Reconstructing an interchange is often a daunting task requiring a delicate balance of construction phasing to reduce traffic impacts and create a safe driving and working environment. Building an interchange on the site of a major intersection demands an even more intricate solution. KCI worked with the Maryland Transportation Authority (MDTA) to tackle both challenges at the same time and within close proximity by upgrading the existing I-95 interchange at MD Route 24 and replacing the MD Route 24/MD Route 924 intersection with a full grade-separated urban diamond, all within a one-half mile stretch of roadway.
Capacity and safety had become major concerns for I-95 in Harford County, Md., specifically at MD Route 24 where evening rush-hour traffic routinely slowed and backed up onto the interstate. In addition to being among the busiest interchanges north of the Baltimore Beltway, the junction provides access to a major shopping hub as well as Aberdeen Proving Ground, which has experienced an influx of new jobs and families through the Base Realignment and Closure (BRAC) process.
To eliminate congestion and backups onto I-95, traffic needed to flow freely along MD Route 24 and through the MD Route 924 intersection. We also needed to accommodate capacity at least 25 years into the future, so we looked at building a grade-separation over the intersection, along with supporting improvements to the existing I-95 interchange at MD Route 24.
Stephen F. Drumm, PEVice President, Regional Practice Leader
Plans were prepared and advertised for bid, but before a contract was signed, the Authority wanted to take a second look at the proposed dual interchanges to incorporate future plans for a major widening along I-95, called Section 200, part of the agency’s multi-year and multi-billion Express Toll Lanes initiative. “There were opportunities to optimize the design in order to minimize the amount of rework that would be required for the ultimate Section 200 construction,” said Douglas M. Hutcheson, PE, MDTA’s Chief Engineer.
KCI’s engineers went back to the drawing board to increase compatibility with future widening and reduce construction costs while still meeting the original safety and capacity goals. “We had to analyze and remodel all of the traffic flow to address exit volumes from the interstate and minimize congestion through the new grade separation,” said KCI Vice President Stephen F. Drumm, PE. “The short distance between the interchanges, high volumes and major shopping destinations made separating local and through traffic along MD Route 24 among the most critical of challenges.” Design staff brainstormed short-term, flexible alternatives that were compatible with future improvements, improved operations, and maximized the existing roadway and bridge assets.
“It was a difficult project from both the design and construction side,” said Hutcheson. “Building a full interchange to replace the busiest intersection in the county was a major endeavor.” Partnering between engineers, agencies and contractors, along with complex maintenance of traffic phasing, helped the more than 100,000 motorists that use the roadways successfully navigate the sites through several holiday seasons.
With construction complete and open to traffic, the project has met all of its goals. “We are remarkably safer on both I-95 and at MD Route 24/MD Route 924,” said Hutcheson. “We have increased capacity for now and the foreseeable future to handle the influx of people coming to the region for BRAC and other reasons.” Even though the Section 200 project is indefinitely on hold to make room for more pressing system preservation improvements, KCI’s innovative interim solution bought near-term years of service at a nearly $25 million cost savings and a significantly reduced construction timeframe, but will still be compatible with future improvements when funded.