Designed for congested/small UK streets where a lorry can't get up to significant speed. Also they are primarily deployed at the entrances to long walkways/bri

Designed for congested/small UK streets where a lorry can't get up to significant speed. Also they are primarily deployed at the entrances to long walkways/bridges, where a lorry at speed would do significant damage to pedestrians. As these prevent a lorry from entering a walkway, 5m of rapidly-slowing "penetration" is acceptable.