It discourages traffic from entering a lane by promising to destroy the oil pan of any vehicle with insufficient ground clearance to get over it, making them similar in use (but not design) to rising bollards.
[2] The sump buster uses a non-mechanical solid mass of concrete, or sometimes other aggregates or metal, to demobilise a vehicle when access to a restricted area is attempted.
A major purpose of the sump buster is to avoid road systems to be used as rat runs and, to a certain extent, joyriding.
For this reason, devices have been vandalised (either through annoyance at their existence or to attempt to gain passage), resulting in accidents (and injuries) to legitimate road users.
[4] In January 2005, Devon County Council dismissed an application by the Stagecoach Group for the installation of a sump buster on Tan Lane (a restricted access road) in Exeter.