Tilghman Street Bridge Under Construction looking southest from the east side of the Lehigh River. Note the cranes and construction rafts in the river. The Tilghman Street Viaduct was the first bridge in Allentown built exclusively for motor vehicle traffic. When it opened in 1929, it opened up access to the East part of Allentown. This photograph shows the construction of the massive concrete arches of the bridge, first used in the construction of the Eighth Street Bridge in the 1910s.