In 2011, construction began on a westward extension called the Right Honourable Herb Gray Parkway.
This new route follows, but does not replace, former Highway 3 between the former end of the freeway and the E. Row Expressway, at which point it turns and parallels that route towards the site of the future Gordie Howe International Bridge.
This system primarily serves to accommodate and organize various traffic movements from the Highway 403 / 410 and Highway 427 interchanges along Highway 401, replacing an earlier plan that would have run Highway 403 directly to Eglinton Avenue and the never-built Richview Expressway.
East of the interchange with Renforth Drive, the collector lanes diverge to become the on-ramps to Highway 427 northbound and southbound.
The second 43.7 km (27.2 mi) system passes through the centre of Toronto and ends in Pickering to the east.
Progressing eastward, eight lanes are carried beneath the large spaghetti junction at Highway 427.
Access between the two is provided by transfers, which are strategically placed to prevent disruptions caused by closely spaced interchanges.
It returns to its eastward route through Toronto, now carrying 12–16 lanes of traffic on four carriageways.In addition, Highway 401 was equipped with a traffic camera system called COMPASS in early 1991.Using closed-circuit television cameras, vehicle detection loops and LED changeable-message signs, COMPASS enables the MTO Traffic Operations Centre to obtain a real-time assessment of traffic conditions and alert drivers of collisions, congestion and construction.The speed limit is 100 km/h (62 mph) throughout its length, with the only exceptions being the posted 80 km/h (50 mph) limit westbound in Windsor and in most construction zones.By the end of 1952, three individual highways were numbered "Highway 401": the partially completed Toronto Bypass between Weston Road and Highway 11 (Yonge Street); Highway 2A between West Hill and Newcastle; and the Scenic Highway between Gananoque and Brockville, now known as the Thousand Islands Parkway.