History of the Armstrong Tunnel
The Armstrong Tunnel, opened in 1927, connects Second Avenue, at the South Tenth Street Bridge, to Forbes Avenue between Boyd Street and Chatham Square. The twin-bore four-lane tunnel passes under the Bluff (Boyd's Hill/Duquesne University) and vehicular traffic averages more than 11,000 drivers each day. Approaching the 100-year mark, this notable Pittsburgh tunnel was listed as a historic landmark in 1986.
A Tunnel Is Needed
When Pittsburgh annexed the town of Birmingham (South Side) in 1872, the need arose for better access to the southern shore of the Monongahela River. Most traffic relied on the Smithfield Street Bridge and an old wooden covered bridge at South Tenth Street. Travelers to the Bluff relied on the Fort Pitt Incline, which opened in 1882.
Increasing vehicular traffic necessitated that the aging wooden structure be replaced with a metal through truss bridge in 1904. When the incline closed in 1906, city steps were built for commuters to reach the heights, but a serious traffic bottleneck was developing for motorists to reach the heights or just get around the mountainous Bluff.
A proposal by Joseph G. Armstrong in 1908 to open a passage under Boyd's Hill was seen as a way to relieve traffic in the upper Triangle and increase access to both the northern side of the Bluff and, conversely, for travelers in the opposite direction to reach the South Side.
Armstrong's Dream Becomes Reality
The tunnel portals were designed by City Architect Stanley L. Roush, and Vernon R. Covell of the Allegheny County Public Works Department was the chief engineer. Booth and Flinn, Ltd., the company that had recently completed the Liberty Tunnels, was awarded the $1,600,000 contract, paid for by the $29 million County Bond Issue of April, 1926. The boring of the 1437 foot tubes began on January 18, 1926.
The east tube was holed through in six months and the west tube through likewise in record time. A total of 2800 feet, over one-half mile, driven in less than ten months. During the excavation work, over 80,000 cubic yards of earth and rock were removed.
On November 4, 1926, the crews boring the second tunnel tube broke through the final rock to complete the excavation process. The tunnels were officially dedicated on November 6, 1926.
Pittsburgh's new engineering marvel was named in honor of County Commissioner Joseph G. Armstrong, who had previously served as a member of the Select Council, Coroner (1905-1909), Director of Public Works (1909), Mayor of Pittsburgh (1914-1918), County Treasurer (1919-1923). This was followed by a trip through the tubes by county and city officials.
A lifelong South Side resident, the tunnel had been a dream of his for a quarter century. At a banquet that evening at the South Side Market House, a huge cake that was a replica of the North Portal was inscribed "Armstrong's Dream of 25 Years."
The anticipated opening of the tunnels was delayed for six months due to design changes brought on by frequent landslides at the Second Avenue end. The Southern Portals were extended outward beyond the rock face and winged walls were added. Additional protection included posts and chains in fence form which were erected at both ends of the tubes.
The ribbon-cutting ceremony for the new tunnel was held on May 25, 1927. The ceremony started with a parade forming at South Twelfth and Bingham Streets.
More than 1,000 persons in 300 automobiles, with two bands in line and headed by a squad of motorcycle police, paraded across the Tenth Street Bridge and through the tunnels.
Commissioner Armstrong cut the ribbon barriers at both ends of the twin tubes and duplicate dedication tablets at were unveiled at each portal.
The Armstrong Tunnel was the second vehicular and pedestrian tunnel completed in Pittsburgh. The total cost was $1,539,000. In addition, the county paid out $100,000 in blast damages to residents atop the bluff.
The 45-Degree Angle
The Armstrong Tunnel portals feature Italian Renaissance sandstone walls and cut-stone portals, trimmed with granite. The tunnel vault is concrete and includes a pedestrian walkway on the western side.
There is no ventilation system installed. Engineers reasoned that the short length of the tunnels, coupled by both a natural air flow and a push by truck traffic would be sufficient to keep the tubes clear of a buildup of toxic exhaust fumes.
The tubes are noted for the 45-degree curve in the twin horseshoe design. Originally envisioned as a straight passage, the bend near the Forbes Avenue portal was the unforeseen result of several factors: mines, geological factors, property rights and alignment with existing roads. When it opened, these twin tubes were the first curved vehicular tunnels in the world.
Almost from the first day of operation, the Armstrong Tunnel has been plagued by water seepage from the natural springs in the hill above the eastern tube.
Water made its way through joints in the reinforced concrete and began a steady trickle along the wall near the Second Avenue entrance. Six months after the grand opening, contractor Booth and Flinn was back at the tunnel making repairs.
Tile drains were installed in the sides and roof at that point in the tube. The repairs took a year to complete, and each tube was closed for six months at a time.
The drains provided some relief, but the seepage problem has persisted to this day to some degree. During prolonged stretches of sub-freezing weather, it is common for a large chunk of ice to form on the eastern wall from near the roof to the road surface.
A New Bridge Is Needed
With the increase of traffic brought by the Armstrong Tunnels, the city was forced to make an estimated $62,000 in repairs to make the 1904 10th Street truss bridge at the southern portal safe for normal traffic. An 11,000 pound restriction was placed on vehicles.
Proposals were put forth for a new South Tenth Street Bridge to replace the antiquated truss bridge. The new span was constructed in 1931/1932, and is Pittsburgh's only conventional triple span cable suspension river bridge, a design that resembles the iconic Golden State Bridge.
The Hidden South Portal
The southern portals of the Armstrong Tunnels, with its stone facing and granite lining, became a familiar site to travelers making their way across the river or along Second Avenue. They remained a constant visual piece of the south face of the Bluff for thirty years.
In April 1958, during the construction of the Penn-Lincoln Parkway, an elevated section of the westbound lanes and the Second Avenue ramp were constructed directly in front of the tunnels, forever obscuring the vintage portals from view.
Dark And Dirty Elephant
The lack of ventilation inside the tunnels and the constant buildup of dirt and grime soon turned the Armstrong Tunnel into what became refered to as Pittsburgh's "dark and dirty elephant." The overhead string of lights also began to deteriorate, and the dimly lit gray walls forced motorists to turn on their lights upon entering.
One city engineer, shortly after the tunnel opening quipped, "One nice thing about it being dark and crooked is that no one will try to speed through it, so we might say it is automatically accident-proof."
A number of vehicular mishaps over the years convincingly disproved the tongue-in-cheek theory about the tunnel being accident free, but the dark and dreary atmosphere inside the tubes were a growing concern for motorists and pedestrians alike.
Despite the deteriorating situation and frequent calls for improvement over several decades, no action was taken. In the meantime, City Council and the County Commissioners continued their decades long debate as to which party was responsible for tunnel maintenance. It was not until the late-1980s that these issues were addressed with the help of federal funding.
One exception when the tunnels were thoroughly cleaned occurred in 1940. President Franklin D. Roosevelt visited Pittsburgh on October 19. The route of the presidential motorcade passed through the tunnels. A week prior to the visit, the "notoriously filthy tubes" were swept out and the walls washed.
Catch The Show
The Armstrong Tunnel may have gained a reputation as a dark and dank traffic route to avoid if necessary, but the South Portals were often a gathering place for curious onlookers and fans of Pittsburgh's dancing traffic policeman Vic Cianca.
Officer Cianca's animated gestures, cool demeanor and personal touch in directing traffic earned national attention and a spot on the hit TV show "Candid Camera." Cianca was not always stationed at the Second Avenue, 10th Street Bridge and tunnel portal intersection, but when he was it was a good bet that a crowd would gather to catch the show.
In 1988, plans were put in place for a $3.8 million rehabilitation of the cave-like twin tunnels. The 18-month project involved the installation of new lighting, adding reflective panels along the tunnel walls to increase illumination, drainage system overhaul, and a new sub-base and concrete road surface. Jersey barriers were installed along with a wall along the pedestrian walkway.
The project began in October 1989 when the outbound (west) tube was closed for ten months, followed by an eight month closure of the inbound (east) tube.
Tedesco Contracting Corporation cited that one of the main problems during the rehabilitation was locating craftsmen qualified to set the ceramic tile in mortar along the gray stone walls, a skill that was rapidly becoming a lost art. The project was officially completed on May 28, 1991.
Thirty-two years later, in March 2023, the venerable tubes were once again due for some necessary repairs. The $13.1 million project maintenance will address water seepage and concrete repairs, removal of the ceramic tile liner, replacement of aging light fixtures, and the installation of fireproof wall panels.
The inbound tunnel will be closed through the winter of 2024, followed by work on the outbound side, which will last until the spring of 2025.
The View From Above
The Urban Myth Debunked
An urban legend states that the 45-degree bend in the tunnel was a mistake and that Chief Engineer Covell committed suicide in shame. THIS IS NOT TRUE.
Vernon Covell lived to build again. As for the curve being a mistake, it's highly doubtful the engineers could have been off by that much without being aware of it.
The general belief is that path was designed to thread its way between and below existing and proposed university buildings. To this day, University architects have been careful in their planning so as not to damage the historic tunnel.
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