Bridge Destruction ------------------ Bridges are much hard to destroy than buildings, and this is for several reasons: [1> Most of the bridges to be destroyed will be far larger than the buildings. [2> They are built strongly, to last for long periods of time. [3> They have many reinforcements that are not visible. [4> Everyone realizes the strategic importance of bridges, therefore everyone should realize how well guarded they are. An important factor to bear in mind, when working on bridge demolition, is the extent of real damage desired. Total destruction of a bridge is useless, a waste of good explosives. It may even be harmful, since there may come a time when friendly force will need the use of that bridge. Bridge destruction should therefore be considered a tactical-delay operation. It will slow the enemy down, and cause them much expense and time to rebuild. Since types of charges differ for different types of brides, I will go into specific types of bridge demolitions. [Stringer bridges] are the most common type of concrete, steel, or timber bridges in existence. They are usually one or more spans, but this makes little difference in the actual placement of charges. If more than one span is to be destroyed, one should just copy the first placement on the second span. The stringer-type bridge is on basically two or three steel "I" beams, referred to as stringers. The obvious method is to attempt to sever these primary aspects of the entire structure. This can be accomplished by placing charges on either side of each stringer. Each charge should be tamped either with sandbags or a wooden brace. The result of placing all the charges on the same side of the stringer is the twisting and forced warping of the steel beams beyond any future use. When dealing with a bridge of this type which incorporates more than one span, place the charges along the joints of the stringer, since this is the weakest point along the line. A [slab bridge] is a simple structure, consisting of a flat slab of either concrete or timber held together in such a way that it forms one continuous slab, these are the easiest bridges to destroy, since all that is required is a diagnol line of explosive charges placed either under, or drilled into, the structure itself. If the charges are placed beneath the bridge, they should be attached by some means, and tamping should be used. The [T-Beam bridge] is very similar to the stringer-type bridge, except it is without the bottom reinforcements. This doesn't mean the T-beam bridge is any weaker or easier to destroy. This type of bridge is based on three or four concrete or steel T-beams, with a large slab of concrete covering them. The space between the T-beams on the underneath of the bridge is ideal for the placement of explosive charges, since 75% of the tamping has already been constructed, by the very nature of the bridge itself. This type of bridge may have more than one span but, since bridge- destruction is only a tactical-delay operation, the destruction of one span should be enough. If you wish to destroy more than one span, just repeat the same operation, on the second span, paying close attention to the joints. Like the stringer-type bridge, the charges are placed beneath the bridge, between the beams themselves. A steel or wooden platform should be constructed to so hold the explosives, and direct their force upward into the bridge. The [concrete cantilever bridge] is probably better known as a causeway. It is usually a very low bridge, with many segments or spans supported by a series of concrete columns. The same basic procedure should be followed as previously outlined, in that one should look for the weakest point in the entire structure, and fix the charges at that point. The weakest point in most structures is the place where two objects join, so the explosive charges should be placed along the joints of the separate sections or spans. Place charges of explosives at the foot of the corresponding column to insure destruction. The charges placed at the foot of the columns should all be tamped and placed on the same side of the respective columns, so as to encourage maximum destruction. This type of bridge has many spans, but usually it is only necessary to destroy several of the middle sections. All charges placed at the foot of the columns should be situated on the same side, so as to channel the movement of the destructive force in one direction. The [truss bridge] is usually used for railroad crossings, and is built of steel. This type of bridge is one of the strongest in the world, and offers many problems for the saboteur. The best method is to run several different explosions at thirty-minute intervals, to that one can see exactly what needs destruction, but this is not feasible for the guerilla operation. Be very careful when attempting a sabotage operation of this type, especially with a truss bridge, since, as it is a train crossing, it will undoubtedly be guarded heavily. [Suspension bridges] are, generally speaking, the largest bridges in the world, and accordingly the strongest. It is a good idea to allow yourself three of four separate charges with a time lapse between them. If this is not possible, concentrate your charges on the main cables, and the center section of the bridge. Six - no less important - charges should be placed on the two towers at either end of the bridge and tamped down. *************************************************