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Historic American Engineering Record
Sewickley Bridge
(Bridge #1 Ohio River)
HAER No. PA-53

Spanning the Ohio River in the vicinity of Sewickley Borough
Allegheny County

National Park Service
1849 C Street, NW
Washington, DC 20240

PA-53 Sewickley Bridge
Master Photo List

Spanning the Ohio River in the vicinity of Sewickley Borough in Allegheny County, Pennsylvania.

Photos taken by Ron Lowe, July 1979.

HAER PA-53-1 - - - East elevation oblique, looking south.
PA-53-2 - - - Elevation view looking downstream.
PA-53-3 - - - Elevation view looking upstream.
PA-53-4 - - - Elevation view, south approach looking west.
PA-53-5 - - - Elevation view, north approach looking west.
PA-53-6 - - - Main span portal, looking north.
PA-53-7 - - - Main span framing, looking north.
PA-53-8 - - - Main span tower framing at pier 3.
PA-53-9 - - - Main span top chord bracing of pier 2.
PA-53-10 - - - Pinnacle at top of pier 3 tower, west truss.
PA-53-11 - - - Elevation view, north abutment.
PA-53-12 - - - North approach spans.
PA-53-13 - - - Anchor bearing at west end of pier 4.
PA-53-14 - - - West end elevation of pier 4.
PA-53-15 - - - North elevation of main river pier 3.
PA-53-16 - - - Main truss interior bearings at pier 3.
PA-53-17 - - - Sidewalk support bracket and handrail, east side, looking north.
PA-53-18 - - - Handrail at west side.

HAER No. PA-53
Index to Photographs
(page 2)

PA-53-19 - - - Apron plant and open curb.
PA-53-20 - - - Main-span floorbeam end connection repair.
PA-53-21 - - - Pony truss, bottom chord repair.
PA-53-22 - - - Eyebar repair at panel point 24, west truss.
PA-53-23 - - - West elevation oblique, looking north.
PA-53-24 - - - East elevation oblique, looking north.
PA-53-25 - - - Index of record photographs, keyed to elevation drawing of bridge.
PA-53-26 - - - Measured drawing, February 197B, Title sheet.
PA-53-27 - - - Measured drawing, February 1978, Plan and elevation.
PA-53-28 - - - Measured drawing, February 1978, Typical cross sections.
PA-53-29 - - - Measured drawing, February 1978, Substructure details.
PA-53-30 - - - Measured drawing, February 1978, Location plan (original drawing).
PA-53-31 - - - Measured drawing, February 1978, End anchorage details (main trusses).
PA-53-32 - - - Measured drawing, February 1978, Structure details.
PA-53-33 - - - Photocopy, original design geometry of the structure.
PA-53-34 - - - Photocopy, stress sheet of anchor and cantilever arms.
PA-53-35 - - - Photocopy, stress sheet of suspended span.
PA-53-36 - - - Photocopy, details of upper chord member U6 - U7.
PA-53-37 - - - Photocopy, details of bottom chord member L6 ~ L8
PA-53-38 - - - Photocopy, details of bottom chord member L4 - L6.
PA-53-39 - - - Photocopy, details of wind bracing on bottom chords.
PA-53-40 - - - Photocopy, wing traveler.
PA-53-41 - - - Photocopy, creeper traveler at U20 (at top) and creeper traveler in advance of P.P. 21 (at bottom).
PA-53-42 - - - Photocopy, Sewickley Bridge and surroundings, 1911.

Bridge #1 Ohio River (Sewickley Bridge)
(HAER PA-53)

Location: Spanning the Ohio River in the vicinity of Sewickley Borough in Allegheny County.

Date of Construction: 1909-1911 for Allegheny County, Rehabilitated 1948.
Emergency Repairs 1974, 1977.

Present Owner: Commonwealth of Pennsylvania
Pennsylvania Department of Transportation.
Harrisburg, Pennsylvania

Present Use: The Bridge is a two lane highway and pedestrian structure. At the present time the structure has a posted vehicular load restriction of 3 tons and a speed restriction of 10 miles per hour. Both sidewalks are closed to pedestrians.

Significance: The Bridge is representative of the type of bridge that was being built at the turn of the century. Also significant, because of the attention it has had since its inception and resultant completion, and because of the direct relationship the bridge holds in the development of and communication between the surrounding communities of Sewickley and Coraopolis.

Historian: Pennsylvania Department of Transportation, February 1978.

"It is understood that access to this material rests on the condition that should any of it be used in any firm or by any means, the author or draftsman of such material and the Historic American Engineering Record of the National Park Service at all times be given proper credit".

HAER No. PA-53
(Page 2)



Geography of Site...4
First Conception of a Bridge...5
Rebirth of Interest...8
Consummation and Approval...11

Foundation Construction...17
Superstructure Fabrication and Construction...19
Engineering and Technological Significance...32

Maintenance and Repairs...36
Changes in Surroundings...40
Physical Condition of Structure...43
Cultural, Social and Economic Significance...51
Structure Replacement...54


A. Similar Structures...64
B. Inspection Report Photographs...71
C. Maintenance and Repair Record...78
D. Chronology...81


(Page 3)


In December, 1977 the Pennsylvania Department of Transportation was authorized to prepare an historical documentation of the Sewickley Bridge for the review of the Historic American Engineering Record. The assembled information comes primarily from community and engineering publications, original contract and construction drawings, subsequent engineering inspection reports, county and state records, personal interviews and economic studies by local educational institutions.

The purpose of the documentation is to explain and record the geographic background, need for and significance of the bridge as it relates to the early and subsequent history of the area and to record the design and construction of an early engineering achievement.

(Page 4)


Geography of Site

The structure is commonly known as the Sewickley Bridge because of its almost direct attachment at the north end to the Borough of Sewickley and because of the positive relationship the bridge has had in the development of that community.

Sewickley is located on the north shore or right bank of the Ohio River approximately 12 miles downstream from the City of Pittsburgh. Early historical accounts depict the town as a general stopping point for travelers moving by riverboat or overland to and from the City of Pittsburgh (1) History records the official formation of the community as a town in the early autumn of 1840 with the adoption of the name "Sewickleyville."(2) Thirteen years later the village was incorporated as the Borough of Sewickley. Because of its picturesque location the area grew in popularity through the years and developed into an attractive residential community.(3)

HAER No. PA-53
(Page 5)

The south end of the Sewickley Bridge lies within the boundaries of the area presently known as Moon Township. The Borough of Coraopolis, also located on the south side is approximately 1 mile up river from the bridge site. In the early 1800's this area was well known for its fine farms.

First Conception of a Bridge

The initial move to erect a bridge at Sewickley dates back to 24 November 1894 when a meeting was held in the local residence of Gilbert Hayes. The meeting call read as follows:

"To consider the erection of a free bridge over the Ohio River, from the line between the Borough of Osborne and Sewickley to a point in the township road in Moon Township.(4)

Historical accounts indicate that the meeting was well attended and the principal address was made by the Honorable Judge Morrison Foster, a brother of Stephen C. Foster (5) and resident of the adjacent community

HAER No. PA-53
(Page 6)

of Edgeworth. The Judge spoke at length on the great need of the adjoining communities for a new river bridge. He pointed out that there was no wagon bridge over the Ohio between Pittsburgh and Wheeling for a distance of 100 miles; that the existing ferry services on the river were unreliable and often abandoned for days during the winter months; that many farmers on the heights north of the town were adverse to coming to Sewickley because of the steep grades to and from the town and river; and that the Ohio River practically divided the county without means of communication. These adversities naturally resulted in financial losses and depreciation of property on both sides of the river. The Judge also noted that the County Commissioners had the power to erect a bridge by an act passed by the General Assembly in 1891.

As a result of this meeting, a committee of 15 members was formed to prepare a formal petition to be presented to the County Court calling for the building of a new bridge.(6)

(Page 7)

Later in the following year, 1895, the committee petitioned Judge J. W. F. White, a Sewickley resident who was Judge of the Common Pleas Court No. 2, for a ruling on the construction of a new bridge. The site proposed for the bridge was from the foot of Chestnut Street, Sewickley to Lashell's Ferry in Moon Township. An initial inspection of the site was made by the Court appointed board of viewers, followed by subsequent meetings and reinspections.

The final report the viewers made to the court was adverse to the building of the bridge. The County officials readily accepted the report and disapproved the entire bridge project. The officials argued that they were not convinced of the need for the bridge and that the cost estimate of $400,000 would mean a one mill levy on all County taxpayers for a project that would serve only a few. They also expressed concern that a new County-built bridge in Sewickley would set an undesirable precedent as other communities in the County might petition for similar county bridges and require further increases in tax millage.(7)

(Page 8)

It is interesting to note that in 1897 the Rochester-Monaca vehicle bridge over the Ohio River was opened, breaking the long unbridged stretch of the Ohio River between Pittsburgh and Wheeling.

Rebirth of Interest

A renewed interest in a bridge culminated in November, 1906, when residents of the area petitioned for a new bridge to the Court of Quarter Sessions of Allegheny County. Several of the prime movers in the first petition were also foremost in this revival.

The court records show that generally the same facts argued in the preceding petition were set forth as follows:

1. The absence of bridges over the Ohio River for a distance of approximately 12 miles upstream and downstream from the proposed site;

HAER No. PA-53
(Page 9)

2. The difficulty, delay, danger and frequent impossibility of crossing;

3. The effect of such interference with travel and intercourse upon the development of the county; and

4. The extent and importance of this section of the county divided by the Ohio River.(8)

It is interesting to note that the petition included a drawing of the proposed structure and surrounding topography. The proposed location for the bridge was generally where it stands today. However, the type of main span shown was that of a suspension bridge.(9)

In reviewing the petition, the court appointed a new Board of Viewers, one of whom was Charles Davis, then County Engineer. In early December, 1906, the viewers recommended to the court that a bridge should be constructed at the existing site, but since the cost would be greater than it was reasonable for Sewickley Borough and Moon Township to bear, they recommended that the County bear the total cost.

HAER No. PA-53
(Page 10)

The Court accepted the Viewers' recommendations on 6 December 1906 and on 17 December 1906, the Grand Jury gave their approval. These approvals finally provided the County Commissioners with the authority to construct the bridge. However, approval for actual construction did not come immediately. The County Court records show that a number of counter petitions were filed by Mr. W. H. S. McKelvey who owned property at the Sewickley end just to the west of the proposed structure. These suits delayed actual construction work by approximately two years.

Preliminary surveys were made during the spring and summer of 1906 to fix accurately the length of the spans and locate the piers and abutments.

The approval of the then Secretary of War, the Honorable William F. Taft, was next required. On 28 June 1907, the Secretary appointed a Board of three Government Engineers to view the site and examine the plans for the proposed bridge. On 6 February 1908, the Secretary issued the building permit and on 10 April 1908, the County Commissioners filed their concurrence with the

HAER No. PA-53
(Page 11)

Court of Quarter Sessions and appropriated funds for construction in the following year.

Some important facts that appeared to have strongly influenced the County Commissioners in assuming the expense of the bridge were that there was no highway bridge over the river above Rochester which is 25 miles below Pittsburgh; Sewickley is approximately midway between Rochester and the Point in Pittsburgh; Sewickley and Coraopolis are the largest towns on the Ohio River in Allegheny County; and also the bridge would be a connecting link between the most admirably improved road systems on either side of the river.(10)

Consummation and Approval

The contracts for the construction of the bridge were awarded on 2 July 1909 to the Adam Laidlaw Company for $98,907.25 for the masonry, and to Fort Pitt Bridge Works for $372,400.00 for the superstructure. The time limit set for completion was 30 November 1910.(11)

HAER No. PA-53
(Page 12)

The County Engineer in charge of the design was Mr. J. G. Chalfant, while Mr. V. R. Covell was his Deputy, and Mr. A. A. Anderson was his assistant. Mr. Charles Davis, who preceded Mr. Chalfant, was in charge of preliminary designs but died on 21 February 1907.(12)

The Sewickley Bridge is a 9-span steel truss structure with a total length of 1,852 feet, 7 inches and a lateral width of 32 feet between centerlines of trusses.

The approach spans at each end of the bridge consist of 3 simple span Warren-type pony through trusses (Dimensioned Drawing 2, Page 120)

The main river bridge over the river channel is a 3-span cantilever through truss structure with 300-foot long end anchor spans and a 750-foot long center span. In the center span a 350-foot long simple span is suspended between the free ends of the 200-foot long trusses cantilevered out from each main river pier (Dimensioned Drawing 2, Page 120).

HAER No. PA-53
(Page 13)

The original details were designed for a 23-foot vehicular roadway with two streetcar tracks astraddle the centerline and 6-foot pedestrian sidewalks on brackets outside of the trusses (Dimensioned Drawing 3, Page 121).

Originally the structure passed over railroad tracks only at its south end and connected a 2-lane asphalt road at the south end to the paved street system at the north or Sewickley end (Dimensioned Drawing 5, Page 123).

A Jubilee Celebration inaugurating the first step in the construction on the bridge was held in Sewickley on 21 July 1909, with Burgess W. K. Brown of Sewickley, and Burgess A. D. Guy of Coraopolis breaking ground for the approaches.(13)

The structure was officially opened to traffic on 19 September 1911.

HAER No. PA-53
(Page 14)



Final surveys, designs and contract plans were prepared by Allegheny County under the direction of Mr. J. G. Chalfant, County Engineer. The contract plans consisted of 27 drawings showing loadings, member makeups, general details and arrangements of all parts of the substructure and superstructure. Of these original drawings, only Sheet 1 of 27, showing soundings, topography and location for the bridge, has been located (Dimensioned Drawing 5, Page 123).

Records indicate that the dimensions and elevations of the structure as shown on the County design drawings were rigidly followed (Figure 1, Page 63). The length of the channel span, alignment of the bridge with relation to river current, and the clearances above water were fixed to the regulations prescribed at that time by the Federal War Department.

HAER No. PA-53
(Page 15)

The geometric outline and many of the general details of the main span trusses were similar to those of the then existing Wabash Railroad Bridge at Pittsburgh.(14) However, at Sewickley the floor system details were designed for highway rather than railroad loadings.

The initial floor system consisted of a 4-inch thick wood block pavement on a 1-1/2 inch sand bed above a concrete filler slab, averaging about 3 inches thick, and supported by a 3/8-inch thick steel buckle plate turned down, over steel stringers and floorbeams. The sidewalks were reinforced concrete slabs with an average thickness of 5 inches supported by two lines of steel stringers.(15)

The substructure consisted of two abutments with wingwalls, four pairs of pedestals, two on each end, supporting the approach spans, two anchor piers and two main channel piers. All piers were sandstone faced and backed with gravel concrete. Granite bridge seats were provided under the main span tower bearings at Piers 2 and 3 (Dimensioned Drawing 4, Page 122 ).

HAER No. PA-53
(Page 16)

The structure was designed for dead, live and wind loadings. The dead load included all superstructure components and details, including streetcar rails.

Separate live load assumptions were applied in the designing of the floor system and trusses. Floor system members were designed using either a uniform load of 100 pounds per square foot of clear roadway and sidewalk, a 15-ton road roller, a wagon load of 5-ton or two 50-ton streetcars in tandem. For the trusses, a live load of 1,600 pounds per lineal foot of truss was used for designing the main span and 2,000 pounds per lineal foot of truss was used for designing the approach span truss members.

A wind load of 35 pounds per square foot was applied to the exposed vertical surfaces of both trusses of the unloaded structure. This wind load was applied to both the main and approach trusses.(16)

There is no record of the actual type of steel used on the bridge but recorded allowable working stress

HAER No. PA-53
(Page 17)

information indicates that a structural carbon steel was used for all parts of the bridge including the forged eyebars (17) Also, results of tests taken of sample specimens removed from the structure during subsequent in-depth inspections confirm this assumption.(18)

Foundation Construction

As previously noted (Page 8 above) preliminary surveys made in 1906 were sufficient to fix accurately the length of the spans and locate the piers and abutments, from which final designs were made and grades established for the bridge and its approaches. The records indicate that in June of 1909 the centerline was monumented on both sides of the river and a triangulation system was developed for construction. It is also recorded that this survey was completed to a very high degree of skill and accuracy.(19)

It is important to note that some subsurface investigations were conducted prior to the foundation design and construction, although no original soils

(Page 18)

information is available. An account in a local periodical recorded the commencement of this phase of work as follows:

"The soundings are being made in the river at the foot of Chestnut Street with a drill boat that a good foundation may be found for the new bridge, which will be erected during the next year. The drill boat, before being put to use, sprung a leak and sank and had to be raised before soundings could be made."(20)

Piers 1, 2 and 3 are recorded as being founded on rock, approximately 30 to 35 feet below Elevation 684.4, the full pool elevation at that time. Cofferdams were used during the construction of these river piers and no unusual difficulties were encountered.

The northern anchor pier, No. L7, was founded on very dense clay and gravel at Elevation 706.4 about 20 feet above full pool elevation.(21) Pedestal and abutment footings appear to have been constructed in the dry and also rest on clay.

(Page 19)

The bearings and anchorage details used at Piers 1 and 4 are important features of the bridge design (Dimensioned Drawing 6, Page 124) since these assemblies are subjected to uplift under normal dead loading and most lane loading and are also located at the expansion points in the superstructure. An eccentric ring detail was included in the hold-downs to provide the vertical adjustment needed to insure proper contact in the top of the expansion linkages. The hinged eyebar details provided for additional longitudinal adjustments during construction. The heavy lattice girders that are embedded within Piers 1 and L1 to which the bottom eyebars are attached were a result of uplift calculations made by the contractor. His calculations showed the superimposed masonry weights of the piers to the anchorages as originally designed were not adequate to resist the maximum design uplift loadings.

Superstructure Fabrication and Construction

The Fort Pitt Bridge Works, the superstructure contractor, began work immediately after the contract was awarded. Since the contract included both fabrication

HAER No. PA-53
(Page 20)

and construction of the superstructure, it was necessary to review the design in detail and from a practical standpoint to determine how it could be best adapted to their methods of operation in the drawing room, fabricating plant and in the field.

They first proceeded with careful reviews and some revisions of the estimated weights and dead loads and then made graphical analyses of the stresses and reactions (Figures 2 and 3, Pages 64 and 65). At that time a special squad of their own engineers and draftsmen was assigned to devote full time and attention to this particular job under the supervision of Mr. A. W. Buel, a private consultant especially hired for this work, and afterward retained, during construction, as Consulting Engineer.(22)

From the results of the graphical check analyses and other considerations, it seemed that the weight of that part of the anchor piers directly over the anchorage might possibly not have a sufficient margin of safety, and, if the greater part of the mass of masonry above the elevation of the anchorage could

HAER No. PA-53
(Page 21)

be made absolutely effective, there would be a considerable excess. As some progress had already been made on one of the anchor piers, any change in the anchorage had to be decided on immediately or serious delay would result. It was suggested, therefore, that heavy lattice girders, extending nearly the entire length of the pier, should be embedded in the concrete so as to bring practically the entire weight of the superimposed masonry into positive action to resist the uplift. This suggestion was adopted, with the incidental advantage of reinforcing the piers so that no danger of cracks need be apprehended.(23)

Further studies and stress computations resulted in additional recommendations for changing the original design of some of the bridge members. It was also contemplated in the preliminary planning that it might become desirable or necessary to make the anchor span at each end work as a simple truss supported only on the piers before the cantilever arm was erected.

The end posts and top chords of the anchor arms, from L0 to U8, as originally designed, consisted of

(Page 22)

eyebars packed inside and outside of two 28-inch built-up channels, latticed top and bottom.(24) These members would not have been adequate in this simple truss to support the required loads. Consequently, these chord members were revised and made entirely of built-up riveted sections which would carry all anticipated loads in both tension and compression (Figure 4, Page 66). Also, to make the anchor arm work as a simple truss, it was necessary to add temporary members, U2-M3 and U4-M5, and to increase the section for M3-L4 and M5-L6.

These changes in the top chords, the additional web members and the loads for construction requirements made it advisable to alter the design for the bottom chord sections from L6-L14. These members were changed from two built-up channels (with four 6"x6" angles) to two built-up I-sections (with eight 6"x6" angles). This reduced the unsupported length of the top and bottom lattice bars so that flats could be used instead of channels or angles(25) (Figure 5, Page 67).

As the shop details were being developed, several features were incorporated to aid in simplifying the fabrication.

HAER No. PA-53
(Page 23)

An effort was made to standardize the rivet spacing as much as possible. On the upper chord, U6-U7, which is typical (Figure 4, Page 66) all lattice bars, top and bottom, were made in two lengths without any special bars. This result was obtained by varying the rivet pitch slightly to compensate for the difference in dimensions between gage lines and by varying the length of the end tie plates. This plan was followed throughout the work, an effort being made to keep the lattice bars of the same length for all similar members and thus to avoid special bars.(26)

Contract plans called for lower chords to have double lattice bars top and bottom made from light channels. This produced a bad detail where they crossed and the channels were difficult to connect. An effort to find a satisfactory substitute without increasing the weight resulted in the use of single angles flattened at the ends where they connected with the main member and at the center where they crossed each other (Figure 6, Page 68). Tests showed that when the ends were flattened out the center of gravity of the angles was in the plane of the under side of the flattened portion.(27)

HAER No. PA-53
(Page 24)

The tests also showed that the efficiency for the angles was from 30 percent to 50 percent greater than for the channels and the computations showed that it was due to the very small eccentricity of the angle connections.(28)

There was very little provision made for vertical adjustment of the structure during construction. The holes in the rocker links connecting the pin, L0, in the bottom chord with the pin in the upper end of the anchor bars were not bored until after the anchor bars were in place. Elevations were then carefully taken on the upper pin holes in the anchor bars and the rocker linkages were bored to such lengths as were required to locate the truss pin, L0, at the correct elevation.(29)

The trusses were shop assembled during fabrication and all pin holes bored as accurately as possible.

In this structure the buckle plates were designed to carry the loads normally carried by the bottom lateral bracing except at the hangers for the suspended span, where a shear lock is used to carry these loads from the suspended span to the cantilever arm.

(Page 25)

This shear transfer device, worked out in the fabricator's drafting room, was one of two similar devices which were said to have been unique at that period of time (Figure 7, Page 69).

As the construction plans and procedures were developed it was determined which bridge members must be redesigned or reinforced to carry the additional loads from the materials and equipment scheduled to be used and supported on the structure during construction.

Shelf angles with supporting stiffeners were designed to carry the stringer reaction due to the locomotive crane working from the bridge floor.

Other construction loads were provided for when the design of the anchor span was changed to make it work as a simple truss.

Construction started at the north end or on the Sewickley side of the river.

HAER No. PA-53
(Page 26)

The pony trusses for each simple half-through approach span were assembled on the ground and then hoisted into position with a 30-ton locomotive crane. The floor system was filled in between the trusses and the crane moved ahead on a track which was laid on the buckle plates and along the centerline of the bridge. As each span was completed, the crane moved ahead to repeat its previous operations on the subsequent span.

These approach spans could have been erected using various other types of equipment. However, the Contractor elected to use the 30-ton locomotive crane, which was located on the bridge floor, to erect the falsework and floor system for the anchor spans. Therefore, it was logical to use the same piece of equipment to erect the approach spans. After the third approach span was completed, the locomotive crane had only to be moved ahead to the anchor pier and it was in position to begin the falsework for the anchor span of the main structure.

HAER No. PA-53
(Page 27)

The construction procedure for the anchor span floor system was similar to the procedure used for the approach spans. The locomotive crane was used to assemble and erect the timber falsework bents and bracing for one panel ahead of the crane. Then the floor system, which included floorbeams, stringers and buckle plates, was erected, bolted together and blocked to elevation on the falsework.

The track was then extended and the locomotive crane was moved ahead and secured in position to construct the next panel of floor system and its supporting timber falsework.

This procedure was repeated, progressively, from the anchor pier to Panel Point 18.

The falsework bents were built wide enough to carry standard gauge tracks running parallel to and outside of each truss. Each track of two steel rails on timber ties was carried between bents by four, 24-inch deep steel I-beam stringers with two stringers under each rail.

HAER No. PA-53
(Page 28)

This track carried a traveling frame which was referred to as a gantry or wing traveler by the Contractor (Figure 8, Page 70).

The traveling frame served as a support for staging or platform for workmen, equipment, tools and materials. Rope falls or block and tackle were hung from the cross beams to lift the bridge members and set them in place.

This traveler was probably one of the first of this type that was made of steel. It was also made so it could easily be adapted for use in erecting other structures. Previously, "it was common practice to build a special timber traveler for each job.(30)

The cross beams were not high enough to clear the towers so it was necessary to build another braced frame on top and to the rear of the traveler so the upper most members of the tower and the higher top chord members of the trusses could be lifted into position. Timber booms (Chicago booms) were also installed

HAER No. PA-53
(Page 29)

on the top vertical members to facilitate the construction. To complete the tower, the traveler had to be moved to the channel side of the cantilever pier. Then the traveler was moved ahead to complete the cantilever arm to Panel Point 18.

"As each successive panel was erected by the gantry traveler, from Panel Point 10 to Panel Point 18, the wedges were backed out at all points outside of the cantilever pier" (31) which gradually transfered the weight of the entire span from the falsework to the anchor and cantilever piers.

With the gantry traveler at Panel Point 18, a second movable frame or "cantilever traveler" (32) as it was called, was erected on the top chords over Truss Panels 16-17 and 17-18.

The cantilever traveler moved on a track laid on the upper chords and was used to complete the construction of the suspended span to Panel Point 23, which is at the center of the structure (Figures 9 and 10, Page 71).

HAER No. PA-53
(Page 30)

With the suspended span erected to the center and with the cantilever traveler in its position nearest the center, the uplift at the anchor pier was maximum during construction and nearly equal to the maximum uplift for the finished bridge, with live load on the cantilever and suspended spans only. At this point the eccentric bushings in the shoes at the anchor pier were adjusted (Dimensioned Drawing 6, Page 124).(33)

The bushings were rotated to bring the base of the shoe into full bearing with the top of the pier. The bushings were then tap bolted to the web plates of the shoes. This arrangement kept the slack out of the connection when the reaction at the shoe changed from uplift to downward bearing with live loading only on the anchor spans.

After the cantilever traveler was erected, the gantry traveler and falsework were removed and taken to the other side of the river to be reused for erecting the south half of the bridge. The procedure used for constructing the south half of the structure was generally the same as that used for the north.

HAER No. PA-53
(Page 31)

The suspended span was closed at the center by a method using toggle and wedge devices that had been used in cantilever construction. during the ten year period prior to the time of this closure. The method was novel, but it was not unique for this particular operation.

". . . On May 15, 1911, the lower chord of the suspended span was closed by driving the pins at L23."(34) (Figure 10, Page 71) The following day the top chord was closed and the remaining web and bracing members were filled in. During this closing operation, the toggle and wedge devices were adjusted, which redistributed the stresses in the structure and the two cantilevered halves of the center span became one simple truss span suspended on the hangers at Panel Points 16 North and 16 South.

"During the entire work of erection, nothing of consequence occurred which has not been foreseen and provided for. There were no losses of either men or material and no serious injuries were reported.

HAER No. PA-53
(Page 32)

One man fell into the water, but was rescued without serious results."(35)

Engineering and Technological Significance

The Sewickley Bridge is significant in that it is representative of the type of bridge that was being built at the turn of the century. Also, as explained above, some novel and special details were used on the Sewickley Bridge during its design and construction. At the present time the structure is in an extremely poor physical condition requiring the imposition of stringent vehicle load and speed restrictions. There are, however, other highway bridges in the area which are quite similar in style and design but are in much better physical condition.

The Ambridge-Aliquippa Bridge (Appendix A), formerly known as the Ambridge-Woodlawn Bridge, also crosses the Ohio River and is located approximately 5 miles downstream from the Sewickley Bridge. The Ambridge-Aliquippa Bridge was built by Beaver County in 1926-1927

HAER No. PA-53
(Page 33)

as a 2-lane structure approximately 1,908 feet long, consisting of 5 through truss spans, 2 deck girder spans and 1 pony truss span.

An inspection, in 1976, resulted in the posting of a 10-ton maximum vehicle loading restriction on the structure. The load restriction was imposed primarily because of the poor condition of the truss bearings.(36) It was also noted in the report for this inspection that all four of the adjustable redundant eyebar members in the suspended center span trusses were permanently bowed because the members were inadvertently placed in compression at some time during the history of the structure.

It is anticipated that the bridge will be rehabilitated for unrestricted loading. This could require the replacing of bearings and twisted eyebars and the repairing of miscellaneous floor system elements.

The Rochester-Monaca Bridge (Appendix A), also located in Beaver County, carries L.R. 76 over the Ohio River from Monaca on the south to Rochester on

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the north. It is approximately 13 miles downstream from the Sewickley Bridge. The structure, built in 1930 by Beaver County, is a four-span cantilever through truss bridge 2,160 feet long center to center of end bearings and supports a 28'-0 wide roadway and a 9'-0 wide sidewalk on the upstream side.

The structure is generally considered to be in good condition and capable of carrying the modern AASHTO HS20-44 loading.(37)

The Bellaire Highway Bridge (Appendix A) spans the Ohio River between Bellaire, Ohio and Benwood, West Virginia, approximately 82 miles downstream from the Sewickley Bridge. The bridge was built in 1925 by the Interstate Bridge Company, a private toll company who remains its present owner. The structure was built principally for local vehicular and pedestrian traffic between the immediate communities of Bellaire and Benwood. At the present time the bridge handles approximately two million vehicles per year.

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The structure has always been a toll bridge with a major portion of the revenues received going toward maintenance and repairs. An in-depth inspection is made on the structure every 5 years. The structure is generally considered to be in good to excellent condition.

This bridge is almost an exact twin of the Sewickley Bridge except it is 100 feet shorter in total length and it is one-foot narrower.

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Page created: 18-Feb-2009
Last modified: 18-Feb-2009

HAER Text: Pennsylvania Department of Transportation, February 1978
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