Slide One


I-495 & I-270 Managed Lanes Study

Final Environmental Impact Statement (FEIS) - Overview 

Date Published June 17, 2022

MDOT SHA and FHWA published the Final Environmental Impact Statement (FEIS) and Final Section 4(f) Evaluation for the I-495 & I-270 Managed Lanes Study (MLS), with the Notice of Availability published in the Federal Register on June 17, 2022. The FEIS provides responses to comments received on the Draft Environmental Impact Statement (DEIS) and the Supplemental DEIS as well as final traffic, engineering and environmental analyses related to the Preferred Alternative – Alternative 9 – Phase 1 South. Lastly, the FEIS details the comprehensive mitigation plan for natural, cultural, and socio-economic impacts.


The Preferred Alternative would replace the more than 60-year-old American Legion Bridge (ALB), address existing traffic and long-term traffic growth, reduce congestion, enhance trip reliability, support regional transit improvements, foster new opportunities for transit and increased carpool/vanpool/ridesharing that would help reduce reliance on single occupancy vehicles in the National Capital Region.

The FEIS also reflects successful efforts to avoid all residential and business displacements with the Preferred Alternative. On Plummers Island, a research site for the Washington Biologists Field Club, the Preferred Alternative would reduce impacts by 90% to about 0.2 of an acre by strategically locating piers for the new American Legion Bridge.

Regarding traffic benefits, the FEIS traffic analysis concludes: “The Preferred Alternative is projected to provide meaningful operational benefits to the system even though it includes no action or no improvements for a large portion of the study area to avoid and minimize environmental and property impacts. This alternative would significantly increase throughput across the ALB and on the southern section of I-270 while reducing congestion. It would also increase speeds, improve reliability, and reduce travel times and delays along the majority of I-495, I-270, and the surrounding roadway network compared to the No Build Alternative.”

Along with other new or upgraded pedestrian and bicycle improvements within the area of Phase 1 South, the Preferred Alternative would include a new shared-use path on the American Legion Bridge across the Potomac River along the east side. A direct connection of the shared-use path from the bridge to the Chesapeake and Ohio Canal towpath has been incorporated into the alternative. [FEIS, page 3-29]

On I-495, the Preferred Alternative would include two new High Occupancy Toll (HOT) managed lanes in each direction from south of the George Washington Memorial Parkway in Fairfax County, Virginia, to west of MD 187 (Old Georgetown Road) in Montgomery County, Maryland. On I-270, the Preferred Alternative would convert the existing high occupancy vehicle (HOV) lane in each direction to a HOT managed lane and add one new HOT managed lane in each direction on I-270 from I-495 to north of I-370, and on the I-270 east and west spurs. No action or no improvements would be included at this time on I-495 east of the I-270 east spur to MD 5. [FEIS Chapter 3, Preferred Alternative]

As outlined in the FEIS, the Preferred Alternative is projected to do the following:

  • Reduce system-wide delay for the entire study area by 13% during the AM peak period and by 38% during the PM peak period compared to 2045 No Build conditions. [FEIS, page 4-10]
  • Improve travel speeds and provide the option for a free flow trip in the HOT managed lanes with an average speed of 60 mph, see Table 4-6 [FEIS, page 4-12], and provide benefits to the existing lanes by improving average speeds in the general purpose lanes. Detailed corridor travel speed results by peak hour and direction for the general purpose lanes and the managed lanes are provided in Table 4-7. [FEIS, page 4-13]
  • Provide increased throughput by 2,000 vehicles per hour compared to the No Build Alternative, from an average of 15,700 vehicles per hour to an average of 17,700 vehicles across the American Legion Bridge and on I-270 north to I-370 while reducing congestion. [FEIS, page 4-15]
  • Reduce delay on surrounding local roadways, including a 4.8% reduction in daily delay on the arterials in Montgomery County, with some localized increases in arterial traffic near the managed lane access interchanges. [FEIS, page 4-16]

Some congestion would still be present during the PM peak period on I-270 northbound and the I-495 inner loop in the design year of 2045 due to downstream bottlenecks outside of the Preferred Alternative limits, and travelers on most corridors would experience significantly faster, more reliable trips.

New opportunities to support, expand transit

Beyond the travel benefits, the Preferred Alternative will create new opportunities for regional transit bus service through a reliable trip in the HOT managed lanes and would support carpooling by allowing HOV3+ vehicles and transit vehicles to travel in the HOT managed lanes toll free.

Other multimodal benefits identified in the FEIS include commitments to increase the number of bus bays at WMATA Shady Grove Metrorail Station and parking capacity at Westfield Montgomery Mall Transit Center. As part of the previously approved Phase Public-Private Partnership (P3) Agreement, the Phase Developer and MDOT SHA agreed to additional transit commitments when a Section P3 Agreement is approved by the Maryland Board of Public Works and financial close is achieved. These include an estimated $300 million for transit services in Montgomery County over the operating term of Phase 1 South. After achieving financial close of the Section P3 Agreement for Phase 1 South, MDOT would fund not less than $60 million from the Development Rights Fee, provided by the developer, for design and permitting of high priority transit investments in Montgomery County, and would deliver the Metropolitan Grove Bus O&M Facility, including the necessary bus fleet.

Research will continue at Morningstar Tabernacle No. 88 Moses Hall and Cemetery

Regarding the historic Morningstar Tabernacle No. 88 Moses Hall and Cemetery in the Cabin John area, investigation to date indicates that the Preferred Alternative avoids impacts to the Morningstar Tabernacle No. 88 Moses Hall cemetery boundary and the known and suspected burial locations. MDOT SHA and FHWA will continue to work with the Maryland Historical Trust and consulting parties and will conduct additional archaeological surveys to support an ultimate determination of the effects.

MDOT SHA and FHWA remain committed to ongoing collaboration with stakeholders and pursuing community enhancements such as improved and new pedestrian connections between the cemetery and Gibson Grove Church, context sensitive design treatment of the proposed noise barrier adjacent to the cemetery, and improved drainage compatible with and beneficial to the property. MDOT SHA will continue working with the developer to ensure protection of the cemetery property.

The Preferred Alternative avoids the area within the cemetery’s historic boundary and includes a buffer zone for additional protection. After the historical research and archaeological surveys, MDOT and FHWA have determined there is a low potential for graves within the project’s limits of disturbance outside of the cemetery’s historic boundary. Regardless, MDOT SHA and FHWA have agreed that further investigations of this area outside of the cemetery’s historic boundary are appropriate.

Publication of the FEIS is the next major milestone in a four-year NEPA process that included 16 public workshops and seven public hearings with established public comment periods. Additionally, more than 200 stakeholder, community, elected official and business meetings were held to present study information and hear concerns and feedback.

In response to public and agency comments received over the course of the Managed Lanes Study, MDOT SHA and FHWA have modified analysis methodologies, conducted new analyses, studied new or modified existing alternatives, refined design to avoid and minimize environmental and community impacts, and identified meaningful mitigation to address unavoidable impacts.

After an availability period for the FEIS, FHWA issued a Record of Decision (ROD) identifying this Study’s Selected Alternative, based on consideration of the range of reasonable alternatives, efforts to avoid and minimize impacts, and final mitigation measures designed to address potential environmental impacts. The ROD concludes the NEPA process and document the commitments to be carried forth during final design and construction.

View the FEIS Documents

FHWA and MDOT SHA have completed the Final Environmental Impact Statement (FEIS) and Draft Section 4(f) Evaluation for the Managed Lanes Study, with the Notice of Availability published in the Federal Register on June 17, 2022. The FEIS provides a summary of the 21 technical reports and contains 12 chapters.

Executive Summary also available in Amharic, Chinese, French, Korean, and Spanish.

FEIS Document by Chapter

Cover, Signature Page, Title Page, Table of Contents
Executive Summary
Chapter 1- Purpose and Need
Chapter 2- Alternatives Considered
Chapter 3- Preferred Alternative
Chapter 4- Traffic
Chapter 5- Environmental
Chapter 6- Final Section 4(f)
Chapter 7- Commitments and Mitigation
Chapter 8- Public Involvement and Agency Coordination
Chapter 9- DEIS and SDEIS Comments Responses
Chapter 10- List of Preparers
Chapter 11- Distribution List
Chapter 12- References

FEIS Technical Reports

To review the 11 supporting FEIS Technical Reports click on the report titles below.  

FEIS Appendices


Appendix A

Traffic Analysis Tech Report

Appendix B

MDOT SHA's Draft Application for IAPA (5 files)

Appendix C

Covid Monitoring Plan

Appendix D

Compensatory Stormwater Mitigation Plan

Appendix E

Environmental Resource Mapping

Appendix F

Community Effects Assessment and EJ Analysis

Appendix G

Final 4(f) Evaluation

Appendix H

Visual Impact Assessment

Appendix I

Cultural Resources Tech Report (11 files- REDACTED VERSIONS)

Appendix J

Programmatic Agreement

Appendix K

Air Quality Tech Report

Appendix L

Noise Analysis Tech Report

Appendix M

Natural Resources Tech Report (11 files)

Appendix N

Avoidance, Minimization, and Impacts Tech Report

Appendix O

Compensatory Mitigation Plan (5 files)

FEIS Appendix P


Appendix Q

Indirect and Cumulative Effects Tech Report

Appendix R

Public Involvement and Agency Coordination Tech Report

Appendix S

Agency Correspondence (# files)

Appendix T

DEIS and SDEIS Comments and Responses (13 files)

Appendix U

Environmental Assessment Form

FEIS Document Availability

Hard copies of the FEIS and supporting technical reports were are available for review in multiple locations in Montgomery and Prince George’s Counties, as well as one in Fairfax, Virginia and one in Washington, D.C. from June 17, 2022 through July 18, 2022.

Document Availability



Gaithersburg Library

18330 Montgomery Village Avenue

Gaithersburg, MD 20879


Quince Orchard Library

15831 Quince Orchard Road

Gaithersburg, MD 20878    


Rockville Memorial Library

21 Maryland Avenue

Rockville, MD 20850


Davis Library

6400 Democracy Boulevard

Bethesda, MD 20817           


Kensington Park Library

4201 Knowles Avenue

Kensington, MD 20895       


Chevy Chase Library

8005 Connecticut Avenue

Chevy Chase, MD 20815    


Silver Spring Library

900 Wayne Avenue

Silver Spring, MD 20910     


White Oak Library

11701 New Hampshire Avenue

Silver Spring, MD 20904     




Beltsville Branch

4319 Sellman Road

Beltsville, MD 20705


Greenbelt Branch

11 Crescent Road

Greenbelt, MD 20770         


New Carrollton Branch Library

7414 Riverdale Road

New Carrollton, MD 20784


Glenarden Branch Library

8724 Glenarden Parkway

Glenarden, MD 20706         


Largo-Kettering Branch Library

9601 Capital Lane

Upper Marlboro, MD 20772          


Spauldings Branch Library

5811 Old Silver Hill Road

District Heights, MD 20747


Oxon Hill Branch

6200 Oxon Hill Road

Oxon Hill, MD 20745




Dolly Madison Library

1244 Oak Ridge Avenue

McLean, VA 22101  




Juanita E. Thornton/Shepherd Park Neighborhood Library

7420 Georgia Avenue NW

Washington, DC 20012