outsider group, consisting of a representative group of inhabitants outside Tilburg.

How it Works

The ISA system applied in Tilburg uses an on-board computer. By means of DGPS, it can be established within a two metre range whether or not the vehicle is situated in an area in which a speed limit applies.  When an ISA vehicle drives into a pre-programmed area, the speed limiting mechanism is activated, using a predetermined speed as the desired limit.

The cars and bus are at all times linked on-line to a ‘nerve centre’ via the GSM (cellular) network. Accordingly, all test cars will need to be parked outside continuously during the trial period. The nerve centre manages communication with the test vehicles, including announcements of the status of the ISA system in the vehicle. If a hardware or software error occurs, this is immediately reported to the nerve centre, and a service engineer is sent to the car. The nerve centre also makes a link at regular intervals to upload and store data from the data logger. After verification of the input data, the data logger in the vehicle is erased.

[Top]

For More Information ...

... contact Lies Duynstee, Directorate-General of Public Works and Water Management Transport Research Center, at M.L.Duynstee@AVV.RWS.minvenw.nl.

[Top]