I believe that the car which is on the  bridge is going to the military base.The military base is a place were all of the soldiers live and were all of the jets,tanks cargo bobs and so on.On the bridge is a dog with a man who is dressed like a soldier and is most likely to be because what type of man would were army cloths in front of the military base with a dog guarding it.The reason why the soldiers are in front of the military base with a gun and dog is because they are trying to make sure nobody smuggles anything such as drugs,exploses because they may be planning on exploding the place and so on.