Environmental

I-495 & I-270 Managed Lanes Study

I-495 & I-270 Managed Lanes Study

I-495 & I-270 Managed Lanes Study

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Alternatives Retained for Detailed Study

Following the completion of additional traffic, financial and environmental analysis in Winter 2019, MDOT SHA recommended that six of the Screened Alternatives, which included five build alternatives and the no build, presented at the Spring 2019 Public Workshops be carried forward as the Alternatives Retained for Detailed Study (ARDS).

Click each alternative in the chart below to view artistic renderings and descriptions that show how the alternative could work.

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Other Alternatives Considered

Since the Spring 2019 Public Workshops, based on the Federal Highway Administration’s continued review of the traffic analysis completed for the Screened Alternatives and in review of new financial information, Alternative 5 was not considered a reasonable alternative to be retained for detailed study. Results of the traffic analysis showed that Alternative 5 would perform the worst of the Screened Alternatives for most metrics used to evaluate existing traffic and long-term traffic growth and trip reliability, and would perform the worst among the Screened Alternatives in system-wide delay, corridor travel time, density/level of service and travel time (for general purpose lanes). However, Alternative 5 is included in the DEIS for comparison purposes.

After the Spring 2019 Public Workshops, an additional alternative, the MD 200 (Intercounty Connector (ICC)) Diversion Alternative was also evaluated at the suggestion of Montgomery County officials and other agency stakeholders, which considered elements of the Montgomery County Regional Transportation Improvement Plan. The alternative proposed an alternate route for travelers to use MD 200 (ICC) instead of the top side of I-495 between I-270 and I-95 to avoid or reduce impacts to significant, regulated resources and residential relocations. The MD 200 (ICC) Diversion Alternative assumed no widening or new capacity on the top side of I-495 between I-270 and I-95, but did consider other potential less-impactful improvement options (known as Transportation System Management/Transportation Demand Management, or TSM/TDM, options), such as ramp metering and hard shoulder running, to attempt to relieve congestion.

MDOT SHA’s evaluation of the MD 200 (ICC) Diversion Alternative indicated that it would not meet the Study’s Purpose and Need of accommodating long-term traffic growth or enhancing trip reliability. The proposed TSM/TDM solutions on the top side of I-495 were either geometrically infeasible or would not provide substantial relief to accommodate long-term traffic needs. Also, the analysis indicated that MD 200 would not have sufficient spare capacity in the design year (2040) to draw enough traffic off I-495 to reduce congestion. As a result, the MD 200 (ICC) Diversion alternative would be projected to perform worse than all other Screened Alternatives in several key traffic metrics, including delay per vehicle, average speed in the general-purpose lanes, and level of service. On the top side of I-495 between I-270 and I-95, the MD 200 (ICC) Diversion Alternative is projected to perform worse than the no build. Therefore, the MD 200 (ICC) Diversion alternative was not carried forward. MDOT SHA will continue to work with our environmental agency partners to minimize impacts as much as possible on the remaining alternatives that meet the purpose and need.