The 52 Allentown line offers peak hour service
between South Hills Junction and Gateway on a route that takes the
hillsides, rather than using the Mt. Washington Transit Tunnel.
The trackage provides an emergency backup in case the tunnel needs
to be closed, and serves Allentown and other old neighborhoods along
the way. There are some fine views across the Monongahela
toward downtown and other parts of Pittsburgh.
In this view the day's first inbound afternoon train is descending to
reach Panhandle Bridge. The southern highway approach to
busy Liberty Bridge is visible in the background, and below the
train the viaduct for the much more commonly used "T" light rail tunnel route appears.