High-Tech Test Track
A skid to the left, and a swerve to the right… the vehicle stays on the road. It has been pushed to the limit and passed the test at the newly built section of the PSA Peugeot Citroen Group’s Belchamp test track, validating all the simulations done by the engineers on computers.
“We can use this new track to perform a full range of tests developed to assess vehicle behaviour,” explains Eric Fenaux, road performance coordinator. “Travelling at speeds of up to 170 km/h, the drivers here – all of whom are road performance experts – test their hypotheses in real driving conditions. Apart from bring specially trained in advanced driving skills, they also need to be physically fit and have full confidence in the accuracy of their calculations!”
“Track tests take up most of our time,” says Thierry Brasnus, a tuning technician. “Physical tests provide a complement to the numerical situation and are essential for calibration.”
He explains that most tests concern the behaviour of the vehicle – on all types of surfaces – and the behaviour of the person behind the wheel: deceleration on a bend, braking in a curve, and sudden swerving actions (such as the elk or moose test devised by the Scandinavians). Some of the tests are based on drivers’ subjective impressions which are considered just as important as the actual measurements because we also need to see things from the driver’s perspective.
“Ultimately, it’s the feel of the car that really counts,” stresses Fenaux.
The Belchamp facility is one of the Group’s many such facilities for testing future products. There are 30 kms of tracks at La ferte-Vidame as well as six endurance tracks and eleven development tracks (totalling 30 kms) of different road surfaces at the Belchamp Technical Centre alone. Like the test tracks of other manufacturers, its 450-hectare site is neatly concealed by surrounding forest to deter curious onlookers because there are often prototypes being tested and it obviously is not a good idea to have outsiders catch a glimpse of them before they are ready for presentation on the world stage.
In building the additional tracks for the Belchamp facility, the R&D staff saw a need to reproduce three different types of driving conditions simultaneously: wet surfaces, dry surfaces and black ice. This resulted in the layout of the track having two circuits, one set inside the other.
The first “wet” track is the main new feature, providing the technical centre with its own facilities to test vehicles in low-grip conditions. “Before, we had to use the Mirval track which actually belongs to our tyre manufacturer. The procedure was complex and involved a lot of forward planning,” says Fenaux. “There was a lot of logistics involved and we sometimes had to repeat the process of bringing the vehicles to that site and back again because the results were unsatisfactory. Testing could take up to 8 weeks – with no guarantee of a successful outcome.”
The new track is a valuable testing tool, and its 1.8-km length incorporates a highly original technical feature. Unlike a normal road designed for maximum grip, the surface is made extremely slippery – almost like a skating rink.
To provide such a surface required the contractor to undertake a lot of testing and develop a special compound which could guarantee a constant level of slip over time. Moreover, as its name implies, the track is wet all the time; a permanent layer of water between 0.8 mm and 1 mm deep covers it and the water is constantly replenished by a network of 2,300 spray nozzles. The conditions created are perfect for the test drivers who want to see what the vehicle does when it skids.
The new test track also has a 2.16-km section which is dry. Along two of its bends are glass tiles embedded in the road to simulate icy driving conditions. On this part of the circuit, the vehicle has to cope with two different grip levels which can be very challenging for the driver: the inner wheels roll on a stable surface while the outer ones skid on an ice-like surface.
“It simulates the sort of conditions which a driver will encounter when the vehicle hits a certain part of the road with black ice or veers off the edge of the road onto the slippery verge,” explains Fenaux. “This is the most extreme test of vehicle stability and the driver has to really keep his head.”
Now that such facilities are available at Belchamp, Fenaux and his colleagues no longer have to go far to do their work. “We don’t have to spend weeks on planning the logistics of external tests and we can make any necessary changes or adjustments to the tests without delay.”
The new track will also be used for other tests such as braking and tyre testing in association with other manufacturers.
