If it were decided that a bridge having a total width of roadways of forty-four (44) feet and two eleven-foot sidewalks inside the trusses, would suffice for possible future conditions of traffic, the amount of money required for the combination would reduce to about $33,500,000.

It must not be forgotten that these totals do not include any allowance for right-of-way, property damages, equipment, or administration.

In conclusion the author offers the suggestion that, in view of the facts presented in this memoir, it might be advisable to give the economics of the proposed crossing of the North River some further study before finally committing the community to the policy that is now contemplated.

The preceding paper was delivered to the American Society of Civil Engineers in May, 1920, was accepted by the Publication Committee, and was printed immediately, advance copies of it being distributed for discussion. It was slated for delivery at the meeting of September third; but, upon very short notice, its reading was indefinitely postponed. The author hopes that, in the interests of engineering economics, this injunction against a thorough discussion of an important engineering problem of great magnitude will not prove to be permanent.

For about thirty years there has been discussed in the public press the proposed construction of an immense bridge across the North River to carry all kinds of traffic, including steam-railway trains; and to-day there is serious talk of materializing the project by building for that purpose a structure to cost two hundred millions of dollars. In the author's opinion, the construction of a high bridge over the Hudson at New York City for the purpose of transferring freight and passenger trains would involve a serious economic blunder from the engineering standpoint. His reasons for this rather drastic and sweeping statement are as follows:

First. It would cost more to build at this location a standard railway bridge carrying n tracks than it would to construct n single-track tunnels.

Second. The right-of-way and property damages would be much greater for a railway bridge than for the corresponding tunnels.

Third. The cost of operation to cover rise and fall is twice as great for the bridge as for the tunnels.

While the unnecessary expenditure of a large sum of money for the construction of the proposed bridge might be pardoned, it would be exceedingly uneconomic to saddle for centuries to come upon posterity a financial burden that will involve needlessly lifting and lowering ninety feet a load of two tons for each ton of freight carried across the river.