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Midcounty Corridor Study


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  1. March 2015 Draft Preferred Alternative/Conceptual Mitigation Report (PA/CM)
  2. MCDOT February 4, 2014 Responses to Comments from USACE/MDE/EPA/the City of Gaithersburg
  3. MDE December 12, 2013 Information Request Letter
  4. Planning Board November 25, 2013 Recommendation Letter
  5. USACE November 19, 2013 Information Request Letter
  6. EPA August 20, 2013 Comment Letter
  7. Transcript for August 7, 2013 USACE/MDE Joint Public Hearing
  8. Public Notice for August 7, 2013 USACE/MDE Joint Public Hearing
  9. The City of Gaithersburg July 17, 2013 Comment Letter
  10. May 2013 Draft Environmental Effects Report (EER)
  11. June 2012 Midcounty Corridor Study Video
  12. June 2012 Midcounty Corridor Study Traffic Report
  13. November 2010 Alternative Retained for Detailed Study (ARDS) Map
  14. November 2010 Modified ARDS Recommendations
  15. June 2010 ARDS Recommendations
  16. January 2007 Purpose and Need
  17. Contact Us/Comments


Project Overview

Project Background
Project Team
Project Area Map
Project Schedule and Process
Purpose and Need

This project provides for Facility Planning, Phase I and preparation of an environmental document to evaluate alternatives providing congestion relief and improving vehicular, pedestrian, and bicycle mobility for the corridor east of I-270, more specifically between existing Midcounty Highway and future Snowden Farm Parkway (A-305) at MD 27. The study will also evaluate widening Middlebrook Road east of MD 355.

Project Background

Since the 1960s, Midcounty Highway has been an element of the transportation master plan for Montgomery County. Over the years, the County has built and opened to traffic the segment of Midcounty Highway from Shady Grove Road to Montgomery Village Avenue. As well, the extension north toward Clarksburg has undergone planning and right-of-way has been dedicated for portions of the master plan alignment.

In December 2003, the Montgomery County Department of Transportation (MCDOT) began a planning study as the first step toward evaluating the need and feasibility for the remainder of the Midcounty Highway master plan alignment. As part of the planning process, the County determined the purpose and need for the extension of Midcounty Highway and examined the environmental features in the master plan alignment corridor. These findings and the proposed purpose and need were presented at a public workshop in November 2004.

Following the public workshop, concerns were raised by state and federal environmental resource agencies that the purpose and need for the Midcounty Highway extension should be further defined. The agencies also requested other alternatives be evaluated in addition to the master plan alignment.

Accordingly, the MCDOT has invested additional resources to provide greater analysis, and the result of the new direction is the broader Midcounty Corridor Study (MCS). The Midcounty Corridor Study expands the scope to a larger region and evaluates more alternatives with different alignments and with traffic improvement measures for the corridor east of I-270 between Clarksburg and Gaithersburg.

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Project Team

Sponsoring Agency
Montgomery County Department of Transportation (MCDOT)
Lead Concurring Agency
US Army Corps of Engineers (USACE)
Concurring Agencies
US Environmental Protection Agency (USEPA)
Maryland Department of the Environment (MDE)
Reviewing Agencies
US Fish and Wildlife Service (USFWS)
Maryland Historical Trust (MHT)
Maryland Department of Natural Resources (MDNR)
Maryland-National Capital Park and Planning Commission (M-NCPPC)
Montgomery County Department of Permitting Services (MCDPS)
Maryland State Highway Administration (MSHA)
City of Gaithersburg

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Project Area Map

Project Area Map

Please click on the image above to zoom, pan, and reset map.


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Project Schedule and Description of Process

January 2004 Midcounty Highway, Facility Planning Phase I commences
November 2004 Public Workshop #1, Midcounty Highway Purpose and Need presented
April 2006 The Midcounty Highway is expanded to reflect a broader project called the Midcounty Corridor Study (MCS) and is required to follow the National Environmental Policy Act (NEPA) process
January 2007 Midcounty Corridor Study Purpose and Need approved
December 2007 Public Workshop #2, 11 Preliminary Alternatives presented
February 2011 Alternatives (6) Retained for Detailed Study (ARDS) approved

June 2012

Public Workshop #3, Detailed Studies presented

May 2013

Publish Draft Environmental Effects Report (EER) and submit Joint USACE/MDE Permit Application

August 2013

USACE/MDE Joint Public Hearing on Draft EER and Permit Application

February 7, 2014
We are here!

Respond to the USACE and MDE Information Request Letters

Summer 2014

Submit Preferred Alternative and Conceptual Mitigation (PACM) Report

Summer 2014

USACE/EPA/MDE concur with PACM

Fall 2014

Submit Final EER and Mitigation Plan

Winter 2014/2015

USACE completes Environmental Assessment (EA)

Winter 2014/2015
USACE renders Permit Decision (NEPA Process Complete)
Midcounty Corridor Study (MCS) concludes.

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Purpose and Need

The MCDOT is performing the Midcounty Corridor Study to: relieve projected congestion on roadways between Gaithersburg and Clarksburg; improve mobility east of I-270; improve safety and efficiency; improve vehicular, pedestrian, and bicycle access to destinations within the study area; and to develop these improvements in an environmental sensitive manner. 

The identified needs for the project are based on current and projected traffic congestion and accident history.  The needs for the project include:

  • Reduce Existing and Future Congestion.  Several intersections along MD 355 and other major roadways in the study area are operating at unacceptable levels of service now.  Almost every signalized intersection will worsen over the existing condition, and in many cases, will deteriorate beyond the County’s acceptable threshold by 2030.  North-south travel times along the existing arterials will also significantly increase in the future.
  • Improve Vehicular Safety.  The accident history of MD 355 exceeds the statewide average for similar roadways.  Most of the accidents are clustered around the numerous intersections on MD 355.
  • Enhance the Efficiency of the Roadway Network and Improve the Connections Between Economic Centers.  Currently, localized north-south travel is provided by MD 355, which has little to no access control with numerous intersections and driveways.  In fact, between MD 124 and MD 27 there are almost 100 access points along MD 355 over a distance of 4.3 miles.  Improved network efficiency and connections between the economic and residential centers in the study area are necessary to facilitate the movement of goods and people in the region.
  • Accommodate Planned Land Use and Future Growth.  This region of the county is among the fastest growing for both employment and housing, with a sizable portion of the county’s remaining residential growth planned within the study area.
  • Provide Bicycle and Pedestrian Connections.  The region lacks adequate north-south, off-street bike paths necessary to provide continuity and connections between existing and future bike facilities in the region.
  • Enhance Emergency Response.   Improved north-south access would enhance emergency response and evacuation by providing an efficient alternative to the existing congested north-south routes.  Furthermore, less congestion on the existing routes would improve emergency response along these roadways.

Purpose and Need Statement - January 2007 (pdf, 11.3mb)
US Army Corps of Engineers Concurrence (pdf, 69kb)
Maryland Department of the Environment Concurrence (pdf, 948kb)
US Environmental Protection Agency Concurrence (pdf, 71kb)

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