I-95/I-695 Preliminary and Final Design
Location: Baltimore County, Maryland
Client: Maryland Transportation Authority
Aerial view of interchange
JMT led the design of improvements to several miles of I-95 as well as a complete realignment of the I-95/I-695 interchange, the first highway transportation project in Maryland to implement general purpose lanes and express toll lanes together in the same facility.
JMT was responsible for Stage I and II Project Planning engineering, environmental documentation and preparation of the FONSI for the entire Section 100 project, refining all I-95 ETL Section 100 alternatives. Subsequently, JMT was selected to provide preliminary and final design for the $450 million I-95/I-695 interchange, which was advertised in multiple contracts. Final design included 11 lane-miles of Interstate 95, 12 lane-miles of Interstate 695, 1 lane-mile of local roads and 16 lane-miles of ramps. JMT coordinated the design with adjacent developers to minimize impacts.
Highway Design: The preliminary design included developing and analyzing multiple concepts for General Purpose and Managed Lanes for I-95's mainline. In addition, JMT refined multiple line and grade options for the I-95/I-695 interchange and prepared the final design and geometrics of this complex interstate interchange. The preliminary design encompassed an array of design elements, which included horizontal and vertical alignment, typical sections, developing and reviewing design standards, and minimizing impacts to the existing ROW and utilities. One of the unique challenges was the re-design of the existing "double-braided" directional I-95/I-695 interchange to a fully directional multilevel design with no ingress or egress ramps from left lanes of the two mainlines. Complex MOT plans were prepared to stage this interchange without disrupting the existing traffic of nearly 200,000 ADT.
Traffic Forecasting and Engineering: JMT performed travel demand forecasts for the various alternatives, conducted travel time runs and performed traffic counts. In addition, JMT performed capacity and operational analyses, studied MOT options and evaluated constructability issues and evaluated impacts to signing, lighting and ITS systems.
Structural Engineering: JMT prepared preliminary layouts of bridge structures in a complex network of multilevel interchange design at the I-95/I-695 interchange involving many elevated structures for the directional ramps. The preliminary structural design work included superstructure types, span arrangements, pier locations and sizes and phased construction. JMT is prepared final design for 22 bridges, 30 retaining walls, 6 noise barriers and 5 culverts at the I-95/I-695 interchange.
Geotechnical Engineering: More than 290 borings were required to satisfy the project requirements. Our geotechnical investigations and evaluations culminated in the development of a geotechnical report of findings and recommendations for bridge foundations, retaining walls, noise walls, pavement design, slope stability, storm water management ponds, and utility directional drilling.
Additional Services: Preliminary and final design included wetland and forest delineation, coordination with environmental agencies (MDE, USACOE, MHT etc.), permitting requirements, drainage and stormwater management, utility coordination and relocations, hydrology/hydraulics analyses and extensive public involvement and interagency coordination. JMT utilized focus group meetings with agencies and communities to establish the Purpose and Need, ARDS document and FONSI. Brochures, displays and material for the I-95 Section 100 web page were prepared.
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