Photo Courtesy Johnson, Mirmiran & Thompson

The new four-level interchange replaces left-lane exits and entrances within the existing braided interchange design. Barriers will separate general-purpose lanes from express toll lanes, but all interchange movements will be provided from both sets of lanes.

Since the managed lanes and general-purpose lanes had to be barrier separated through the interchange, each exit movement required two separate ramps, one for the managed lanes and one for the general-purpose lanes.

To achieve this, JMT designed an interchange with multiple movements on top of an existing interchange that carried existing traffic during construction.

To facilitate maintenance of traffic, the decision was made to segment the construction into two contracts.

JMT was challenged with a 10-month design schedule. At the peak of design work, 109 JMT employees worked on this project.

Key Players

Owner: Maryland Transportation Authority
Contractor: G.A. & F.C. Wagman/Corman Construction/McLean Contracting Co. (Joint Venture), Maryland Transportation Authority
Engineers: Johnson, Mirmiran & Thompson