The Pecos Viaduct

The completed Pecos Viaduct of 1892.

Robert J. Sporleder photo album 1896

The Pecos High Bridge may be the most famous of all the historic bridges in Texas. In 1892, it held the distinction of being not only the highest bridge in the United States, but also, at 322 feet 10 3/4 inches in height, the third highest bridge in the world. Strengthened in 1910 and 1929, this bridge was in continuous service as part of the nation's first southern transcontinental railroad until it was replaced by a newer one during World War II. Known to railway historians as the Pecos Viaduct, this bridge was the second across the Pecos and was designed to solve a host of problems that had plagued the Galveston, Harrisburg and San Antonio Railway since the line opened in 1883.

The crossing of the Pecos River had been the single biggest engineering obstacle encountered during construction of the Texas leg of the first southern transcontinental railroad. The first crossing was accomplished by using a simple iron "fair-weather" truss-bridge, located at the bottom of the canyon at the confluence of the Pecos and the Rio Grande.

The track winding down into and out of the canyon to the first bridge left the flat uplands 5-6 miles distant from either side of the bridge. Following the sinuous canyon rim in a series of curvy and steep grades crossing numerous deep intervening side canyons, the track descended to the bridge. In some sections the grade consisted of no more than a narrow ledge blasted into the towering cliff walls. So prone were these to rock falls that the railway company had to employ "track-walkers" both night and day to prevent derailments caused by obstacles on the road bed.

The first crossing of the Pecos River had been incredibly expensive to construct and was proving to be quite costly to operate and maintain. Steep grades and degrees of curvature combined to impose severe length and weight restrictions on all trains using this section of track. It was necessary that two tunnels -both in excess of 1,500 feet in length- be blasted through solid rock. In addition, 3,600 feet of wooden trestle and 2,730 feet of iron trestle works were also required. Perhaps the most significant aspect was that the original configuration of the route effectively limited future profitability at a time when trains were getting longer, larger, and carrying greater weights.

 

Construction of the Pecos Viaduct.

Courtesy Lehigh University

In 1890, Major James Converse, General Superintendent and Chief Engineer of the Line, made several reconnaissances along the Pecos River valley to identify potential locations for a new crossing. Converse is generally credited with first envisioning the Pecos canyon crossing on a high viaduct and with preparing the initial designs for the bridge about 5 miles up river from the first one. By late 1890, Julius Kruttschnitt, General Manager and Chief Engineer of the Texas and Louisiana lines of the Southern Pacific System, approved the designs, with minor changes, for the Pecos Viaduct. Kruttschnitt contracted with the Phoenix Bridge Company to provide bridge materials and crews for construction of Converse's designs. When completed, the new crossing would eliminate 11 miles of steep and curvy grades in and out of the Rio Grande canyon as well as closing the station houses at Helmut, Painted Cave, and Flanders Stations.

By February, 1891, Ricker, Lee, and Company received the contract for pier and footer construction and for building the approaching grading to the new bridge. The piers supporting the bridge were made from concrete and local limestone cut from the canyon bottom and floated into place. Seven of the most important footings had copings cut from Texas pink granite from the Granite Mountain Quarry in Burnet County more than 200 miles from the construction site. All piers and footings were constructed on bedrock. It was often difficult for the engineers to determine exactly its location due to the accumulations of river deposits and boulders in the bottom of the canyon. Pier number nine was the most difficult to construct because of these deposits. Although the pier was 55 feet in overall height, only about five feet of it was visible at the surface. By the end of October 1891, the footers and piers were completed: Ricker, Lee, and Company then turned their attention to constructing the grades and new track leading to the east and west sides of the canyon rim.

The Phoenix Bridge Company of Phoenixville, Pennsylvania began work on the bridge's iron and steel towers and spans on November 3, 1891, under the direction of Chief Engineer J. T. Mahl. No heavy locomotive cranes existed at this time, so engineers designed an apparatus called a "traveler" to lower the heavy iron beams into place. This strange looking device (Figure 2) utilized an overhanging arm that was 124.6 feet in length, greater than any traveler ever used before (Wilson 1925:29), to lower bridge sections into place. This arm was counter-balanced by the 57 foot wheelbase of the traveler, clamped to the completed section of bridge during operation. The various sections of bridgeworks were assembled on both sides of the river adjacent to the track and then lowered into place by the traveler. The bridge sections included two cantilever arms, 85 feet in length; four tower spans, each 35 feet in length; two lever arms, 52.6 feet in length; one suspended lattice span, 80 feet in length; eight lattice spans, 65 feet in length; one plate girder span, 45 feet in length; and 34 plate girder spans, each 35 feet in length (ibid).

 

Construction of the Pecos High Bridge nears completion

Courtesy Whitehead Museum

The traveler began work from the east canyon rim lowering sections of bridgeworks down into the canyon. When the machine reached the approximate mid-point of the future bridge, it backed up and returned to the east canyon rim, was dismantled, loaded on a railcar, and hauled via the old rail route, across the bridge at the mouth of the Pecos, and on to the west canyon rim where it was reassembled and put to work again building towards the span that had been completed from the east side. Using a daily work crew that averaged 67 people, the bridge was completed in just 103 days at a cost of $250,108.00. The completed construction was 2,180 feet long, consisting of a combined cantilever and a 185-foot section of "suspended" lattice over the actual watercourse. The ironwork alone weighed 1,820 tons. With its completion, all that remained to bring the structure into service was the installation of the electrical signaling equipment on both approaches to it. Trains approaching from either way would be required to stop and inspect the bridge prior to crossing. On March 31, 1892, a special train carrying railroad dignitaries officially opened the Pecos Viaduct to regular rail traffic.

The railway company assigned a full-time watchman at the bridge once regular service began. His duties included patrolling the bridge at night for reasons of safety and performing regular maintenance and safety checks of the towers and superstructure. The watchman lived in a small two-room wooden house located just north of the tracks on the east side of the Pecos canyon. From 1893 to 1924, the watchman was W.A. Clare; the last watchman and pump operator to live in the house in the 1940s was a Mr. Carter whose widow still lived in Comstock, Texas in 1992.

The Pecos Viaduct was rapidly becoming obsolete by 1910 due to an ever increasing amount of traffic and the demands of heavier loads. The railway company substantially reinforced the original bridge design with an additional 2,268,786 pounds of steel -bringing the total amount of steel to an estimated at 5,497,063 pounds. The grades approaching the bridge from both sides were shortened a total of 665 feet by adding fill at each end. In 1929 additional structural changes were made that significantly increased the load capacity for trains crossing the viaduct.

In 1922, the Southern Pacific built a station on the east side of the Pecos River adjacent to the bridge. Although it has received scant attention in the literature, this facility was considered, at the time, to be a remarkable piece of engineering. The station consisted of a residence, pumping station, oil, and two water storage tanks. The pump house was located near the watchman's residence in the canyon bottom at the base of the bridge. Water for drinking and boiler purposes was pumped up from the canyon bottom to storage tanks on the east canyon rim The brackish waters of the Pecos were not suitable for the railroad's needs so a natural spring was used as the sole water source.

The watchman's 2 room residence and the pumphouse were both located on the canyon floor, well below the floodplain adjacent to the east side of the canyon. Though it is estimated that elevation on the floodplain on which these structures were built was roughly 1070-1080 feet above mean sea level (AMSL). However, these structures were inundated by flash flood waters on at least three different occasions between 1922 and 1960. Adjacent to the abandoned pumphouse pipeline which runs up the canyon cliff face there is a U.S.G.S. brass monument. The monument commemorates the June 1954 flash flood on the Pecos when waters rose over 80 feet above normal flow to an elevation of 1154.56 AMSL. Since 1969, the waters of Amistad Reservoir have permanently flooded this section of the Pecos River Valley to an elevation that averages 1117.0 AMSL. During a severe reservoir draw-down in 1988, the lake level dropped nearly 30 feet (1090 AMSL) exposing the upper portions of the pump house.

 

Masonry footings from the original Pecos Viaduct are still visible by boat on the Pecos.

NPS photo

The Pecos Viaduct was built almost entirely of metal to reduce the risk of fire. What little wood existed, such as the ties and decking, was covered with galvanized iron plating. In 1922, the railway company added 13 fire hydrants evenly spaced along the bridge decking to further reduce the risk of fire. The water source for the fire hydrants was a separate line from the same the pumping system. If water could not be pumped from the canyon bottom, there were two large water storage tanks to draw from.

The Japanese attack on Pearl Harbor on December 7, 1941, had repercussions that were felt as far away at the Pecos River Viaduct. Because of the bridge's strategic importance as part of the southern transcontinental railroad, the U.S. Army stationed troops at the Pecos River to protect security for the bridge and the increase in military rail traffic following the Japanese attack. During World I, the U.S. Army had stationed troops for a similar purpose, and, during the Mexican Revolution of 1917, Texas Rangers patrolled the bridge looking for saboteurs. Railways officials and the Office of Defense Transportation soon realized that the 48 year old bridge might be unable to carry all the weight it could be called on to bear, thus creating a bottleneck when the nation was rapidly mobilizing for war.

Topographic studies by the U.S. Army Corps of Engineers in 1942 identified a suitable site for a new bridge located less than one-quarter mile south of the existing Pecos River viaduct. The War Production Board placed a high priority on building a new structure, thus enabling the railway company to obtain the needed steel at a time when it was in short supply. By the end of 1942, the Southern Pacific had successfully applied to the Office of Defense Transportation and received construction materials for the new bridge which was to consist of a number of continuous cantilever and plate girder spans perched on top of two huge concrete towers anchored in the river bottom. Work began on the piers in August 1943; and on December 21, 1944, the 1.2 million dollar bridge was completed and in service as the first regular freight train crossed the 1,390 foot long structure. Still in operation today, it is commonly known at the Pecos High Bridge.

 

The Pecos Viaduct in its final phases of construction.

Courtesy Lehigh Museum

During the war years, the U.S. Army leased roughly 30 acres of private land on both sides of the Pecos River adjacent to the bridge. The Army established a military police camp which patrolled the bridge and canyon below both day and night. The foundation remains for several small buildings and the several limestone block machine-gun nests are all that remains of the Army's World War II presence at the bridge.

The 1890's Pecos Viaduct was kept as a standby for nearly five years following the completion of the new bridge. In 1949, the Southern Pacific contracted with the Robinson Erection Company (St. Louis, Missouri) to dismantle the historic bridge. Initially, the Southern Pacific had made plans for the purchase of the entire structure by the government of Guatemala for use in that country. Current literature on the subject provides conflicting stories on the fate of the old bridge. The Odessa News (October 15, 1978) states that the bridge was in fact sold to Guatemala, and, is still in operation in that country today. A post card of the 1892 bridge (Old West Collectors Series No. 46) states that "Because it was so well engineered the West Texas bridge was dismantled after 56 years [1948] and rebuilt across the Wabash River in Indiana." T.L. Baker writes that, initially, the Southern Pacific had made plans to sell the bridge to the government of Guatemala; however, the deal fell through resulting in the piecemeal sale of individual spans from the bridge to several different states and local governments for use as shorter bridges across streams within their political jurisdictions. Most of the other pieces and parts were sold to scrap metal dealers.