work; suddenly, there is an explosion. now, if there is an explosion, it will either be in the vehicle itself, or on the ground where the vehicle passes, or thrown at the vehicle when passing. those are the only options.
now, if it is in the bus, at least you can then set up a system where every bus will be searched properly before the soldiers board. if it is on the ground, then people will look and see things and report any unusual things. if it is to be thrown, then you will certainly be looking for people with either bulging pockets or arms ready to throw. in fact, you 