Highway 115 begins at a trumpet interchange with Highway 401, and is concurrent with Highway 35 for to Enterprise Hill. For the length of this concurrency, it is a divided four lane RIRO expressway. Here, Highway 35/115 meets the eastern terminus of Highway 407 at a modified trumpet interchange in Clarington, and at Enterprise Hill, the expressway curves eastward and Highway 35 exits, continuing north towards Lindsay. Highway 115 continues northeast, and the two carriageways diverge, making it a freeway. A depressed grass median, generally wide, separates the opposing directions of travel between this point and Peterborough. Most of the remainder of the highway is straight and surrounded by agricultural lands and forests, until it meets Highway 7. From this point northeastward, Highway 115 is part of the southern Ontario route of the Trans-Canada Highway and concurrent with Highway 7. The freeway continues along the southern edge of Peterborough and ends at Lansdowne Street to the east of the city. Highway 7 continues east towards Ottawa.
History
Highway 115 was a new highway constructed in the mid-1950s and gradually improved over the following 40 years. Initially, the route was constructed as a two lane connection from Highway 35 near Pontypool to Highway 28 on the outskirts of Peterborough. Because of this, it was known as the Pontypool–Peterborough Road. It was eventually extended to Highway 7 on the east side of Peterborough and later widened to a four-lane expressway in the late 1980s. Since then, improvements have been proposed to extend Highway 115 east to Highway 28, but none have come to fruition. In 1953, construction began on a two lane road northeastward from Highway 35 south of Pontypool, with the purpose of creating a shorter route between Toronto and Peterborough. The Pontypool–Peterborough Road, as it was referred to during construction, was completed and designated as Highway 115 on March 17, 1955, ending at an intersection with Highway 28 which became notoriously dangerous. In 1961, Highway 115 was extended southward to the 401, becoming concurrent with Highway 35. That same year, the new Peterborough By-pass opened, providing a route for Highway 7 around the south side of the city via Monaghan Parkway. Highway 115 was later extended east to connect with the bypass, and the northern terminus became the intersection of Erskine Avenue and Lansdowne Street. The extension was opened at a ribbon-cutting ceremony on August 25, 1978. The entire length of the highway south of Highway 7 was widened to four lanes in the 1980s and early 1990s. Later, Highway 115 was rerouted to join Highway 7 on the newly four-laned Peterborough By-pass route. Although Highway 115 currently meets many Ontario freeway design standards northeast of the Highway 35 interchange, there are currently no plans to re-designate this section as a 400-series highway. Consequentially, the codesignation with the Highway 35 RIRO expressway could also be dropped, thus finally eliminating the designation of "Highway 115" entirely.
