"In the following notes relative to the Economics in the Design of Bridges for Shop Considerations, the Drawing Room attached to the Fabricating Shop has been considered as a component and closely related part of the said shop; and points that facilitate the execution of shop drawings have been included.

"In the preparations of a bridge design for a given location, making spans duplicate instead of different lengths has not, in the writer's opinion, been given quite the attention it deserves. Such duplication always means decreased cost of drawings and shop work, and may mean also the adoption of a special fabrication programme for that contract, which would further reduce costs.

"For the same reason the design should lend itself to the maximum amount of duplication in the details. To this end small differences in the cross-section of main members should be shunned. The avoidance of light and heavy trusses, on account of a sidewalk on one side only, is a case in point. This, however, is more applicable to light work and to where the sidewalk load is comparatively small. Otherwise, where there is a material saving in weight by using light and heavy trusses, the difference can generally be accomplished by increasing the thickness of component parts of the various sections without changing the dimensions of the sections themselves, thus preserving the duplication of spacing and the details for the two trusses, as well as those for the lateral-system connections.

"Under modern mill and shop conditions it is economical to build bridges with longer panels than formerly used. Longer panels mean fewer joints and fewer separate parts, with consequent decrease in shop and drawing-room costs.

"If members can be made symmetrical about a point midway between the ends, it counts for economy in the preparation of drawings and templets.

"Often spans have been designed with a small skew where a nominal increase in length, due to making the span square, would have meant a decided saving in the cost of the structure as a whole.

"In the design of a deck-girder bridge, if the span is square, it is economical to arrange the lateral system with an even number of panels, so that the girder can be made symmetrical about the center.

"If the span is skewed, use an odd number of panels, so that the girders can be made alike and their position in the span reversed. Stringers without cover plates should have an odd number of panels of laterals. They will then have the same punching in the top flanges and be made alike for turning end for end, instead of different, as they would be if an even number of panels were used.

"Some Consulting Engineers and occasionally even the designing offices of the Bridge Companies are prone to make their designs so complete as to be almost shop drawings. This does not make for economy, either in