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Project Information

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County:Calvert Project Number:SM351_11
Project Name:
MD 4, Patuxent Beach Road and Solomons Island Road

Location of Project:

Study to upgrade MD 4 between MD 2 and MD 235 (4.0 miles), including the Governor Thomas Johnson Memorial Bridge (Bridge 04019) over the Patuxent River and the intersection at MD 235 (2.9 miles).
Project Area Map

The purpose of the project is to improve existing capacity and traffic operations, improve vehicular, pedestrian and bicycle safety along the MD 4 study corridor, while simultaneously supporting existing and planned development. MD 4 provides commuters in the area with access to the District of Columbia (Washington, DC), and the Patuxent Naval Air Station, St. Mary's largest employer. The project area includes four road segments:

  • MD 4/MD 235 intersection in St. Mary's County;

  • Mainline MD 4 in St. Mary's County;

  • Thomas Johnson Bridge; and

  • MD 4 Mainline in Calvert County.

The Thomas Johnson Bridge portion of MD 4 is a two lane bridge that connects St. Mary's and Calvert counties over the Patuxent River. It also is an evacuation route for the Calvert Cliffs Nuclear Power Station. High traffic volumes during peak travel hours cause frequent traffic delays. Traffic often comes to a stop during bridge maintenance activities or following crashes, as bridge shoulder widths are insufficient to handle emergency and repair vehicles.

Additional information on existing and projected traffic demand, environmental, economic, demographic land use characteristics can be found by clicking on the link to the MD 4 Thomas Johnson Bridge Project Planning Study, Purpose and Need Document, May 2008.

What Is Under Study:

The Maryland State Highway Administration (SHA), secured Federal Highway Administration (FHWA) Location Approval of SHA’s “Selected Alternative” on September 10, 2015, concluding the Project Planning Phase of this Project. FHWA’s Location Approval represents a determination that SHA’s final environmental document, the “Finding of No Significant Impact” (FONSI), September 2015, adequately and accurately described the need, environmental issues, and impacts of the project and appropriate mitigations measures. It further concludes that SHA’s Selected Alternative would best address existing and projected operational needs while minimizing environmental impacts throughout the study area.

Details of the Selected Alternative were presented at an Informational Workshop held on April 15, 2015. The Selected Alternative includes improvements along four road segments along the MD 4 corridor, as described below:

  1. MD 235/MD 4 Single Point Urban Interchange (SPUI)

  2. Rendering of SPUI

    • MD 235 would be elevated over MD 4, with two lanes of free flowing traffic in each direction.

    • Ramps would be used to direct all left turns between MD 235 and MD 4 to a single signalized intersection under the bridge.

    • Properties located on northbound MD 235 would gain access to MD 235 through new service roads.

    • MD 4 would remain at its existing grade with two lanes in each direction.

    • A traffic light located on MD 4, under the MD 235 span, would control turning movements.

    • A bicycle/pedestrian path on MD 4 would connect to the county’s proposed Three Notch Trail.

    • MD 235/MD 4 Single Point Urban Interchange (SPUI) Aerial View St. Mary’s County, April 2015.

  3. MD 4 Mainline, St. Mary’s County: Four-Lane Roadway with Open Median and Separate Bicycle/Pedestrian Path

    • Typical section-zoom to view-(not to scale) Typical Section-MD 4 Mainline, St. Mary's County

    • MD 4 would be widened from two lanes to four lanes with a 30-foot-wide median.

    • The existing road would be reconstructed to carry northbound traffic.

    • Two new lanes, constructed to the north of the existing road, would carry southbound traffic.

    • A bicycle/pedestrian path would be constructed to the south side of MD 4.

    • Proposed improvements of MD 4 Mainline in St. Mary's County are shown in two separate aerial maps:

  4. Thomas Johnson Bridge- New Four-Lane Parallel Span

    • Typical section-zoom to view (not to scale) Typical Section - Thomas Johnson Bridge

    • A new four-lane parallel bridge would be built with two northbound and two southbound lanes.

    • Wide outside shoulders would accommodate disabled, emergency and repair vehicles.

    • A bicycle/pedestrian path would be located on the south side of the bridge, separated by a concrete barrier.

  5. MD 4 Mainline Calvert County - Four-Lane Roadway with Open Median

    • Typical section-zoom for detail (not to scale)

    • MD 4 would be widened into the existing open grass median to provide a four-foot-wide inside shoulder in each direction from north of the Patuxent River crossing to the MD 4/Patuxent Point Parkway intersection.

    • A new right-in/right-out access point for MD 4 northbound/Solomons Island Road would be provided at a location approximately 1,000 feet north of the closed access.

    • The remaining access points along MD 4 would not be altered.

    • Click on link to view aerial alignment of MD 4 Mainline and Thomas Johnson Bridge Improvements, Calvert County

Currently, the Thomas Johnson Bridge is funded for final design, only. Funding for design, right of way, acquisition and construction for the other project phases will proceed as funds become available.

For additional information on the planning study, visit the documents tab where you will find links to project newsletters, maps of alternatives considered during the planning study, as well as displays presented at informational workshops and the 2010 Public Hearing. Details of environmental studies are included in the August 2010 Environmental Assessment. To view details of FONSI, click on September 2015: MD 4 Project Planning Study-Finding of No Significant Impact.

Project Type:

Current Phase:Planning
Funded Year :2007 How much will this project cost?
Funding Source(s):State/Federal
Last Updated On : 12/29/2017


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