The I-270 Watkins Mill Road Interchange in the heavily congested Washington, D.C., region united two separated parts of the Gaithersburg City, increasing economic opportunity, improving community access to a major hospital and relieving congestion. The $124 million project is one of the largest new interchange projects designed and built in recent Maryland history. Construction included a new interchange on I-270 consisting of 14 structures, including a new five-span bridge spanning I-270 and the Tributary to Seneca Creek. Besides trying to minimize right-of-way needs, major design concerns included balancing/minimizing the impacts to a stream relocation along the entire southbound portion of I-270 and providing room for a future I-270 widening/High Occupancy Vehicle lane project. Now complete, the interchange provides another critical link to I-270, spurring economic growth for Montgomery County and Gaithersburg City, decreasing traffic congestion, and improving the quality of life for residents.