The Penn Street Viaduct at Reading, PA is located at the foot of Penn Street. The viaduct begins at the west curb line of Second Street and extends westward a distance of 1,350 feet. When completed in 1913, the viaduct carried Penn Street across the Schuylkill River, the canal of the Schuylkill Navigation Company, the Schuylkill division of the Pennsylvania Railroad and two branches of the Philadelphia & Reading Railroad.
Work on the viaduct began on October 16, 1911. On Friday, November 14, 1913, the first trolley car passed over the bridge, starting from the east side at 5:14 PM.
The viaduct consists of a retained and reinforced concrete beam and slab approach, eight forty-eight-foot arches with a nine-foot rise; five one hundred and ten-foot elliptical arches, with a twenty-four-foot rise, and one forty-eight-foot elliptical arch, with a nine-foot rise. The width of the structure is eighty feet and the greatest height above the water is thirty-six feet.
The original roadway carried two standard gauge electric railway tracks. The trolley wires were carried by a line of iron pipe posts in the center of the bridge. Boulevard arc lamps were placed on alternate trolley poles and twenty-six clusters of tungsten electric lights were carried on concrete posts monolithic with the balustrades on each side of the structure. There were four lights to each cluster.
The viaduct replaced a steel bridge which was built in 1885. A matter that gave the engineers considerable concern was the fact that traffic across the river at the foot of Penn street had to be taken care of at all times.
Owing to the fact that the new structure was designed to be much wider than the old, it was arranged that the latter should remain in place until a part of the new bridge could be used. The specifications for the new structure provided that the contractor should "cut off the sidewalk on the downstream, or south side, of the old steel structure," and then build the southern one-third of the new viaduct. On this a temporary floor was placed and traffic was directed across this new portion. The old bridge was then removed and the remaining two-thirds of the new bridge was built. In this way it was necessary for the contractor to actually build two bridges side by side. This was successfully done and the casual observer will not notice that the structure was erected in this manner.
In the matter of bridge construction Berks County has always insisted on getting the very best. When the first Penn Street bridge project was started, there was great difficulty in getting the movement under way. When finally the structure was completed it was of the most up-to-date design. When the first bridge was swept away by flood, in 1850, it was replaced by a bridge of later pattern. When the time came to erect the third bridge the iron age had been reached and the structure was of that material and of the latest design.
Of necessity, therefore, the present bridge could not possibly have been anything but what it is, spacious and imposing and, above all, artistic in design.
The first intimation that the iron bridge across the Schuylkill River at the foot of Penn street was no longer safe came in the Spring of 1909, when employees of the Reading Transit Company, while repairing the tracks on the bridge, discovered that the girders at the point where the structure spanned the Pennsylvania Railroad tracks had deteriorated to such an extent that they were unsafe. Upon being notified of this condition of affairs, the County Commissioners had new girders placed at that point. This was done at a cost of $1,005.00, the bill being paid by the county June 10, 1909.
Later it was rumored that the entire structure was unsafe, and the County Commissioners ordered County Engineer Charles F. Sanders to make an investigation, which was begun August 12, 1910. After such investigation, Mr. Sanders condemned the structure as unsafe for present-day travel. On August 15 the Commissioners ordered Mr. Sanders to proceed to New York with his data and submit the same to a bridge expert.
Two days later the Commissioners took steps to regulate traffic over the structure. Trolley cars were not permitted to use the span over the Wilmington & Northern Railroad tracks, but passengers were transferred at that point. The following day the Reading Railway officials agreed to temporarily brace this portion of the bridge.
About this time suggestions were heard to the effect that the iron bridge should be replaced by a modern concrete structure. On August 27 the New York experts, who went over the data submitted by Mr. Sanders, condemned the bridge as unsafe for the travel of the present. Trolleys were now compelled to discontinue the use of the bridge, and watchmen were put on duty to prevent the structure from being overtaxed.
The matter of the advisability of erecting a new bridge was referred to the Grand Jury; and on September 17, 1910, that body reported that "insufficient data had been presented as to the cost of a new structure, the possible land damages to be incurred, and the actual condition of the present structure." On September 20 the County Commissioners ordered the bridge closed to vehicle traffic. On September 29, experts from Philadelphia, who had been called into consultation, reported that the bridge was only half as strong as it should be and that it was impractical to strengthen it. Meanwhile citizens proceeded to ask for an injunction restraining the Commissioners from keeping the bridge closed. This injunction was refused by the Court on October 3. On October 13, upon having received further advice from experts, and made minor repairs, the bridge was again opened to vehicle traffic, but trolley cars were not permitted to cross. However, prior to this, a footwalk was constructed in the center of the bridge, so that pedestrians crossed at this point and vehicles used the space on either side of the walk.
In December, 1910, the matter of erecting a new bridge was again submitted to the Grand Jury, which, on the 10th of that month, reported to Court, recommending a new structure. January 14, 1911, the Court approved this report.
The Commissioners were now free to proceed and conferences were held with city officials and representatives of the Reading Transit Company, the Pennsylvania, and Philadelphia & Reading railroad companies, the Schuylkill Navigation Company and the State Waterway Commission, all of whom were interested in the proposed new structure.
The next step was to secure the services of a Consulting Engineer. B. H. Davis, of New York, was the person selected for this service. County Engineer Sanders, with the assistance of Consulting Engineer Davis, and a corps of other engineers then proceeded to prepare the plans and specifications.
Now came the time to consider the matter of raising the necessary funds to pay for the new bridge. Several plans were suggested and discussed, but no final action was taken at that time.
By March, 1911, a tentative draft of the proposed new structure had been prepared, and was accepted by the County Commissioners. By this time it was definitely decided that the structure should be eighty feet wide. There was much discussion as to whether all property should be acquired from Court to Cherry street and a park established at this point, whether a sixty-foot street should be laid out on either side of the bridge approach, or, whether the structure should be built against the houses on either side of the street.
The second plan was finally adopted, and, at a conference between the City and County Officials, held April 28, 1911, it was agreed that the city should pay twenty-five per cent of the damages to property on either side of the bridge between Front and Second streets, and the county seventy-five per cent.
In addition, the agreement provided that the county should pay seventy-five per cent, of the cost of replacing the paving and curbing between Front and Second streets, the city to pay the remaining twenty-five per cent.
The plans provided for the raising of Penn street about eighteen inches at the intersection of Second Street. This necessitated taking up and' relaying the paving on South Second Street, Penn to Cherry, and re-macadamizing North Second Street, Penn to Court. Under the agreement the county assumed all responsibility as to the cost of this. In addition, the county agreed to pay the entire cost of replacing gas and water pipes and sewers wherever necessary on Penn and Second Streets.
After the contract for re-macadamizing North Second Street had been awarded the city agreed to pay the difference between the cost of macadam and wood block paving. Consequently, North Second Street to Court was paved with wood block.
On June 30, 1911, the County Controller advertised for bids for between 30,000 and 50,000 barrels of cement, to be used in the construction of the new bridge. On July 25 these bids were opened and the contract was awarded to the Allentown Portland Cement Company, for Evansville, Berks County, cement, at $1.24 a barrel.
Meanwhile, there were many attempts to arrive at the amount of damages to which Penn street property owners on either side of the bridge were entitled. On August 15, 1911, the advertisement asking for bids for the erection of the new bridge was inserted in the newspapers. The bids were opened September 14, 1911, and the contract awarded to L. H. Focht & Son for $325,910.00. The highest bid was $450,000.00.
On September 27, the Commissioners decided upon a bond issue of $475,000.00, at 3 1/2 per cent, interest, to pay for the new bridge, the damages, etc. Provision was made that part of the indebtedness was to be paid off each year, until at the end of twelve years the entire loan should be repaid.
October 16, 1911, work on the new bridge was actually begun.
The County Commissioners and city authorities, in order to fix the damages to which property owners were entitled because of the enterprise, appointed A. H. Kretz, William M. Zechman and Isaac Umbenhower as a Board of Appraisers. This Board reported November 28, 1911, and to their credit be it said, that later their figures were accepted, with one or two exceptions, and an amicable settlement was made with all property owners on the east side of the river, save two.
On March 6, 1912, the bridge bonds were received from the printers, the National Bank Note Company, of Philadelphia. Then followed the task of signing them, the signatures of each of the three County Commissioners, their clerk, and the County Controller being required to make them legal. On Friday, March 15, 1912, the bonds were placed on sale at the Reading National Bank. The sale of the bonds was a feature connected with the bridge project which gave the officials considerable concern, since those who knew the condition of the bond market repeatedly gave warning that the bonds could not be sold at par, since they bore only 3 1/2 per cent interest. Experience, however, proved that they were mistaken. The people of the county responded splendidly and bought the bonds more rapidly than the money was needed.
The building of the structure went forward with the usual incidental details and beyond the fact that the work did not progress as rapidly as was expected, there was little fault to find. Unlooked for difficulties were met, more especially in the matter of finding satisfactory foundations for some of the piers. In some instances it was necessary to go thirty to thirty-five feet deeper than the original borings showed, and, this, of course, caused some delay. On November 21, 1912, one-third of the new bridge was opened to traffic. Up to this time traffic had passed over the old structure. Work on removing the latter was now pushed, but it required another year before the northern two-thirds of the structure was completed.
On Friday, November 14, 1913, the first trolley car passed over the bridge, starting from the east side at 5:14 p. m. The new structure was now open to traffic of all kinds.
On February 2, 1914, the Court appointed Fred. H. Muhlenberg, Frank S. Stevens and John P. Charlton as viewers to pass upon the new structure, and Saturday, February 21, 1914, a favorable report was submitted to, and approved by the Court.
Fords and ferries were the original modes of public communication over the Schuylkill River between the eastern and western sections of Berks County.
These were extremely unsatisfactory, and very early there was agitation looking to the erection of a bridge.
The movement took definite shape in 1796, when the Grand Jury of the county, with the approval of the Court, voted $32,000 "out of the county stock" to erect a stone bridge over the Schuylkill at Penn Street, Reading. This sum was deemed inadequate, and an act of the Legislature was procured, authorizing a lottery to raise $60,000 for the purpose and appointing the County Commissioners and eight citizens to supervise it. This scheme was unsuccessful, and the act authorizing it was repealed in 1798, the money derived from the lottery being returned to the investors.
The project for the erection of a stone bridge having failed, petitions were presented to the Court in 1801, asking for the erection of a wooden bridge upon stone piers, at the estimated cost of six thousand pounds. This proposition having been referred to the Grand Jury by Judge Rush, President of the Court, the jury granted an appropriation of $16,000 for the purpose, to be assessed in three yearly payments.
This recommendation was approved by the Court and, accordingly, a contract was entered into which Obediah Osborn, of York County, from whom proper security was taken for its compliance, and work was begun the same year. After the expenditure of about $30,000 without substantial result other than the construction of four stone piers, one on either bank and two in the river, Osborn, in 1804, abandoned the contract. The Commissioners brought suit against the contractor's bondsmen. Osborn thereupon assigned all his property to the Commissioners and left the State. The property was sold by the Commissioners, thereby reducing their demand to about $8,000. The same year an act of the Legislature was passed remitting to the County its arrears for state taxes, amounting to some $5,000, as a contribution toward the completion of the bridge.
About this time the project for a stone bridge was revived, a petition of citizens being presented to the Court in January, 1805, to that end, submitting at the same time a plan for a structure of eight arches, two of thirty-seven feet each, two of fifty-six feet each, two of seventy feet each and two of eighty-four feet each, the breadth of the bridge to be thirty-six feet. The probable expense was estimated at 25,000 pounds. This project was also approved by the Grand Jury and the Court, though in view of previous experience, the raising of the required sum proved to be impracticable. Nothing seems to have been done toward the realization of this scheme for several years, and in the meantime the masonry of the piers, as well as the timber on hand, suffered from neglect.
By further legislative enactment in 1812 and 1814, authority was given to the County Commissioners to undertake the work of building the Penn Street Bridge, the latter act giving them the option to erect it of either stone, wood or chain. Accordingly the Commissioners entered into a contract with Lewis Wernwag and Joseph Johnson to erect the Penn Street Bridge, which it was determined should be of wood, built upon the piers erected previously by Osborn.
By the beginning of 1816 the bridge was so far completed that it was thrown open to public travel. The cost, according to the contract, was $43,760. The sum of $859 was expended for the erection of a toll house, $1,738 for painting the structure in 1817, and $3,116 for alterations and repairs in 1818, making the total cost about $50,000.
In January, 1816, the County Commissioners published the following schedule of tolls:
Foot passengers, one cent each.
Horses or mules, four cents each.
Horse and rider, six cents.
Score of sheep, six cents.
Score of hogs, ten cents.
Score of cattle, twenty cents.
Vehicles, according to the number of horses employed.
John Weldy was appointed toll gatherer.
The bridge was well constructed and, at the time, was considered a very handsome affair. External ornament was not neglected. Two wood-carved effigies, the one representing "Commerce" and the other, "Agriculture," were placed upon the pediments at either end of the bridge.
First Penn Street Bridge
A series of freshets in the Schuylkill River entailed great financial loss to the county in the destruction, in whole or in part, of the various bridges spanning that stream. In January, 1839, the water rose 17 feet above the ordinary level, sweeping away the Poplar Neck Bridge and severely damaging the Lancaster Bridge. The Penn Street Bridge successfully withstood the force of the waters, which reached to within two feet of its floor, and drove a number of canal boats against the structure and its abutments. In January, 1841, the water rose 19 feet, doing considerable damage, but leaving the bridges comparatively uninjured. In July, 1850, there was a rise of the water to about the same height as in the freshet of 1841. This was followed in the month of September, of the same year, with the most disastrous of all the freshets up to that date. The rise was about twenty-five feet, and, as a result, the Penn street, the Lancaster and Poplar Neck bridges were swept away, together with every other bridge on the Schuylkill within the County limits. In the following year legislation was procured, authorizing the rebuilding of the bridges by the County, and the Commissioners contracted for their construction with the following persons at the sums named:
Penn Street, Hoyer & Bitner, $17,000.
Lancaster, Simon Hoyer, $11,000.
Poplar Neck, David Renno, $7,500.
Hamburg, Jacob Ahrens, $5,400.
Second Penn Street Bridge
In October, 1869, the flood reached a height of twenty-three feet above low water mark, the water extending up Penn street to Second. One span was destroyed of each of the Lancaster and Poplar Neck bridges, but the Penn street structure was unharmed.
The legislation, under which the bridge was erected, contained a provision requiring the County Commissioners to file in the Court of Quarter Sessions an annual statement of the amount of tolls received, and, that, whenever the tolls reimbursed the expenditures, the bridge should be declared free. A similar provision had been made in all prior bridge legislation.
In 1848 an ineffectual effort was made by application to the Court to have the Penn Street bridge declared free, the County Commissioners resisting the application on the ground that the requisite conditions had not been complied with. In 1883, the application was renewed with success, and thereupon all county bridges over the Schuylkill became exempt from toll.
Upon the construction of the Pennsylvania Schuylkill Valley Railroad, in 1884, that company, in order to facilitate its right of way, removed the wooden covered bridge at the foot of Penn street and replaced it with an iron bridge on the original piers, slightly elevated, at a cost of $100,000, the County contributing one-third of that amount. A material item was the construction of the eastern approach, which required to be lengthened and elevated to permit the location of the trackway beneath, along the bed of the canal.
In 1895, the Reading Traction Company, upon obtaining from the County the right to cross the bridge with its tracks, repaired and strengthened the structure to accommodate it for such use.
The Penn Street reinforced concrete viaduct 1,350 ft. long by 80 ft. wide was built under rather unusual conditions. When completed in 1913, the viaduct carried Penn Street across the Schuylkill River, the canal of the Schuylkill Navigation Company, the Schuylkill division of the Pennsylvania Railroad and two branches of the Philadelphia & Reading Railroad. The viaduct replaced a steel bridge which was built in 1885.
Old Iron Bridge
The old steel structure was of the Pratt truss type with a masonry approach at the east end and an earth fill at the west end. The total length was about 1,128 ft., the river spans being 200 ft. long. It was built in 1885 and was designed merely for ordinary highway traffic. However, with the development of the western section of the city a considerable increase of traffic resulted and a traction company proceeded to lay tracks and run cars across the bridge without taking adequate measures to strengthen the structure.
When the danger arising from such a condition was brought to the attention of the county commissioners they made an investigation which showed that the structure was seriously overstressed. Subsequent to this investigation the street car traffic was abandoned and the bridge restricted to ordinary highway traffic. To relieve the conditions caused by such a curtailment of traffic accommodations it was decided to build a reinforced concrete viaduct.
The viaduct has fourteen arches, five of 110-ft. span and nine of 48-ft. span. At the east end there is a reinforced concrete approach supported on columns, while the arches at the west end connect directly with the street grade.
The center line of the viaduct coincides with that of the old steel bridge. One of the problems of construction was to build the new structure without seriously interfering with traffic on the old one. The situation was further complicated by the three railroad crossings, all of which had to be kept clear of any obstructions interfering with the operation of trains. The new viaduct was designed for a total width considerably in excess of that of the old one, which made it possible to build a part of the new viaduct 24 ft. wide for its entire length by removing the downstream sidewalk of the old steel bridge. In this way traffic was handled without serious inconvenience. When the 24-ft. section was completed it was put in service, and the old bridge was dismantled and the remaining section of the viaduct built. A timber deck with board fences on either side was placed on the completed arched sections to care for the traffic.
Centerline of the viaduct coinsides with that of the old steel bridge.
The foundations for the thirteen piers and the two abutments are, in part, supported by pedestal piles and, in part, are carried directly to an excellent bed of rock found at an average depth of about 10 ft. below ordinary low water in the river. The five 110-ft. spans across the river and the canal have their piers carried to rock in all cases. The river piers were built in three independent sections each supporting an arch rib. They have spread footings of widths varying with the conditions. Both end sections are pointed; the upstream section in each case being equipped with an ice breaker. Between these sections heavy reinforced concrete curtain walls 2 ft. thick were built. These extend from the tops of the footings to the springing line of the arches, thus giving the construction the appearance of a solid pier. This design was adopted partly to prevent the collection of drift in time of flood and partly for the sake of appearance.
The pier sections are reinforced with 1-in. square vertical bars spaced 18 in. on centers and 3/4-in. horizontal bars spaced 2 ft. on centers. This reinforcement is a continuation of that of the arch ribs to which it is bonded. One of the piers is located about 35 ft. from the east bank of the old canal and this condition necessitated dredging a new channel on the west side of the pier.
Abutment piers, of a heavier section than the intermediate ones, were placed at either end of the five 110-ft. spans. They were designed to provide for the excess of thrust from the large spans over the lighter thrust of the adjacent smaller ones. They were likewise built in three independent sections, though not connected as in the case of the river piers, and are carried to rock foundation. At the point where the viaduct crosses the tracks of the Pennsylvania Railroad the proximity of the station necessitated a modification of the design for the other piers. This was accomplished by building arches, each with an 18-ft. span and a 4-ft. rise, between the sections of the pier located adjacent to the station.
The east end of the bridge is made up of a series of arch rings with 48-ft. spans and the piers supporting them are solid for the entire width of the structure. These piers are drained by means of 4-in. terra cotta pipes with outlets at ground level.
Arch Crossing Railroad Tracks
The eastern approach to the structure is carried on a series of concrete columns and curtain walls supported by MacArthur pedestal piles, about 25 ft. long, driven to rock. The columns are built directly on the pile sections. They are spaced 11 ft. on centers longitudinally, and are tied together with heavy concrete beams 16 in. wide and 3 ft. deep. The latter are reinforced continuously with seven 1-in. bars, in the bottom section, supplemented by vertical stirrups. The 12-in. reinforced concrete floor slab is carried directly on these beams. At the foot of the approach, about 80 ft. from Second Street, there is a transverse retaining wall about 6 ft. high and the remainder of the approach is a rock fill with light retaining walls on either side.
The main arch spans are made up of three arch ribs tied together with transverse spandrel walls, the latter supporting the floor system of the bridge. The middle arch rib is 16 ft. wide and the two outer ones are each 10 ft. wide. The curve of the intrados is an ellipse with a clear span of 110-ft. and a rise of 24 ft. The thickness of the center rib at the crown is 3 ft. 6 in. and that of both outside ribs 2 ft. 9 in. The thickness at the haunches is approximately 7 ft. These ribs are reinforced as shown in the accompanying drawing. Spandrel walls 2 ft. thick are placed at intervals on the arch ribs, the height of these walls depending upon their position in the structure. The 12-in. floor slab is supported directly on these spandrel walls.
The 48-ft. arches are likewise elliptical and each has a rise of 9 ft. 6 in. and a crown thickness of 1-ft. 5 in. The reinforcement is of the same type as that used in the larger arches. No stirrups are used in this reinforcement and all rods are lapped at least forty diameters.
The structure has a 55-ft. roadway and two 12-ft. 6-in. sidewalks. In the center of the 55-ft. roadway provisions were made for two trolley tracks and terra cotta thimbles placed in the concrete section of the floor system for the trolley poles. The surface of the original roadway was a 3-1/2-in. creosoted wooden block pavement laid on a sand cushion, resting on a concrete base. The top surface of the floor slabs and the extrados of the 48-ft. arches are waterproofed with a four-ply layer of Hydrex felt. The sidewalks are given a 3/4-in. surfacing made up of one part of cement and two parts of sand and the curb lines are protected with Wainwright curb bars.
On each side of the bridge there is an ornamental reinforced concrete railing with posts for lighting purposes. These posts are placed above alternate piers in the short spans and at the middle of the longer spans. The wires are carried in terra cotta conduits below the sidewalks.
The bridge is built on a rising grade from each end to the river spans, the grade from the east being 2.65 per cent and from the west 2.00 per cent. The west approach connects with a macadam roadway having a 3 per cent grade, and this roadway is given a crown of 6 in.
The piers were constructed in open caissons from a timber trestle built on the upstream side of the steel bridge. An industrial railway was laid on this trestle with spurs extending to the different piers, and when the arch sections were started a cableway was installed immediately below the downstream side of the steel structure. The cableway had a span of 750 ft. and was used for erecting the steel centers and placing the concrete in all of the arch sections within its range. The east approach of the structure and those arches east of the cableway tower were built by means of a traveling derrick. This derrick handled the construction materials required for the falsework and also the concrete from the 3/4-yd. Smith mixer used on that end of the work.
The concrete plant supplying the cableway was located on the west bank of the river a short distance upstream from the end of the old bridge. It consisted of two Mc-Kelvey 3/4-yd. mixers supplied by gravity from wooden material platforms. The sand used was brought in by cars on a spur track of the Reading railroad to a point easily accessible from the concreting plant, and the limestone was obtained from a quarry adjacent to the site. Owing to these favorable conditions, the cost of handling material was decidedly reduced.
An industrial track extended from the cableway tower to the concrete mixers and the concrete was handled on this track in 1 1/2-yd. Koppel cars by means of a continuous cable connected with a hoisting engine. This cable carried the empty cars into a position in front of the mixer and returned the loaded ones to the cableway. In this way the amount of concrete placed depended upon the speed with which it could be handled by the cableway.
Falsework and Centering
The falsework and centering for the 48-ft. arches, except in the case of the arch across the Reading track, on the east side of the river, was of the ordinary wooden type. For the exceptional case the need of adequate clearance for the full span required a special design. The centering for the 110-ft. arches consists of trussed steel arch sections hinged at the crown and held together by horizontal tie rods. These tie rods are provided with turnbuckles which enable slight discrepancies in the position of the centering to be corrected without resorting to the use of wedges. The ribs are supported on wooden sills resting on oak lowering wedges carried by steel I-beams. The I-beams are in turn carried on steel columns supported on the top footing courses of the piers.
In all of the form work, good quality, planed, well-matched yellow pine lumber was used and particular attention was given to securing good workmanship.
The reinforcing bars are of Corrugated and Mono types furnished by the Philadelphia Steel and Wire Company under a contract which calls for the placing of all steel in the forms. The bars in the arch rings are about 34 ft. long and are carried through holes bored in the bulkheads of the forms, thus holding the steel to its proper position in the concrete section.
Three different concrete mixes were used. That in the piers and footings is I:13:6, that in the arch ring, spandrel walls and floor is I:2:4, and that in the balustrade and lampposts, I:2:3. The exposed concrete surfaces are bush-hammered and the edges are chamfered. Allentown Portland cement was used throughout the work.
The construction was carried out under the direction of Mr. Charles F. Sanders, county engineer, and of Mr. B. H. Davis, who, as consulting engineer, also designed the viaduct. Messrs. L. H. Focht & Son, of Reading, Pa., were the contractors.
In 2016 work began to rehabilitate the 104-year-old viaduct. The repairs will include replacing floor beams, repaving the roadway and replacing crumbling concrete railings.