King's Highway 412, or simply Highway 412, is a tolled controlled-access highway in the Canadian province of Ontario. The route is approximately 10 km (6.2 mi) long, connecting Highway 401 with the eastern extension of Highway 407. The route lies entirely within Whitby in the Regional Municipality of Durham, travelling within one kilometre of the border between Whitby and Ajax and Pickering (Lake Ridge Road).
During planning, the route was known as the West Durham Link. Its designation as Highway 412, the first new 400-series designation in several decades, was confirmed along with Highway 418 on February 6, 2015. Although initially planned to open in October 2015, the opening was delayed until June 20, 2016. Highway 412 opened alongside the extension of Highway 407 (Highway 407E) from Brock Road in Pickering to Harmony Road in Oshawa. The Ministry of Transportation of Ontario (MTO) thus decided to compensate for delays by waiving all tolls until February 1, 2017.
Highway 412 is a 10-kilometre (6.2 mi) four-lane tollway extending from Highway 401 to Highway 407E, just north of Highway 7. The entire length of the route lies between Lakeridge Road and Coronation Road, within Whitby. At the southern end, the route begins at a three-level stack interchange with a realigned Highway 401, from which it proceeds north. It crosses Dundas Street (former Highway 2), where a partial interchange provides access to the north and from the south.
North of Dundas Street, the route swerves westward onto the alignment of Halls Road and crosses Rossland Road; a future interchange is planned at this location. It continues north to an interchange with Taunton Road before diverging east from the Halls Road alignment to travel parallel between it and Coronation Road. The route crosses Highway 7 (Winchester Road), where a partial interchange provides southbound access and a northbound exit; a commuter carpool parking lot lay on the northwest corner. Immediately north of Highway 7, the route ends at a three-level stack interchange with Highway 407E, which is also a toll route thus no ETC cameras are present there.
The West Durham Link, as it was then known, was first presented to Whitby Council on February 10, 1992. It quickly drew the ire of local residents fearful of noise levels and the environmental effects on Lynde Creek. However, the recession of the mid-1990s resulted in Highway 407 being truncated in Markham temporarily. Slightly revised plans for the links appeared on the June 2007 Technically Recommended Route Report for the extension of Highway 407 to Highway 35/115, which was submitted as part of the environmental assessment (EA) for the extension, but had been announced earlier that year on March 7 by the Government of Canada, as part of an investment in Greater Toronto Area infrastructure.