Fig. 98, which is a diagram of one of three arches used in roofing the train shed of the Sullivan Square station of the Boston Elevated Railway, is a good example of this type. This construction is the same in principle as that of the wooden arch shown by Fig. 59; it can hardly be considered as a truss in the ordinary meaning of the word, although it is a perfectly legitimate form of construction.
The arch proper rests on two 4 1/4" pins at each end as indicated in - the diagram, the tie-rods being connected to these pins. The bracing below the pins is riveted to the column and the arch itself is built of angles and plates with riveted connections. Fig. 98A shows the joint at A, where the tie-rods are connected and are held up by a l" suspension rod from the crown of the arch. A more complete description of this truss is given in the "Engineering Record" of June 15, 1901.