Bus trap

A bus trap (car trap in the UK) is a metal grate placed over a ditch or pit in the road with tines (sides) spaced far enough apart that small (shorter axle) vehicles fall between the tines but close enough that larger-diameter-wheeled vehicles, such as buses, may pass.

Many domestic vehicles exist in the 21st century wide enough to navigate bus traps effectively, including wide-axle SUVs and 4x4s.

Most cities favour other means of keeping cars out of bus-only areas, such as: The city of Calgary, Canada, began installation of bus traps in 1970s and primarily used them to restrict access to transit facilities and neighborhoods attempting to discourage pass-through traffic.

[1] The Cambridgeshire Guided Busway has numerous car traps, where they interact with road traffic.

[2] As a result, the council installed additional signs at that location with the hope to reduce the number of drivers ignoring and being trapped in them.