Originally, this maneuver was named “moose test” or “elk test” and designed to provide a criterion to prove the tilt stability of a vehicle.
In November 1997, the German automotive industry launched a safety initiative. One aim of this initiative was to simplify the criteria for testing the active safety of vehicles (driving dynamics tests). Uniform tests should provide comparable test results, thereby preventing possible uncertainty for consumers. The team of experts included representatives of the seven German car manufacturers, the insurance sector, the Automobile Club, independent scientists and representatives of test organizations and motoring journalists.
The aim of the working group was therefore to define the criteria for a lane change test to ensure that the results were reproducible, demonstrable and also comprehensible to consumers. Thus, the working group created the VDA test. The requirement level of the VDA lane change test had to be at least as demanding in all phases as the “moose avoidance test”, especially in the fields of steering effort, vehicle control and tendency to overturn.
VDA Test procedure
The VDA test procedure has now been published as ISO 3888-2.
What is the ISO 3888-2:2011 ?
ISO 3888-2:2011 defines the dimensions of the test track for a closed-loop, severe lane-change maneuver test for subjectively determining the obstacle avoidance performance of a vehicle, one specific part of vehicle dynamics and road-holding ability. It is applicable to passenger cars as defined in ISO 3833 and light commercial vehicles up to a gross vehicle mass of 3.5 tons.
VDA Test track dimensions
|Section||Length of Section||Section width|
|1||15.0 m||1.1 x vehicle width + 0.25 m|
|3||25.0 m||1.2 x vehicle width + 0.25 m|
|5||15.0 m||1.3 x vehicle width + 0.25 m|
|Lane offset = 3.5 m|
The time measurement is started in the entry lane and ends prior to leaving the exit lane. At the same time, the accelerator pedal is released in the entry lane so that the vehicle is moved through the course in power-off (deceleration) mode. This corresponds to the typical behavior of drivers. During the test, no traffic cones may be hit. Otherwise the test is not passed.
The entry speed measured in the entry lane is increased step by step, starting from 60 km/h until the car skids, hits cones, or spins around. This usually happens at speeds of about 70-80 km/h (45-50 mph) in the best cases. The tests are driven with and without ESP (Electronic Stability Program). ESP is used to avoid sudden overreactions of the vehicle (swerving).
During the test, significant movement parameters are measured and comparable evaluation criteria like maximum steering angle speed or maximum float angle are derived afterwards.
The relevant metrics for the VDA obstacle avoidance test are:
- Vehicle longitudinal and transversal speed
- Steering wheel angle and torque
- 3-axial wheel forces and moments
- Toe and camber angle as well as 3-axial wheel travel
- Vehicle slip angle
- Slip angle
- Pitch, roll, yaw and attitude angle
- Longitudinal, transversal and yaw acceleration
The roll angle that is present when the vehicle enters the first lane results from the configuration of the acceleration track vis-à-vis the cone-lined lane. The acceleration track is oriented toward the cone-lined lane at an approximate angle of 5° so that the driver has to provide a turn-in steering input which causes the respective roll angle. During the first directional change, the transversal acceleration is still almost in phase with the steering angle; later, a significant phase lag of transversal acceleration and roll angle occurs. Also, the delayed build-up of the vehicle’s slip angle is notable, which can be explained by the inertia of the vehicle mass.
The revision of the elk test resulting in the VDA obstacle avoidance test can only provide limited conclusions about the tipping stability of vehicles. Typically, the so-called “fishhook test“ is performed, in which the criterion of tipping is met when two wheels have tipped up simultaneously by at least 50 mm.
VDA test video
In this video you will see a vehicle during the VDA test with and without ESP.
To resume, to pass the test:
- None of the cones may be touched during the lane change test.
- The driver doesn’t have to touch the brake nor accelerator pedal.
- The vehicle speed has to be greater than 60 km/h.
Charlie Constant’s opinion:”
The « moose test » or « VDA test » is sometimes criticized because the steering wheel angle speed for the test is not realistic and because the brake pedal is not used (whereas a real driver would use it). However, isn’t it safer to have a vehicle passing a test more difficult than what happens in reality?