| Jefferson City Bridge, anchorage for draw-span | 124 | | |
| Jefferson City Bridge piers | 313 | | |
| Jefferson City Bridge triangulation | 324 | | |
| Joists for highway bridges | 214 | | |
| Judgment in designing, necessity for | 15 | 23 | |
| Kansas City & Atlantic Railway bridge | 114 | 135 | |
| K. C., P. & G. Railway bridge over the Arkansas River | 310 | | |
| Keyholes for hand-levers of draw-spans | 211 | | |
| Knots in timber | 299 | | |
| Labor-saving devices, use of | 13 | | |
| Lacing | 174 | 175 | 232 |
| Lacing, incapacity to carry transverse load | 26 | | |
| Lack of aesthetic treatment in American bridge designs, reasons for | 39 | | |
| Lack of economy in cantilever bridges | 55 | | |
| Lack of rigidity in cantilever bridges | 55 | 57 | |
| Lack of rigidity in suspension bridges | 57 | | |
| Lansdowne cantilever bridge | 67 | 68 | |
| Latches for draw-spans | 209 | | |
| Lateral bracing for highway bridges | 219 | | |
| Lateral bracing on curves in elevated railroads | 180 | | |
| Lateral struts, sections of | 171 | | |
| Lateral systems for draw-spans | 192 | | |
| Lateral systems, weight per foot of | 329 | | |
| Lattice girders, objection to | 19 | | |
| Laying out work | 328 | | |
| Layout of structure, general | 330 | | |
| Layouts for elevated railroads | 331 | | |
| Layouts for viaducts, economic | 87 | | |
| Least thicknesses of drums | 104 | | |
| Least thickness of metal in highway bridges | 226 | | |
| Legitimate and illegitimate decoration | 46 | | |
| Length of centre panel for draw-spans | 183 | | |
| Length of pin-plates | 14 | | |
| Lengths, effective | 145 | | |
| Lengths of base-lines | 322 | | |
| Lenticular arches | 83 | | |
| Lettering | 339 | | |
| Letting bridges by the pound | 139 | | |
| Levelling off tops of pivot piers | 195 | | |
| Levels in pier-sinking | 326 | | |
| Liberal allowance in estimating weights for details | 28 | | |
| Lift bridges | 108 | | |
| Lifting deck | 114 | | |
| Limitation of scope of all specifications | 15 | | |
| Limiting lengths of cantilever brackets | 226 | | |