[38] Table 1A. The count at Seventh Street bridge was recorded by different units and, therefore, required a separate table. The North Side approach to this bridge was being improved at the same time the count was made, causing a temporary interference with travel reflected in an abnormally small proportion of traffic on the bridge and a corresponding increase for the adjacent bridges.
[39] In estimating the gross tonnage, the following average weights were used: a street car with average load—19 tons; a heavy wagon (including team), averaging loaded and empty vehicles—4 tons; a light wagon (including team), averaging loaded and empty vehicles—1.75 tons; an automobile or carriage (including team),—.9 tons; pedestrians and passengers are figured at 150 pounds apiece.
[40] Estimating heavy and light wagons, including team and load at $125 per ton; carriages and automobiles, including teams, at $300 per ton; cars at $160 per ton and live stock at $200 per ton, we get an average tonnage value of $150 over the Sixth Street, Seventh Street[41] and Ninth Street bridges, and $125 over the Sixteenth Street, Thirtieth Street and Forty-third Street bridges.
[41] The figures for pedestrians, passengers and general tonnage are taken from the affidavit of John C. Perrott. The tonnage of mail was obtained from the report of the U. S. Post-office Department.
[42] See Note under Table 1A.
[43] The following data as to weight of vessels was kindly furnished by Mr. J. F. Tilley:
| Medium tows | 800 tons |
| Pool tows | 175 tons |
| Barges | 55 tons |
| Coal boats | 105 tons |
| Flats | 30 tons |
In estimating we assumed the following average weights for river craft, based in large measure upon the above data:
| Steamboats | 225 tons |
| Coal boats and barges | 80 tons |
| Barges | 55 tons |
| House boats, excursion boats, yachts, and U. S. Government boats | 45 tons |
| Launches, skiffs, etc. | 1 ton |
| Motor boats and miscellaneous | 10 tons |
[44] See Diagrams 1, 2 and 3.