Pennsylvania Turnpike Reconstruction
Location: Somerset & Bedford Counties, Pennsylvania
Client: Pennsylvania Turnpike Commission
JMT leads the design to reconstruct and widen nine miles of the
As part of a large-scale project to reconstruct and widen the
Pennsylvania Turnpike, JMT is leading a team to design a nine-mile
section of the turnpike that passes through the Borough of New
Construction of the Pennsylvania Turnpike in the 1940s caused a
landslide - now referred to as the New Baltimore Slide -
approximately 4.5 miles east of the Allegheny Tunnel, and it
continues to affect local conditions.
The mass of rock and soil is 800 feet wide and extends 1,100
feet upslope from the roadway, and it has been moving slowly ever
since the original construction. The slide has been measured and
monitored through the years to ensure the safety of the travelers
along the Turnpike.
The scope of the project is to completely reconstruct the
roadway, widen it to six lanes with a 26-foot median, eliminate
most curves that exceed 3 degrees, address geotechnical issues at
the slide by excavating below the failure plane, and replace all of
the overhead bridges. In addition, all activities are to be
performed while maintaining a minimum of two lanes of traffic in
The most challenging aspect of the design has been determining
how to address the New Baltimore Slide. The Pennsylvania Turnpike
Commission (PTC) has monitored the movement and performed
ongoing repairs of the roadway shoulder at the base of the slide as
the mass moves and upheaves the pavement.
Early in the design phase, the team began a geotechnical
exploration program to continue the monitoring work that preceded
this project. Prior monitoring by the PTC included
inclinometers, core borings, and conventional field surveys to
develop structure contours of the failure plane, delineate the
boundary of the slide, determine the rate of movements, and
understand the trend of movements in relation to rainfall
events. The goal of the program is to understand how this
mass is moving in order to develop plans and specifications to
allow for the safe and efficient removal of the slide.
The estimated overall cost of this project exceeds $250 million
and will be constructed through several separate contracts.
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