Historic Pelham: Construction of the Concrete Arch Pelham Bridge

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For much of the last two hundred years, there has been a bridge over the Hutchinson River where it empties into Eastchester Bay. The various bridges that have been built there have played a critical role in the development, and thus the history, of the Town of Pelham.

On March 6, 1812, the New York State Legislature enacted a statute incorporating the "Eastchester Bridge Company" to build a bridge over the Hutchinson River where it empties into Eastchester Bay. The bridge was built shortly afterward and is believed to have been completed by about 1815. In 1817, the Westchester and Pelham Turnpike Company was incorporated to construct a turnpike from the causeway at Westchester to the bridge. That bridge came to be known as "Pelham Bridge" -- the name it bears today.

Even in its first iteration, Pelham Bridge included a draw to permit ships to pass. Within its first few years, the first Pelham Bridge was destroyed by a storm. On April 12, 1816, the company was authorized by the Legislature to sell its property and toll franchise for a period of forty-five years. The second bridge was built in 1834 by George Rapelje, with the right to charge tolls for a period of thirty years, but the supervisors of Westchester County purchased the bridge in 1860 and made it free.

The bridge was replaced with an iron bridge constructed in 1869-1870. That bridge, in turn, was replaced by the present larger bridge, opened by the New York City Department of Bridges on October 15, 1908.

Today's Historic Pelham Blog posting transcribes a wonderful article published in May, 1910 detailing the construction of Pelham Bridge and includes a series of images published with the article. The most interesting of those images is the last one that shows foundations for the present bridge being laid next to the old iron bridge built in 1869-1870. The old bridge is clearly visible in the background.

I have written before about the history of the Pelham Bridge. For a lengthy list of such postings with links, see the end of today's article.

Below is the transcription of the article published in May, 1910, followed by a citation to its source.

"Concrete Arch Bridge at Pelham Bay Park

During the last few years concrete has almost entirely replaced stone masonry in the construction of highway bridges and has been employed largely in the building of those that no long ago would have been built of steel. For crossings demanding long spans, structural considerations have led to the use of the reinforced concrete arch. In many short, single span structures the same form has often been adopted because of its pleasing appearance.

The Pelham bridge is a structure of the first named class but one in which what may be termed the architectural features, in contradistinction to those of a strictly engineering nature, have received unusual attention. It is notable because of its magnitude, the small rise of the arch spans, their slenderness, and the peculiarly graceful appearance secured by the combination of these structural features with a not too elaborate ornamentation.

The bridge carries the Eastern boulevard, a continuation of the Bronx and Pelham parkway, across East Chester bay in Pelham Bay park, The Bronx, New York. With the two approaches the structure has a total length of about 1,770 feet and is 52 feet wide, the roadway taking 34 feet and each sidewalk 7 feet of the width. In its design the result aimed at was to provide not only a strong and permanent structure, but also one that would harmonize with the system of parkways of which it forms a part.

The bridge proper consists of six elliptical reinforced concrete arches of the Melan type, each having a clear span of 105 feet. They are divided into two series of three spans each by a Scherzer lift span, which forms the central feature of the structure. This is of the double leaf type, and when open will give a clear waterway of 60 feet.

The original plans provide for four ornamental towers which will be erected over the arch abutments next to the lift span, and will flank the same, emphasizing the gateway to vessels. These towers have not been built, but detail plans are being prepared at the present time, and it is understood that the contract for the towers will be let in the near future, and until they are built the bridge will not represent all that its designers intended.

The bridge was built under two contracts, one for the substructure and one for the superstructure. The former was awarded to W. J. Lawler for $208,905 and the latter to the Godwin Construction Co. for $257,375.

All piers and abutments are founded either directly on rock or on piles driven to rock. The profile of the bottom at the bridge site indicated a depth of water varying from 6 to 29 feet. While the 38 washborings which had been made under the supervision of the assistant engineer of the department of bridges, J. G. Theban, to ascertain the nature of the foundation soil, showed strata of sand and gravel overlying the rock to a maximum depth of 30 feet, the greatest depth to bed rock to which any foundations had to be carried was 52 feet below mean high tide. This depth existed for both center abutments. After considerable investigation it was determined that the least expensive foundation at this location would be to carry the masonry down to an elevation 37 feet below mean high tide, supporting the same on piles driven to rock and cut off at an elevation approximately 35 feet below mean high tide. All piles were driven vertical by the use of a pile driver with extension leads and an ingenious device invented by the contractor to make possible the use of short piles although they had to be driven from 25 to 30 ft. of water. This device consisted of a tube slightly larger in diameter than the size of the pile, which was kept suspended between the leads of the pile driver, the upper edge of the tube being slightly above the water. A pile 20 or 25 ft. long would be picked up by the pile driver and dropped into the tube. A maple wood follower was then entered after the pile and the pile driven home. Piles were driven quite rapidly, frequently at the rate of one in seven minutes. After all piles were driven they were cut off at the proper elevation, open cofferdams were built and the concrete placed therein by means of closed buckets which were lowered into the water and opened automatically when reaching the bottom.

On account of the extreme flatness of the arches, which exert a horizontal thrust of about 100,000 lbs. per lin. ft. on the abutment 60 ft. above the base of the foundations, special arrangements had to be made to prevent overturning or a sideways motion of the abutments due to the horizontal thrust. It was not practicable to drive inclined or batter piles, as is most frequently done to serve this purpose and which were used under the end abutments, on account of the great depth. The method used was that the two center abutments were designed with heavy concrete [text continued below image]

PELHAM BRIDGE, PELHAM BAY PARK, THE BRONX,

NEW YORK CITY -- UNDER CONSTRUCTION.

[Page 190 / Page 191]

Left: "END OF ARCH AND ABUTMENT--PELHAM BRIDGE."

Right: "PIER OF PELHAM BRIDGE--ARCH CENTERS STRUCK."

toes projecting 19 ft. into the channel, these toes being connected by three concrete struts, 7 ft. high and 15 ft. wide, reaching clear across the channel, and being located below the depth required by the U.S. government for clearance in the channel. These toes and struts were heavily reinforced with bars, 1 3/4 in. Thacher bars, old style, being used, spaced as close as 6 ins. c. to c. About 60 tons of such bars were placed with the help of divers at a depth of 35 ft. below mean high tide and later on embedded in concrete.

Before undertaking this part of the work, practical tests were made by Mr. Theban to determine whether it would be possible to locate reinforcing bars in deep water and embed them in concrete, under similar conditions to those proposed in the foundation plans for the bridge. These tests, proved to be very successful, and the work on the bridge was then executed as described.

The arches have a rise of 16 ft. 6 ins. and a thickness at the crown of 2 ft. Each arch is reinforced with 18 Melan ribs spaced at equal distance apart and made up of 3 x 3 x 3/8 in. angles latticed together. The ribs were made in four sections spliced together at the crown, at two intermediate points and at the haunches with the corresponding ribs in adjacent arches. At each splice location transverse cross bracing was used to bind the ribs together.

Generally speaking, details of design and specifications for the superstructure did not vary much from those ordinarily used in Melan bridges of similar magnitude, and which are more or less familiar.

Objections are frequently made against the surface appearance of concrete bridges, due to unsatisfactory workmanship or lack of knowledge of how to avoid ragged edges, hair cracks, efflorescence etc., and it was therefore decided that all concrete surfaces exposed to view should be tooled. The grey cement color being also objectionable a layer of what might be called brick concrete was used for all outside surfaces, dark red brick chips taking the place of a stone aggregate. The result was very satisfactory.

The preliminary general studies for the Pelham bridge were first made by the department of parks, and afterwards [text continued below image]

"FOUNDATIONS FOR PELHAM BRIDGE--

OLD STRUCTURE IN BACKGROUND."

[Page 191 / Page 192]

by the department of bridges of New York City, while Gustave Lindenthal was commissioner. The Concrete-Steel Engineering Co., of New York, the owners of the Melan patents, were retained to design the structure and to act as consulting engineers during the execution of the work. Henry F. Hornbostel, architect to the bridge department, collaborated with the engineers as far as the architectural details were concerned. J. G. Theban, assistant engineer of the department of bridges, was directly in charge of the structure from the outset.

The accompanying views illustrate quite clearly some of the main features of the Pelham bridge, and the view of the old bridge which is also given shows better than any mere description the great changes in, and the important development of highway bridge construction within the last fifty years."

Source: Concrete Arch Bridge at Pelham Bay Park, Good Roads, May 1910, pp. 190-92 (NY, NY: E.L. Powers Co. 1910) (images above part of the article as well).

* * * * *

The last image above clearly shows the old iron bridge built in 1869-1870 in the background. There is another well-known view of the same old iron bridge that was published in 1884 in Harper's Weekly as part of a page of images showing various parts of Pelham Bay Park