Baltimore’s Corman Construction Inc. is gaining first-hand experience in creating an urban diamond interchange at Interstate 695 and MD 140 in Baltimore County. Although new to this particular area, this type of interchange has been used in more than 20 states to manage heavy traffic since the 1970s.
An urban diamond requires only one traffic signal system to control the entire interchange, which helps to accommodate more vehicles and eliminate delays. Vehicles making left turns pass opposing traffic on the driver’s right side, so the two vehicles’ paths do not intersect.
According to the Maryland State Highway Administration (SHA), the work order calls for the replacement of the existing MD 140 (Reistertown Road) bridge over I-695 (Baltimore Beltway) and reconstruction of the interchange. Located northwest of Baltimore, the interchange provides access between one of the major arteries and the interstate roadway system in Baltimore County.
The SHA noted, “The mandate to maintain a safe and efficient highway system has driven the need for improvements at this interchange.” Traffic congestion is increasing yearly, and is expected to grow by nearly 40 percent by 2020. Over the next 20 years, projections are for an additional 15,000 daily vehicle trips on MD 140 and 52,000 daily vehicle trips on I-695.
The existing four-span bridge at the interchange was built in 1961 (measuring 232 ft. (70.7 m.) long and 82 ft. (24.9 m) wide). It has not been widened or rebuilt since. It will be removed in sections and replaced with a new 185-ft. (56.3 m.) long two-span bridge to meet the I-695/MD 140 interchange ramps. The new bridge will be 202-ft. (61.5 m.) wide at the southern end, 148-ft. (45.1 m) wide at the center pier, and 202 ft. (61.5 m.) wide at the northern end. It will accommodate four lanes, two center left-turn lanes and two 5-ft. (1.5 m) sidewalks. It also will be raised slightly higher to provide vertical clearance for future I-695 widening and bring the clearance up to current interstate highway standards. The bridge will include decorative parapet walls with black iron railings and accent lighting. In addition, four of the existing interchange ramps will be reconstructed and widened.
Although the number of through lanes on MD 140 will remain the same with two in both directions, the number of left turn lanes will be increased to provide two lanes in both directions. A third northbound lane will also be added on MD 140.
The two-year contract was awarded to Corman Construction for $13.7 million. According to Gradon Tobery, assistant district engineer for the SHA’s construction section for Baltimore and Harford Counties, 90 percent of funding comes from the Federal Highway Administration and 10 percent comes from the SHA.
Notice to proceed was given on Oct. 16, 2000, and the scheduled completion date is set at Dec. 15, 2002. Carlos Cisneros, Corman’s senior project engineer, reported that the job is approximately 40 percent complete and is running right on schedule. He noted that one of the biggest challenges for the crew is that full traffic must be maintained throughout the entire project.
According to Tobery, another challenge is being able to move the proper equipment in to work. He said, “It’s a tight area, so we can’t use large equipment like huge cranes. We need to use smaller equipment and handle the job in smaller pieces.” The total job site covers about 1 mi. (1.6 km).
Cisneros reported that the number of employees assigned to the job fluctuates between 25 and 50. The majority of the equipment in use is owned by Corman, but approximately 20 percent of it is rented. Key elements include two Grove cranes: an RT 750 and an RT 760, a Liebherr 914 rubber tire backhoe, two Komatsu PC 150 backhoes, a Cat IT28 front-end loader, a Bomag BW213 compactor (smooth drum roller), a Cat 815 sheep’s foot rover, two 60-ft. (18.2 m) Grove manlifts, a Bobcat skid steer loader, a Bobcat mini-excavator, a John Deere 450 track dozer and a John Deere 450 track loader.
Major subcontractors include Rommel Electric, Odenton, MD; Aggregate Industries, Greenbelt, MD; and High Steel, Lancaster, PA.
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