L9 Bar Mine

The L9 bar mine is a large rectangular British anti-tank landmine. The bar mine's principal advantage is its long length, and therefore its trigger length. A typical anti-tank landmine is circular, and a vehicle's wheels or tracks, which make up only a small proportion of its total width, must actually press on the mine to activate it. To increase the probability of a vehicle striking the mine, the mine's effective trigger width must be increased.
The bar mine's shape allows a 50% reduction in the number of mines in a minefield without reducing its effectiveness. It was reported that it would take 90 sappers 150 minutes to lay a 1,000 yd (910 m) mine field consisting of 1,250 British Mark 7 anti-tank mines, weighing a total of 17 tonnes. By comparison, it would take 30 sappers 60 minutes to lay a 1,000 yard minefield consisting of 655 bar mines weighing a total of 7.2 tonnes.
The long mines can also be laid through a simple plough attached to the rear of an FV432 armoured personnel carrier. Laying circular mines in similar fashion requires a far larger plough and more powerful towing vehicle. The bar mine laying FV432s were also usually fitted with launchers for L10 Ranger anti-personnel...