For those not familiar, the way this works is rail cars roll in loaded with explosives, and they're unloaded into concrete magazines located in the channel.

The channel is designed so that if there's an accident, the explosion from the rail car is mostly directed upwards and not into the surrounding area.

This particular example is from Port Chicago, CA, a WW2 ordnance transfer station that suffered a massive explosion in 1944. Not far (but not photographed due to security) are revetments that were used in the Cold War for nuclear weapons transfer (essentially larger, more concrete, large numbers....and probably useless).