the north end of the turnpike and the south end of the Maine Turnpike in Kittery, was an expressway with partial grade separation that did not meet Interstate Highway standards. Its crossing over the Piscataqua River, the Maine–New Hampshire Interstate Bridge, was also a movable lift bridge that caused delays for motorists, especially during busy holiday weekends. A high-level, six-lane bridge over the Piscataqua River, connecting with extensions of I-95 through Portsmouth and Kittery, was proposed in the early 1960s to complete the missing link in the freeway. A competing plan to twin the existing Maine–New Hampshire Interstate Bridge was submitted by the Maine government, but was determined to be more costly due to land required for its approaches, which were already occupied by buildings. Following a four-year debate, the New Hampshire state legislature approved designs for the high-level bridge in early 1965 despite some opposition from Portsmouth residents. A concurrent bill had been passed by Maine in 1963 but rejected by New Hampshire. Construction of the Piscataqua River Bridge began in February 1968 and cost $50 million (equivalent to $ in ). It opened on November 1, 1972, completing the missing link between the sections of I-95 in New Hampshire and Maine. The project also included an expanded interchange with the Spaulding Turnpike, allowing traffic to bypass the Portsmouth Traffic Circle, and a new interchange at Market Street in an area marked for urban renewal. On June 24, 1970, four construction workers on the bridge fell to their deaths when a platform gave way on the Maine approach. Later history Traffic volumes on the turnpike grew to an average of over 12,700 vehicles per day by 1962, prompting state officials to propose an expansion. Plans for the new Piscataqua River Bridge had already included a wider approach, while the south end at the Massachusetts state line was constructed as an eight-lane highway in 1968. A 1969 report to the state legislature recommended the addition of four lanes to the existing turnpike and reconstruction of the Hampton toll plaza at a cost of $3 million (equivalent to $ in ). The widening of the New Hampshire Turnpike to eight lanes began in early 1973 and required the acquisition of 271 properties and the rebuilding of several bridges. During construction, several major holiday backups—some as long as —plagued the turnpike. The Hampton toll plaza was relocated north and expanded in February