This article describes work undertaken to ascertain the commercial vehicle containment capability of a modified concrete barrier design. A modification of the British Concrete Barrier (BCB) is proposed which has a near vertical face, 800 mm high. The sloping face near the base was removed, which left a plane face sloping slightly away from the road at about 1.5 degrees to the vertical. The strength of the connection between each concrete unit was increased by inclusion of a bolted scarf joint. Impact tests were conducted with vehicles ranging from a 680 kg mini car to a 16 tonne lorry (HGV). Cars travelled at speeds over 113 km/hour and the HGV at 80 km/hour. All vehicles were fitted with triaxial accelerometers together with rotational rate sensors to measure yaw and rate motions. An instrumented 75 kg anthropometric dummy was calibrated and placed in the front passenger seat. An array of 10 high speed cameras supplied photographic evidence for analysis and documentation purposes. Impact tests at 113 km/hour with small (680 kg) and large (1500 kg) cars at an approach angle of 20 degrees into the barrier showed stable response during impact. The vehicles followed a low exit angle with good redirection close to the line of the barrier. Decelerations measured in the vehicles were compatible to those caused by impacts with shaped profile barriers. At 80 km/hour a 16 tonne HGV impacting at an angle of 15 degrees overturned after collision with the barrier. The fact that the HGV overturned upon impact with this barrier and not with a BCB barrier of identical height and under identical test conditions is attributed to the lateral shift of the concrete ballast block payload increasing the high roll angle present in all HGV tests. The barrier redirected the HGV and was not breached but the payload must be secure to reduce the risk of vehicle roll over.
Abstract