American Scientist

Many a person who has driven through the Middle Atlantic states on Interstate 95 has dreaded the approach to Washington, D.C., where traffic often slows to a crawl, if not to a complete stop. Heading north through Virginia toward Maryland, I-95 widens from two to three, and then to four and five lanes and more, to accommodate the increased traffic volume and interchange complexity as one nears the capital. About 12 miles south of Washington, traffic invariably becomes more erratic and frenetic, as cars and trucks jockey for position in anticipation of the branching of the highway into I-395 and I-495, the former going through Arlington into the District of Columbia proper and the latter being the Outer Loop of the Capital Beltway, which bypasses Washington—but not its traffic. The westward leg of I-495 carries traffic headed for Fairfax, Virginia, and Bethesda and Rockville, Maryland. Those traveling I-95 north to Baltimore and on to Philadelphia and New York generally continue on I-95, which coincides with the eastward leg of I-495.