route ascends onto the Francis Scott Key Bridge, which carries I-695 over the lower Baltimore Harbor and Patapsco River. Unlike the Fort McHenry or Baltimore Harbor tunnels, hazmat trucks are allowed to cross the Francis Scott Key Bridge. After crossing the Patapsco River over the bridge the route touches down within the Baltimore city limits and continues west past Thoms Cove through Hawkins Point's industrial areas. It comes to an interchange with Quarantine Road, which provides access to MD 173, south of Curtis Bay. By this point, the route's signage changes from north–south to east–west. Past this interchange, the Baltimore Beltway continues west and returns to the Curtis Creek drawbridges. Exit numbering As opposed to I-495 (Capital Beltway) around Washington DC, on which exit numbers are generally arranged by mileposts counterclockwise starting at the southern crossing of the Potomac River, the exit numbers for the Baltimore Beltway are arranged consecutively clockwise starting at interchange 1 at Quarantine Road, west of the Francis Scott Key Bridge crossing of the Patapsco River. History The Baltimore County Planning Commission first conceived the Baltimore Beltway as a county-level roadway project in 1949; by 1953, the project was taken over by the state due to slow progress at the county level. The project was included as part of the Interstate Highway System by 1956, increasing the speed of construction due to federal funds available. The first part of the Baltimore Beltway to be completed was in December 1955 between MD 25 (Falls Road) and the Harrisburg Expressway (present-day I-83). In 1956, the next portion of the road between the Harrisburg Expressway and MD 45 (York Road) opened. Several more segments of the Baltimore Beltway would be built in the following years, with the section from MD 168 (Nursery Road) to the Glen Burnie Bypass (present-day I-97) opening in 1957; the portions from MD 45 to MD 542 (Loch Raven Boulevard), MD 7 (Old Philadelphia Road) to US 40 (Pulaski Highway), and from MD 168 to US 40 (Baltimore National Pike) opening in 1958; the segment from MD 2 (Ritchie Highway) to the Glen Burnie Bypass completed in 1960; the portion from US 1 (Belair Road) to MD 7 finished in 1961; and the portions from MD 542 to US 1 and from US 40 to MD 25 finished in 1962. At this time, the original length of the Baltimore Beltway, from MD 2 in the