S. George Mason Dr. & S. Four Mile Run Dr. Intersection Study

Final Report and Video Update Available

Learn more about the conclusions of study and what comes next for this key intersection with our short video update:

Learn More!

Status

Complete

The study is complete and the project team has released a short video with an explanation of what we learned about this key intersection in Southern Arlington, and how we'll address the issues moving forward

Location

This study will advance the two preliminary design concepts for the intersection of S. Four Mile Run Drive, S. George Mason Drive, and the Washington & Old Dominion Trail. It includes the fundamental analysis for both options and includes additional review of what is necessary to grade-separate the W&OD trail from the intersection.

About theStudy

This feasibility analysis launched in partnership with the Metropolitan Washington Council of Governments (MWCOG) Regional Roadway Safety in Winter 2024/5.

The project team explored the feasibility of the intersection treatments proposed in the South George Mason Drive Multimodal Transportation Study:  a conventional intersection, a peanut-shaped roundabout, or "Peanutabout", and a grade separated W&OD trail.

• A peanutabout incorporates design features and operations of a typical roundabout. They are often used to help manage vehicle speeds and reduce the number of conflict points between motorists, trail users, bicyclists and pedestrians.

The feasibility study focused on evaluating alternatives based on improvements to traffic operations and the safety of people walking, biking, taking transit, and driving at and through the intersection.

Study Goals

• Document existing conditions
• Determine the feasibility of a peanutabout style intersection
• Determine the feasibility of a grade separated W&OD trail
• Identify preferred intersection concept using results of existing conditions, safety and traffic operations analyses 

 

Public Process

Spring 2026 - Study Results and Next Steps

Following the technical analysis and a thorough review, the project team has finalized the Study Report and identified a preferred concept for this intersection. Based on the findings of this study, the conventional signalized intersection alternative should be advanced for preliminary engineering. It also concluded that a grade separated crossing for the W&OD Trail would make meaningful safety improvements, but would require additional study to determine feasibility and cost.

Read the full report(PDF, 2MB)

The project team has prepared a video to share the results of the study in both English and Spanish.

Watch in English   |   Watch in Spanish

 

Summer 2025 - Project Introduction

Project manager Brian Shelton introduces the study and walks you through what we are looking at for this challenging intersection in a project introduction video, which covered how we're using the recommendations from the South George Mason Drive Multimodal Transportation Study, and what our next steps will be at the end of the study process.

Watch in English  |  Watch in Spanish

Topics include:

• An improved signalized intersection
• A peanutabout
  • A peanutabout incorporates design features and operations of a typical roundabout. They are often used to help manage vehicle speeds and reduce the number of conflict points between motorists, trail users, bicyclists and pedestrians.
• A grade separated W&OD trail

Funding

This feasibility study was funded by a competitive grant awarded to the county from the Metropolitan Washington Council of Governments (MWCOG) Regional Roadway Safety Program

• Learn more about the MWCOG Regional Roadway Safety Program

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