Physical barrier to prevent motor vehicles proceeding against one-way traffic, uses transverse rollers set in road surface and released to roll freely to deny traction to vehicle traveling against traffic

摘要

The barrier is formed by a flat box (H) containing a number of transverse rollers (A). The rollers can rotate in one sense only and are blocked in the reverse sense by a retractable catch. For vehicles traveling in the correct sense, the rollers are blocked, and the vehicle can freely cross. For vehicles traveling in the wrong sense the rollers run freely and the vehicle loses traction.