THE NEW

OMAHA BRIDGE.-

3

THE NEW OMAHA BRIDGE.

I.

PRELIMINARY NARRATIVE.

The original Omaha Bridge was begun in 1869, and opened fortraffic in 1872. It was built under the directions of Mr. TheophilusE. Sickels, Chief Engineer. The contract for the entire work wasoriginally let to Mr. L. B. Boomer, of Chicago , but by a subsequentarrangement the foundation work was done under the immediate chargeof the Chief Engineer.

As originally built this bridge consisted of eleven spans, of 250 feeteach; the approach on the east side being a solid embankment, andthat on the west side a cottonwood trestle which was shortly afterwardsfilled. In 1877 the two easterly spans were blown down; and theeastern span was never restored, its place being supplied by an inexpen-sive timber trestle. The substructure consisted of eleven iron piers andone stone pier, all of which were founded on rock, the iron piers beingnumbered from west to east. The eastern iron pier and the stone pierat the west end were buried in the embankments of the approaches.Each pier consisted of two cylinders 8^ feet in diameter, placed 18^feet between centers, and braced together by cast-iron struts and diagonalties above low water. The cylinders of Pier XI. (buried in the bank)were of cast iron for the whole height of the pier. The cylinders ofthe other piers were of cast iron below high water, the sections being10 feet long, cast in a single piece and bolted together through internalflanges. Above high water the cylinders were of wrought iron, ofan inch thick, with heavy cast-iron caps. The lower 12 feet of thecylinders were filled with concrete, which appears to have been tightenough to exclude the water; above this the cylinders were filled withrubble masonry. The cylinders were more or less irregular in position;

and in providing for the erection of the superstructure of the newbridge it became necessary to figure very closely to overcome theseirregularities.

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The original superstructure was for a single track, ‘ of the Postpattern, the trusses being 28 feet deep, divided into twenty-two panels,the web being of the triple-intersection system. The trusses werespaced 18^ feet between centers. The top chords were of cast iron, andall other principal members of wrought iron. The new span whichreplaced one of the spans blown down in 1877 was of wrought ironthroughout, of the same depth and width as the other spans, but of thedouble-system Whipple type, with vertical end posts. The bridge wasthe most prominent example in America of the Post superstructureand pneumatic cylinder piers.

At the time this bridge was built the regimen of the river in frontof Omaha was very uncertain, the tendency being for the channel tomove eastward rather than westward. Subsequently a cut-off above thecity gave the river a more stable character, and the channel moved tothe west. Had the construction of the bridge been deferred ten yearsthe channel would have skirted the bluff on which Omaha is built, theentire bottom-land now occupied by railroad yards and other interestsin front of the city would probably have been washed away, and thesituation would have become an exceptionally favorable one for theconstruction of a bridge.

In May, 1885, at your request I visited Omaha and made a carefulexamination of the old Omaha Bridge . As the result of this examina-tion, on May 23 I made a full report to you, in which I consideredcertain modifications which it seemed important should be made at allevents, and recommended a plan for the reconstruction of the entirebridge as a first-class double-track railroad bridge with independentroadways for travel.

On the 10th of September, 1885, you telegraphed me to takemeasures for rebuilding the bridge on the plan recommended in myreport. On September 18, 1885, you wrote to me that at a meetingof the Executive Committee it was voted to proceed at once with thework of reconstruction, and you instructed me to proceed to reconstructthe Omaha Bridge in the manner recommended in my report of May 23.

On September 19 I appointed Mr. H. W. Parkhurst AssistantEngineer of Foundations, and directed him to proceed at once to Omaha and take charge of the work. Mr. Parkhurst arrived at Omaha on

September 22, and made arrangements for beginning the foundationwork immediately. The construction of the new Omaha Bridge reallydates from this day.

The fact that the work was the reconstruction of an old bridge,over which a heavy train service was to be maintained at all times,made it seem expedient to keep the control of the work as much inthe company’s own hands as possible. It was therefore determined todo everything on the ground by day’s work under the immediate direc-tion of the engineers, except the building of the masonry, which it wasthought best to do by contract. The foundations were put in by thecompany’s own men by day’s work, and the superstructure was erectedin the same manner, the material being manufactured at an Easternestablishment by contract.

On October 13 a contract was closed with Messrs. T. Saulpaugh& Company, for the construction of the masonry.

On the evening of December 11 Mr. Parkhurst met with a seriousaccident in Omaha near his residence, which incapacitated him fromwork for several months. On December 15 Mr. George A. Lederle tookMr. Parkhurst’s place, and as Resident Engineer continued in imme-diate charge of the work until the bridge was completed.

The framing of the timber for the caisson for the first pier wasbegun October 29, and air pressure was put on December 15, the daythat Mr. Lederle took charge of the work.

On December 7 invitations were sent to nine prominent bridgebuilders, inviting proposals for the construction of the superstructure;eight of these parties responded. The proposals were opened on De-cember 29, and the work was awarded to the Union Bridge Company,as the lowest bidder.

The work was continued without interruption from this time for-ward, the erection of the last span being finished May 14, 1887.

After the first of June, 1887, the difficult part of the work beingentirely completed, Mr. Lederle was transferred from Omaha to Portland ,Oregon , where he took charge of the bridge across the WillametteRiver; and Mr. E. Duryea, Jr., was appointed Resident Engineer. Thebridge was completed before the connecting tracks were ready on eitherend, and it was not put in use as a double-track structure until October 1,1887.

On the 10th of November, 1887, Mr. Duryea and others droveacross and returned in a carriage, thus using the carriage-ways for the