The few packet boats running on the river are of moderate height and can be accommodated in the harbor under the bridges at ordinary river stages. The amount of business that could be done by a few packet boats of extreme and unnecessary height is so small that to raise the bridges to a sufficient height to accommodate it would place an entirely unjustifiable tax and inconvenience upon the far greater business interest of the city concerned in crossing the river.
The following tables show the average number of days per annum during which various types of existing vessels would be prevented from navigation by bridges of various assumed heights above the Davis Island Pool:
| Assumed bridge height above pool level in feet | Present 6th St. bridge 33 | 37 | 42 | 47 | Present 6th St. bridge 33 | 37 | 42 | 47 |
|---|---|---|---|---|---|---|---|---|
| Types of Vessels | Total number of days per annum when clearance would be insufficient. | Total number of days per annum when clearance would be insufficient excluding days when river is above 15-foot stage. | ||||||
| Harbor tugs, average height 24´ | 12 | 3 | 1 | 1 | 3 | 0 | 0 | 0 |
| Harbor tugs, maximum height 27´ | 36 | 9 | 1 | 1 | 28 | 0 | 0 | 0 |
| Monongahela boats, ordinary maximum height 28´ | 57 | 12 | 2 | 1 | 48 | 3 | 0 | 0 |
| Monongahela boats, extreme maximum height 32´ | 198 | 57 | 9 | 1 | 189 | 48 | 0 | 0 |
In drawing conclusions from the above table, as a basis for plans governing the expenditure of millions of dollars in construction and the permanent establishment of conditions of navigation and of traffic over the bridges and the enormous business interests concerned, it is important to bear in mind that the types of vessels here considered are antiquated, and can undoubtedly be materially changed in many particulars to the benefit of all interests.
As bearing directly on this question of boats and bridges, attention is invited to the following extract from the report of Hon. D. S. Alexander, chairman of the River and Harbor Committee of the United States House of Representatives, in submitting for action of the House the last River and Harbor bill on February 11th, 1910:
Modern Type of Boats for Non-tidal Rivers.—"The British Government has been designing shallow-draft boats for use on the Nile, and the German and Austrian governments have been working along similar lines with reference to methods of transportation on the Rhine, the Danube, the Elbe and other waterways. The boats designed have been very successful, having been used in connection with modern loading and unloading appliances. On our western rivers little change has been made in the design of towboats, barges, etc., since 1860, and it is believed that a design embodying the best points of modern vessels, with modern machinery and cargo handling devices, might lead to a marked increase in the traffic on the non-tidal rivers of the United States, especially after permanently improved channels are available.
"It is believed that the appropriation of $500,000 to be expended in the purchase of plant for use in connection with the work of improvement of the river will also provide for experiments to be carried on by the Government which will result in improving the present type of river freight carriers; and also that these tests can be made in no other way, since the expenditures and uncertainties involved preclude the use of private capital for the purpose. As a result of the tests or experiments it is hoped that a large saving to the country at large may accrue from decreased costs of transportation, and that a type of carrier may be developed which will also reduce the cost of all bridges across navigable streams due to lessened requirements in the matter of head room."
This report of Colonel Alexander, the very able Chairman of the River and Harbor Committee of the House of Representatives, is worthy of serious consideration. Such an investigation and experiments to determine the best type of carriers to use on the river seems certain to be provided for and may result in clearly demonstrating that no necessity exists for raising the Allegheny bridges at all, in accordance with the possibility outlined by the closing paragraph of Colonel Alexander's report above. The appropriation of $500,000 as recommended by Colonel Alexander is included in the River and Harbor bill which has passed the House of Representatives and Senate. There is every probability that it will become a law.
A vast amount of water traffic is carried on inland waterways all over the world under fixed bridges with far less head room than is provided for under the Allegheny River bridges. It is customary in other parts of the country and the world to establish for rivers a minimum head room for bridges at a high navigable stage, which stage is considerably lower than the maximum or even the ordinary high flood stage. For instance, in the new barge canal being built by the State of New York at a cost of $108,000,000 the minimum head room under all stationary bridges is fixed at 15½ feet at the high navigable stage of the water. The high navigable stage is based chiefly upon what is a safe navigable stage, taking everything into consideration. It is by no means a very high stage. As this canal runs through the canalized Mohawk, Oneida, Oswego, Seneca and Clyde rivers, the situation is comparable with that on the Allegheny. The depth of the canal at low water is to be 12 feet, so it is seen that the clear head room is but about 25 per cent greater than the minimum depth of the water. The boats must be made to fit the bridges, and not the bridges to fit the boats. It is estimated that the amount of traffic which will pass through these canals about 450 miles long and under these 15½-foot bridges will be about 20,000,000 tons annually, many times the amount making use of the Allegheny River. The present Erie, Champlain and Oswego canals in the State of New York, which have been in operation for about 80 years, are crossed by several hundred bridges giving a clear head room of 13 feet. No complaint about this head room is known to exist, notwithstanding that steam vessels are largely used for navigation purposes on the canals. The boats have to be made to fit the bridges and not the bridges to fit the boats.
At Paris, the river Seine running through the city carries a very large amount of business. Annually about 20,000,000 passengers, and about 11,000,000 tons of freight are carried on boats of various kinds. There are 36 bridges which span the river and must be passed by the water-borne traffic. The clear head room under these bridges at the highest navigable water varies from 11.25 feet to 21.88 feet. By highest navigable water is meant the stage of water when by reason of floods or currents, navigation ceases. This Paris water-borne freight traffic on the Seine amounts to fully 7 times that of the Allegheny River and passes under 5 times as many bridges, with minimum available head room at high navigable stages just about one half that under the present bridges over the Allegheny at a 15-foot stage. The conditions of navigation on the Seine at Paris are practically the same as those on the Allegheny at Pittsburgh. In Paris the boats are made to fit the bridges and not the bridges to fit the boats.