Template:Infobox Ontario road

King's Highway 401, also known by its official name as the Macdonald–Cartier Freeway and colloquially as the four-oh-one,^[1] is a 400-Series Highway in the Canadian province of Ontario stretching from Windsor to the Quebec border. The segment of Highway 401 passing through Toronto is the busiest road in North America,^[2] and one of the widest and busiest in the world.^[3][4] Together with Quebec Autoroute 20, it forms the transportation backbone of the Quebec City – Windsor Corridor, along which over half of Canada's population resides. The entire route is maintained by the Ministry of Transportation of Ontario (MTO) and patrolled by the Ontario Provincial Police. The posted speed limit is 100 km/h (62 mph) throughout its length.

Three highways were renumbered "Highway 401" in 1952: the 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. These three sections of highway were 11.8 km (7.3 mi), 54.7 km (34.0 mi) and 41.2 km (25.6 mi) long, respectively, at the time of their assumption.

It became fully navigable from Windsor to the Quebec border in 1964. In 1965, the highway was given a second designation, the Macdonald–Cartier Freeway, in honour of the fathers of Confederation. By the end of 1968, the Gananoque–Brockville section was bypassed and the final intersection grade-separated near Kingston, making Highway 401 a freeway for its entire 815 km (506 mi). On August 24, 2007, the portion of the highway between Trenton and the Don Valley Parkway in Toronto was designated the Highway of Heroes, as the road is travelled by fallen Canadian servicemen and women from the Canadian Forces Base to the coroner's office in Toronto.

Highway 401 extends across Southwestern, Central and Eastern Ontario. In foresight of the future expansion of the highway, the planners purchased a 91.4 m (300 ft) right-of-way along the entire length. Generally the highway occupies only a portion of this allotment.^[5] The 401 is one of the world's busiest highways;^[3] a 2006 report stated that the annual average daily traffic (AADT) count between Weston Road and Highway 400 in Toronto was estimated at 431,900,^[6] with up to 500,000 vehicles passing over it on some days.^[2] This makes it the busiest roadway in North America, surpassing the Santa Monica Freeway in Los Angeles, Interstate 10 (I-10) in Houston and I-75 in Atlanta.^[7] The just-in-time auto parts delivery systems of the highly integrated auto industry of Michigan and Ontario have contributed to the highway's status as the busiest truck route in the world,^[8] carrying 60% of vehicular trade between Canada and the US.^[7]

Highway 401 also features the busiest multi-structure bridge in North America, located at Hogg's Hollow in Toronto.^[8] The four bridges, two for each direction with the collector and express lanes, carried an average of 373,700 vehicles daily in 2006.^[6] The 401 is one of the major backbones of a series of highways in the Great Lakes region, connecting the populous Quebec City – Windsor corridor with Michigan, New York, and central Ontario's cottage country.^[9] It is the principal connection between Toronto and Montreal, becoming Autoroute 20 at the Quebec border.^[10]

The border crossing between Windsor and Detroit is the busiest trade crossing in the world.^[8] However the 401 itself does not physically extend the last few kilometres to Detroit.^{[note 1][11]} A proposed Windsor–Detroit border crossing may result in Highway 401 connecting directly to the border as early as 2013.^[12] At present, Highway 401 begins at Huron Church Road (formerly Highway 3) in Windsor,^[13] with four lanes diverging north and leaving Talbot Road (Highway 3) at Howard Avenue. At Dougall Avenue, the highway veers east, widens to six lanes and exits Windsor.^[14] From here, the 401 mostly parallels the former route of Highway 98 from Windsor to Tilbury.^[13] From Tilbury, the highway loses its tall wall median barrier and narrows to four lanes, following lot lines laid between concession roads in a plan designed to limit damage to the sensitive agricultural lands through which the highway runs.^[15] Due to fatigue caused by the lack of driver engagement along the flat and straight lengths of highway,^[16] the section of the 401 from Windsor to London (especially west of Tilbury) has become known for deadly car accidents and pile-ups, earning it the nickname Carnage Alley.^[17] As the highway approaches London, it partially interchanges with Highway 402^[14] and widens back to six lanes.^[18] Within London, the 401 intersects the city's two municipal expressways, Highbury Avenue and the Veterans Memorial Parkway.^[19]

The section between London and Woodstock generally parallels the former Highway 2 but lies on the south side of the Thames River.^[14] While the topography in this area is less flat, the highway remains generally straight. To the south of Woodstock, Highway 401 curves northeast and partially interchanges with Highway 403. ^[19] The 401 then winds towards Kitchener and Cambridge, where it encounters Highway 8 and returns to its eastward orientation.^[14][20] Some sections of the Highway 401 between Woodstock and Kitchener are four lanes, but these are currently being expanded to make Highway 401 six lanes from London to Toronto.^[21] East of Kitchener, the highway meanders towards Milton, passing through several rock cuts along the way.

As Highway 401 approaches the Greater Toronto Area (GTA), it descends through the ecologically protected Niagara Escarpment to the west of Milton.^[22][23] After passing though the town, it enters the western side of Toronto's Greenbelt, a zone around Toronto protected from development.^[22] After this 10 km (6.2 mi) gap, the highway enters the first urbanized section of the GTA, passing through only a few rural areas between the cities of Mississauga and Oshawa.^[14][24]

As the 401 approaches the large Highway 403 / Highway 410 junction in Mississauga, it widens into a collector-express system,^[25] a concept inspired by the Dan Ryan Expressway in Chicago.^[5] This section of the 401 swells to a total of eighteen through lanes south of Toronto's International Airport.^[7] Progressing eastward, the collector lanes diverge to Highway 427,^[26] and eight lanes are carried beneath the large spaghetti junction. The highway then curves northeast and follows a power transmission corridor to Highway 409, which merges with the mainline and forms the collector lanes. The highway returns to its eastward route through Toronto, now carrying fourteen to sixteen lanes of traffic on four separate carriageways.^[26][27]

To manage traffic through this heavily travelled section of roadway, Highway 401 was equipped with a traffic camera system called COMPASS in early 1991.^[28] Using a combination of closed-circuit television cameras, vehicle detection loops and LED changeable message signs, COMPASS allows the Ontario Ministry of Transportation Traffic Operations Centre to obtain a real-time assessment of traffic conditions and alert drivers of collisions, congestion and construction.^[29] The system currently stretches from the Highway 403 / 410 interchange in Mississauga to Harwood Avenue in Ajax.^[30]

The 401 is usually congested in this section, with an average of over 430,000 vehicles passing between Weston Road and Highway 400 per day as of 2006.^[6][7] In spite of this congestion, it is the primary commuting route in Toronto; over 50% of vehicles bound for downtown Toronto use the 401.^[31]

East of Highway 400 is The Basketweave, a criss-crossing transfer between the express and collectors carriageways. Farther east, the 401 approaches Yorkdale Mall.^[32] Twelve lanes pass beneath a complicated interchange with Allen Road, built to serve the cancelled Spadina Expressway. Further east, the highway crosses Hogg's Hollow, over the West Don River, and interchanges with Yonge Street in the centre of Toronto. After passing through a predominantly residential area, the 401 crosses the East Don River and climbs toward the Don Valley Parkway, which provides access to downtown Toronto and Highway 404, which provides access to the suburbs to the north. Progressing beyond the Don Valley Parkway / Highway 404 interchange, the highway continues through mostly residential areas in Scarborough, eventually passing to the north of the Scarborough Town Centre, another large mall. The highway continues east through suburban Toronto, finally reaching the Rouge Valley on the city's eastern edge and crossing into Pickering.^[33]

At Pickering, the highway again meets the former Highway 2, which parallels the 401's route to the Quebec border.^[14] As the highway approaches Brock Road in Pickering, the collector and express lanes converge, narrowing the fourteen lane cross-section to ten, divided only at the centre.^[27] It remains this width as it passes into Ajax,^[34] before narrowing back to six lanes at Salem Road.^[35]

The stretch of the 401 which runs through Whitby and Oshawa features several structures which were built during the initial highway construction in the early 1940s.^[36] Several of these structures, including the former CN overpass, are slated for demolition, either due to their age, or to prepare for the planned widening of Highway 401 through this area.^[37] At Harmony Road, the suburban surroundings are quickly replaced by agricultural land. The highway swings south of Bowmanville and towards Highway 35 and Highway 115.^[24]

Highway 401 uses a collector-express roadway configuration within the GTA. The system divides each direction of travel into collectors and express lanes.^[38] This gives the highway a wide span and four carriageways. To avoid confusion on signs along the collector and express carriageways, the 401 uses blue signs over the collector lanes and green signs over the express lanes. Unlike the collector lanes, which provide access to every interchange, the express lanes only provide direct access to a select few. Access between the two is provided by transfers, which are strategically placed to prevent disruptions such as weaving caused by closely-spaced interchanges.^[39] The overall purpose of the 401's collector-express system is to maximize traffic flow for both local and long-distance traffic and, along with the COMPASS system, to manage traffic flow.^[29]

Highway 401 employs two sets of collector-express systems along its length. The first set is currently 6.6-km (4.1 mi) long and stretches between Kennedy Road and Highway 427.^[40] This system primarily serves to accommodate and organize various traffic movements from the Highway 403 / 410 and Highway 427 interchanges along Highway 401. East of the interchange with Renforth Drive, the collector lanes diverge to become the on-ramps to Highway 27, 427 and Eglinton Avenue. The express lanes carry Highway 401 beneath the Highway 427 interchange towards Highway 409, where the second collector-express system begins. This 43.7 km (27.2 mi) system passes through the centre of Toronto and ends in Pickering to the east.^[41] The highway is at least 10 lanes wide between Highway 427 and Salem Road in Ajax, a distance of 50.9 km (31.6 mi).^[41] It is believed to be the longest continuous stretch of highway in the world having more than 10 lanes.^[42]

The 5 kilometres (3.1 mi) gap between the two systems is a traffic bottleneck,^[36] with eight through lanes at its narrowest point in comparison to a minimum of twelve in adjacent sections.^[43] The Highway 427 interchange cannot currently accommodate future widening of Highway 401.^[36]

East of Highway 35 and Highway 115 to Cobourg, the 401 passes through a mix of agricultural land and forests, maintaining a straight course.^[44] As the highway passes through Cobourg, it narrows to four lanes and enters the Canadian Shield, an ancient, rocky geological formation. The terrain becomes undulating, and the highway veers around hills and through valleys along the shores of Lake Ontario.^[45] At Trenton, the highway crosses the Trent Canal and leaves the Shield, returning to an agricultural setting as it heads eastward to Kingston. The Kingston portion of the 401, originally named the Kingston-Bypass, was one of the first sections of the highway to be completed.^[46]

East of Kingston, the highway continues through a predominantly agricultural area alongside the Saint Lawrence River to Gananoque, where it splits with the Thousand Islands Parkway.^[47] The current Highway 401 runs parallel to the parkway several kilometres inland from the river. The Canadian Shield returns through this heavily forested section of the highway. Highway 401 rejoins the Thousand Islands Parkway immediately southwest of Brockville, now heading northeast.^[48]

The remainder of the highway runs parallel to the former Highway 2 along the shore of the Saint Lawrence River within the St. Lawrence Valley. Northeast of Brockville is the interchange with Highway 416, which heads north towards Ottawa.^[49] At the Quebec border, Highway 401 becomes Autoroute 20 and continues to Montreal.^[50]

Highway 401's history predates its designation by over two decades. As automobile use in southern Ontario grew in the early twentieth century, road design and construction advanced significantly. Following frequent erosion of the former macadamized Lake Shore Road,^[51] a cement road known as the Toronto–Hamilton Highway was proposed in January 1914.^[52] The highway was designed to run along the lake shore, instead of Dundas Street to the north, because the numerous hills encountered along Dundas would have increased costs without improving accessibility. Middle Road, a dirt lane named because of its position between the two, was not considered since Lake Shore and Dundas were both overcrowded and in need of serious repairs.^[53] By November 1914, the proposal was approved,^[54] and work began quickly to construct the road from Toronto to Hamilton known today as Lake Shore Boulevard and Lakeshore Road. The road was formally opened on November 24, 1917,^[51] 18 feet (5.5 m) wide and nearly 40 mi (64 km) long. It was the first concrete road in Ontario, as well as one of the longest stretches of concrete road between two cities in the world.^[55]

Over the next decade, vehicle usage increased substantially, and by 1920 Lakeshore Road was again highly congested on weekends.^[56] In response, the Department of Highways examined improving another road between Toronto and Hamilton. Middle Road, a continuation of Queen Street west of the Humber River, was chosen to avoid delays on Dundas or Lakeshore. The road was to be more than twice the width of Lakeshore Road at 40 ft (12 m), and would carry two lanes of traffic in either direction.^[57] Construction on what was then known as the Queen Street Extension between Highway 10 and Highway 27 began in early 1931,^[58] and between Highway 27 and the Humber River on November 1, 1931.^[59]

Before the highway could be completed, the 1934 provincial elections brought Mitchell Hepburn into office as premier; Thomas McQuesten was appointed the new minister of the Department of Highways.^[36] McQuesten in turn appointed Robert Melville Smith as deputy minister. Smith, inspired by the German Autobahn's—new "dual-lane divided highways", separated by a depressed grass centre crossing short distances between major cities—modified the design for Ontario roads,^[60] and McQuesten ordered that the Middle Road be converted into this new form of highway.^[61][62][63] A 132 ft (40 m) right-of-way was purchased along the Middle Road. Construction began to convert the existing sections to a divided highway, as well as to build Canada's first cloverleaf interchange at Highway 10.^[57]

Beginning in 1935, McQuesten applied the concept of a second roadway to several projects along Highway 2:^[36] a 4 mi (6.4 km) stretch west of Brockville,^[64][65] a 4.5 km (2.8 mi) stretch from Woodstock eastward,^[64] and a section between Birchmount Road and east of Morningside Avenue in Scarborough Township.^[65] When widening in Scarborough reached the Highland Creek ravine in 1936, east of Morningside, the Department of Highways began construction on a new bridge over the large valley, bypassing the former alignment around West Hill.^[66] From here the highway was constructed on a new alignment to Oshawa, avoiding construction on the congested Highway 2.^[5] As grading and bridge construction neared completion between Highland Creek and Ritson Road in September 1939, World War II broke out and gradually money was siphoned from highway construction to the war effort.^[36]

At the same time, between September 6 and 8, 1939, the Ontario Good Roads Association Conference was held at Bigwin Inn, near Huntsville,^[68] drawing highway engineers from across North America to discuss the new concept of "Dual Highways". On the first day of the convention, McQuesten announced his vision of the freeway: an uninterrupted drive through the scenic regions of Ontario, discouraging local business and local traffic from accessing the highway except at infrequent controlled-access points.^[67] It was quickly announced in the days thereafter that this concept would be applied to a new "trans-provincial expressway", running from Windsor to the Quebec border.^[69]

Highway engineers evaluated various factors, including grading, curve radius, and the narrow median, used along the Middle Road (which was inaugurated on June 3 as The Queen Elizabeth Way),^[70] and began to plan the course of a new dual highway mostly parallel to Highway 2, with precedence given to to areas most hampered by congestion. Unlike the Queen Elizabeth Way (QEW), this highway would not be built along an existing road, but rather on a new right-of-way, avoiding the need to provide an alternative means of access to properties.^[36][67]

Along with immense improvements to machinery and construction techniques over its six-year course, the war provided ample opportunity for planners to conduct a large-scale origin–destination survey of 375,000 drivers, asking what their preferred route would be to get to where they needed to go. Using this information, a course was plotted from Windsor to Quebec, bypassing all towns along the way.^[5][71]

Highway 2S, for Scenic, was the first completed section of new roadway. Built to connect with the Thousand Islands Bridge at Ivy Lea and opened as a gravel road in late 1941 or early 1942,^[72] the road followed the shore of the St. Lawrence River and connected with the western end of the twinned Highway 2 west of Brockville.^[14] While today only a two-lane road, it was a divided and paved four lane roadway in the early 1940s.^[73][74][75]

Following the war, construction resumed on roadways throughout Ontario. The expressway between Highland Creek and Oshawa was completed in December 1947,^[5] while other sections remained on the back burner. The Toronto–Barrie Highway was the primary focus of the Department of Highways at the time, and the onset of the Korean War in 1949 continued to stall the building of highways. Despite the delays, highway minister George Doucette officially announced the plans for construction of the new trans-provincial expressway in 1950, with the Toronto to Oshawa expressway serving as a model for the design.^[36] Work on the most important link, the Toronto Bypass, began in 1951,^[36] but it would not open with that name.

In July 1952 (possibly July 1, the same day Highway 400 was numbered),^[76] the Highland Creek to Oshawa expressway, as well as its new extension to Newcastle and Highway 2S were designated Highway 401,^[5] a move scorned by one critic because of the lack of thought into the names.^[77] That same year, construction wrapped up on the first section of the Toronto Bypass between Weston Road and Yonge Street. Extensions east and west began in 1953; while the eastern extension to Bayview Avenue would open just a year later, the western extension was delayed by Hurricane Hazel's arrival on October 15, 1954, which nearly destroyed the new bridge over the Humber River. The reconstructed bridge would open almost nine months later on July 8, 1955.^[78] The entire bypass, including the widening of Highway 27 into an expressway south of the 401,^[79] was completed in 1956.^[5] Upon its opening, the bypass was described by one reporter as "a motorist's dream" providing "some of the most soothing scenery in the Metropolitan area." The reporter continued, with regard to the eastern section through Scarborough, that it "winds smoothly through pastures across streams and rivers, and beside green thickets. It seems a long way from the big city."^[5]

By this point, word had spread that Ontario was building a 500-mile road without a single traffic light. The story was published in several major newspapers around the continent.^[80][81][82] By 1959, the bypass was a lineup of cars, as 85,000 drivers crowded the roadway, designed to handle a maximum of 48,000 vehicles, on a daily basis.^[5] The convenience of a road to get across the city helped influence the suburban shift in Toronto, and continues to be a driving force of suburban sprawl today.^[76]

Meanwhile, beyond Toronto, the 401 was being built in a patchwork fashion, focusing on congested areas first.^[36] Construction west from Highway 27 began in late 1954,^[46] as did the Kingston Bypass in Eastern Ontario.^[83] Work began to connect the latter with the Scenic Highway in 1955.^[46] By 1956, construction had begun on the segment between Highway 4 in London and Highway 2 in Woodstock, as well as on the section between Windsor and Tilbury.^[84]

By the end of 1960, the Toronto section of the 401 was extended both eastwards and westwards: first, to the east between Newcastle and Port Hope by mid-year, then later to the west between Highway 25 in Milton and Highway 8 south of Kitchener.^[85] By mid 1961, the section between Brighton and Marysville had opened.^[86] The gap to the east, from Highway 28 in Port Hope to Highway 30 in Brighton was opened on July 20, 1961.^[87]

The gaps between Woodstock and Kitchener and between Tilbury and London were completed in late 1961 and 1963, respectively, while the gap between Marysville and Kingston was opened by 1962.^[86] The final sections, from west of Cornwall to Lancaster, were opened in 1963 and 1964.^[86][88] Finally, on October 11, 1968, the Thousand Islands Bypass opened.^[5] This final piece was commemorated with a plaque to signify the "completion" of the 401.

In Toronto, engineers and surveyors were examining the four-lane bypass, while planners set about designing a way to handle the commuter highway. In 1963, transportation minister Charles MacNaughton announced the widening of Highway 401 in Toronto from four to a minimum of twelve lanes between Islington Avenue and Markham Road. The design was taken from the Dan Ryan Expressway in Chicago, which was widened into a collector-express system around the same time.^[5] Construction began immediately. While the plan initially called for construction to end in 1967, it continued for nearly a decade, though a minimum of four lanes were always open. The system was completed in 1972, along with the Highway 27 bypass north of the 401. It included the reconstruction of most of the interchanges along its length into the Parclo A4, as well as a continuous lighting system.^[36]

In January 1965, the Premier of Ontario, John Robarts, designated Highway 401 the Macdonald–Cartier Freeway to honour Sir John A. Macdonald and Sir George-Étienne Cartier, two of Canada's Fathers of Confederation.^[5] Unlike other names later applied to the highway, the Macdonald–Cartier Freeway designation covers the entire length of Highway 401. Although formally designated, it would be 38 years until it was written into law.^[89]

In the 1970s, Highway 401 was widened to six lanes in Durham, but otherwise saw little improvement.^[36] The 1980s saw more sections widened, as well as a new eighteen-lane collector-express system built within Mississauga between Highway 403 / 410 and Highway 427. Plans were made to extend the eastern system from Neilson Road to Brock Road in Pickering in the late 1980s,^[90] and took over a decade to reach fruition by 2000.^[91][92] This was followed shortly thereafter by the widening of the highway through Ajax and a new interchange at Pickering Beach Road (renamed Salem Road) and Stevenson Road.^[93]

The 1990s also saw the first step in widening the highway to six lanes from Toronto to London.^[94] A project in the mid-nineties brought the highway up to a minimum of six lanes between Highway 8 in Kitchener and Highway 35 / 115 in Newcastle.^[95] Other projects prepared sections for eventual widening.^[96]

In 1993, the stretch of Highway 401 eastbound near Milton and westbound near Whitby had chevrons painted in each lane in an effort to reduce tailgating, a concept borrowed from France and Britain. Signs advised motorists to keep at least two chevrons apart, in essence warning them not to follow too closely.^[97] Some of these chevrons remain intact in the westbound lanes in Whitby, though the signs stating their use have since been removed.^[98]

Beginning in 1998, several projects were initiated on Highway 401 within Toronto. These included the addition of one lane through the Highway 427 interchange in 2005, as well as the resurfacing of the pavement.^[99]

Between June 1990 and 1998, Highway 401 and Interstate 75 were used for a pilot project named Advantage I-75 to test out the reliability and versatility of an automated tracking system for transport trucks. Termed MACS for Mainline Automated Clearance System, it would allow a truck to travel from Florida to Ontario without a second inspection.^[100] MACS was initially tested out at two truck inspection stations in Kentucky, with transponders installed in 220 trucks. Exact time, date, location, weight and axle data were logged as a truck approached an equipped station.^[101] Following initial tests, MACS was deployed at every inspection station along I-75 from Miami to Detroit, and along Highway 401 from Windsor to Belleville in 1994.^[100] The project demonstrated the effectiveness of electronic systems in enforcing freight restrictions without delaying vehicles, while alleviating security fears that such systems could be easily compromised. The concept has since been applied to many parts of Canada, including Highway 407's electronic tolling system.^[102]

Around the same time, the section of Highway 401 between Windsor and London became known as Carnage Alley, a reference to the numerous accidents that occurred over that stretch of the highway throughout the 1990s.^[36] Various other names, including The Killer Highway circulated for a time,^[103] but Carnage Alley became predominant following an 87-vehicle pile-up on September 3, 1999, the worst in Canadian history.^[104]

Only a few days prior, then-Transportation Minister David Turnbull had deemed the highway "pleasant" to drive.^[105] On the morning of September 3, the local weather station reported clear conditions due to a malfunction,^[104] while a thick layer of fog rolled onto the highway. The unimproved section of road with an open grass median proved fatal to seven people, as 87 vehicles quickly crashed into each other shortly after 8 am,^[106] one following another in the dense fog.^[107]

Immediately following the accident, the MTO installed paved shoulders with rumble strips^[108] and funded additional police to patrol the highway, a move criticized as being insufficient.^[109] Beginning in 2004, 46 km (29 mi) of the highway was widened from four asphalt lanes to six concrete lanes, paved shoulders were added, a concrete Ontario Tall Wall median was installed,^[110] interchanges were improved and signage was upgraded as part of a five-phase project to improve the 401 from Highway 3 in Windsor to Essex County Road 42 (formerly Highway 2) on the western edge of Tilbury.^[111] In the first quarter of 2007, Bill 203, the Safer Roads for a Safer Ontario Act was introduced to parliament by ERASE (Eliminate Racing Activities on Streets Everywhere), a campaign created by local and provincial police.^[112][113] The law, passed September 30, 2007, allows police to immediately suspend the driver’s licence and impound the vehicle involved for seven days in the case of "excessive speeding" (driving 50 kilometres per hour (31 mph) over the limit, or over 150 km/h (93 mph) on 400-series highways).^[114][115] Transport truck maximum speed is also limited, by speed governors, to 105 km/h, as in nearby Quebec.^[116]

On August 24, 2007, the MTO announced that the stretch of Highway 401 between Glen Miller Road in Trenton and the intersection of the Don Valley Parkway and Highway 404 in Toronto would bear the additional name Highway of Heroes, in honour of Canada's fallen soldiers,^[117] though Highway 401 in its entirety remains designated as the Macdonald–Cartier Freeway.^[118] This length of the highway is often travelled by a convoy of vehicles carrying a fallen soldier's body, with his or her family, from CFB Trenton to the coroner's office at the Centre for Forensic Sciences in Toronto. Since 2002, when the first of Canada's fallen soldiers were returned from Afghanistan, crowds have lined the overpasses to pay their respects as convoys pass.^[119]

The origin of the name can be traced to a June 25, 2007 article in the Toronto Sun by columnist Joe Warmington, in which he interviewed Northumberland columnist and photographer Pete Fisher. Warmington described the gathering of crowds on overpasses to welcome fallen soldiers as a "highway of heroes phenomena."^[120] This led Crahame Township volunteer firefighter Ken Awender to contact Fisher on July 10 about starting a petition, leading Fisher to publish an article in the Cobourg Daily Star and Port Hope Evening Guide three days later. This article was in turn posted to the Northumberland Today website.^[121] The online article was picked up by several media outlets, and eventually caught the attention of London resident Jay Forbes. Forbes began a petition, which received over 20,000 signatures^[117] before being brought to the attention of Ontario transportation minister Joanne Cansfield on August 22.^[122] Following the announcement on August 24, the provincial government and MTO set out to design new signs. The signs were erected and unveiled on September 7,^[118] and include a smaller reassurance marker (shield) with a poppy and the text "Highway of Heroes" in place of a number, as well as a larger billboard version with English and French text. A French translation of the poppy shield is also posted within Toronto.

On Sunday August 10, 2008, following a series of explosions at a propane facility in Toronto, Highway 401 was closed between Highway 400 and Highway 404 as a precautionary measure.^[123] The highway remained closed until 8 pm, though several exits near the blast remained closed thereafter.^[124][125] The entire width of Highway 401 through central Toronto was closed as a result, the first time the highway was fully closed since the Toronto Bypass opened in 1956.

Between 2006 and 2008, a widening project was completed in London, widening Highway 401 from four to six lanes between Highway 402 and Wellington Road.^[111] This included significant reconstruction of the Wellington Road interchange, replacing the outdated 3/4 cloverleaf with a parclo A-4 containing a sub-collector system. The overpass was also replaced, allowing it to support a future ten-lane 401, compared with the old overpass built in 1956 that could only support four lanes.

The MTO intends to widen all of the remaining four-lane sections to a minimum of six and place an Ontario Tall Wall along the entire length of the highway.^[110][126]

In 2004, it was announced that a new border crossing would be constructed between Detroit and Windsor. The Detroit River International Crossing (DRIC) was formed as a bi-national committee to manage the project.^[127] The MTO took advantage of this opportunity to extend Highway 401 to the international border and began an environmental assessment on the entire project in late 2005.^[127] The City of Windsor also hired New York traffic consultant Sam Schwartz to design a parkway to the border. Schwartz's proposal would eventually inspire the DRIC's own design, but his route was not chosen, with the DRIC opting instead to take a northern route.^[128] On February 8, 2008, the MTO announced that it had began purchasing property south of the E.C. Row Expressway, upsetting many area residents who had purchased properties in the years prior.^[129][130]

On March 3, 2008, the Michigan Department of Transportation and the MTO (in partnership with Transport Canada, the Federal Highway Administration of the United States and the Detroit River International Crossing group) completed a joint assessment on the soils along the Detroit River, and determined that they could indeed support the weight of a new bridge; the stability of the underlying soil and clay, and the impact of the nearby Windsor Salt mine, had caused a great deal of concern for all parties involved in the project.^[131]

On May 1, 2008, it was announced that the extension of the 401 would be named the Windsor–Essex Parkway, and a preferred route was selected.^[12] The new parkway will be below-grade and have 6 through-lanes. It will follow (but not replace) Talbot Road and Huron-Church Road from a new interchange at the current end of Highway 401 to the E.C. Row Expressway, where it will run concurrently westward for 2 km (1.2 mi). From there, it will turn northwest and follow a new alignment to the border.^[132] Initial construction of a new bridge south of the Highway 3/401 junction, as well as a noise barrier from North Talbot Road to Howard Avenue began in the third quarter of 2009. The project has an expected completion date of 2013.^[133]

In Southwestern Ontario, several improvements are under way to provide six lanes on the 401 from Windsor to Toronto,^[126] in response to the Carnage Alley pile-up in 1999.^[110][134] West of Manning Road, the highway is currently being widened in anticipation of the Windsor–Essex Parkway.^[12][135] Between Tilbury and Highway 402, the 401 remains four lanes wide with a grass median. The widening and upgrading of this section is in the planning stages, with construction possibly beginning in 2012 and lasting for several years. Several interchanges are slated to be upgraded as part of this construction.^[136]

Within the London area, a new interchange with Wonderland Road is in the planning stages to help improve access to Highway 401 westbound from the city's southwest end. This may also include partial interchanges along White Oaks Road with Highway 401 and 402.^[137] This project will coincide with reconstructing the outdated cloverleaf interchange at Colonel Talbot Road^[138] and widening Highway 401 from four to six lanes between Highway 4 and Highway 402. Construction could start as early as 2013.^[139] In addition, an environmental assessment is underway to examine the impact of reconstructing the three-way trumpet interchange with the Veterans Memorial Parkway into a four-way interchange in order to extend the expressway south of the 401.^[140][141] The MTO has also proposed widening Highway 401 from six to eight lanes through London.^[142]

East of London, widening the highway to six lanes with a tall wall median and paved shoulders between Woodstock and Kitchener is a priority for the MTO. The completion of this remaining four-lane gap will bring the entire London–Toronto segment up to six lanes.^[21] Long term plans call for Highway 401 in the Waterloo region to be widened to eight lanes as well. The interchange between Highway 401 and Highway 8 (King Street) is to be reconstructed to make it free-flowing for all directions of travel, easing congestion and improving traffic flow in the area.^[143]

In their 2007 plan for southern Ontario, the MTO announced long-term plans to create HOV-lanes from Mississauga Road west to Milton.^[144] Construction is also underway to widen Highway 401 to a 12-lane collector-express system from Highway 403 and Highway 410 west to Hurontario Street.^[145]

Within Toronto, a select number of projects are being completed during overnight construction projects, including the widening and rehabilitation of the Hogg's Hollow bridge,^[146] the replacement of the original gantries throughout the collector-express system,^[147] and reconstructing the Highway 401/400 interchange.^[148]

In Oshawa, Exit 416 (Park Road) was replaced by a new interchange at Exit 415 (Stevenson Road). The contract, which began September 7, 2005, included the interchange and the resurfacing of 23.4 km (14.5 mi) of the highway between Oshawa and Highway 35 / Highway 115, at a total cost of $65,097,000.00.^[149] The westbound ramps were opened in mid-September 2007^[150] and the eastbound ramps in mid-2009. The resurfacing is expected to be completed by July 31, 2010.^[149]

Current expansion plans in Durham include the construction of two new freeways north from the 401. The first will be directly east of Durham Regional Road 23 (Lakeridge Road),^[151] while the second will lie to the east of Durham Regional Road 34 (Courtice Road).^[152] Following the 407 east extension's approval, Highway 401 will be widened to twelve lanes, forming an extension to the current collector-express system, from its current end at Durham Regional Road 1 (Brock Road) in Pickering to Durham Regional Highway 12 (Brock Street) in Whitby.^[153] Long term plans also call for HOV lanes to run from Brock Road to Durham Regional Road 33 (Harmony Road), though no planning has commenced.^[144]

East of Durham, the MTO is planning to widen the entire length of the highway to 6 lanes.^[126] Preliminary work includes the widening of the bridge over the Trent River in Trenton,^[154] as well as the realignment of some roads alongside the highway.^[155] By mid 2012, the 401 will be widened for 6 kilometres through Kingston.^[156]

Highway 401 features 19 service centres controlled by the MTO. These service centres were announced in 1961 following public outcry to the lack of rest stops. They provide a place to park, rest, eat and refuel 24 hours a day.^[5]

The centres were originally leased to and operated by several major gasoline distributors; however, those companies have chosen not to renew their leases as the terms end. In response, the MTO put the operation of the full network of service centres out for tender, resulting in a 50-year lease with Host Kilmer Service Centres, a joint venture between hospitality company HMSHost (a subsidiary of Autogrill) and Larry Tanenbaum's investment company Kilmer van Nostrand.^[157]

Seventeen of the centres along the 401 will be reconstructed entirely. Two centres that were rebuilt in the late 1990s, specifically Newcastle and the westbound location at Woodstock, will not be redeveloped at this time.

Work on 15 of the 17 service centres to be reconstructed began in late 2009 or early 2010. The new service centres, to open in phases beginning in July 2010, will feature a Canadian Tire gas station and convenience store, as well as fast food brands such as Tim Hortons, A&W and Burger King.^[158]

Service centres are located at the following points along Highway 401:

Division	Location	km[6]	Exit[14]	Destinations	Notes
Essex	Windsor	0.0		Highway 3 west – Ambassador Bridge to US	Westbound exit and eastbound entrance
		2.6	13	Dougall Avenue – Detroit-Windsor Tunnel to US	Westbound exit and eastbound entrance; formerly Highway 3B / Highway 401A
		3.4	14	County Road 46 (Walker Road) – Windsor	Formerly  Highway 98
	Tecumseh	10.4	21	County Road 19 (Manning Road) – Tecumseh
	Lakeshore
		17.5	28	County Road 25 (Puce Road) – Puce
		23.7	34	County Road 27 (Belle River Road) – Woodslee, Belle River
		30.0	40	County Road 31 (French Line Road) – St. Joachim
		37.3	48	Highway 77 south – Leamington  County Road 35 north (Comber Road) – Stoney Point
		45.7	56	County Road 42 – Tilbury	Formerly  Highway 2
Chatham-Kent	Tilbury	52.8	63	Municipal Road 2 (Queen's Line)	Formerly Highway 2
	Chatham	70.9	81	Municipal Road 27 (Bloomfield Road)
		79.3	90	Highway 40 north  Municipal Road 11 south (Communication Road) – Blenheim
		91.0	101	Municipal Road 15 (Kent Bridge Road) – Dresden, Ridgetown
		98.3	109	Municipal Road 17 / Municipal Road 21 (Victory Road) – Thamesville, Ridgetown	Formerly  Highway 21
		106.2	117	Municipal Road 20 (Orford Road) – Highgate
Elgin	West Elgin	119.2	129	County Road 103 (Furnival Road) – Wardsville, Rodney
		127.3	137	County Road 76 (Graham Road) – West Lorne	Formerly  Highway 76
	Dutton/Dunwich	138.5	149	County Road 8 (Currie Road) – Dutton
		147.4	157	County Road 14 (Iona Road) – Melbourne, Iona
	Southwold
		154.1	164	County Road 20 (Union Road) – Port Stanley, Shedden
Middlesex	London	166.7	177	Highway 4 (Colonel Talbot Road) – St. Thomas	Signed as exits 177A (south) and 177B (north)
		173.2	183	Highway 402 west – Sarnia	Westbound exit and eastbound entrance
		175.9	186	Wellington Road
		176.8	187	Exeter Road	Formerly  Highway 135 west
		179.1	189	Highbury Avenue – St. Thomas	Formerly  Highway 126
		183.6	194	Veterans Memorial Parkway	Formerly  Highway 100
	Thames Centre	185.5	195	County Road 74 (Westchester Bourne) – Nilestown, Belmont	Formerly  Highway 74
		189.3	199	County Road 32 (Dorchester Road) – Dorchester
		193.0	203	County Road 73 (Elgin Road) – Aylmer	Formerly  Highway 73
		198.5	208	County Road 30 (Putnam Road) – Putnam, Avon
Oxford	South-West Oxford, Ingersoll	206.0	216	County Road 10 (Culloden Road)
		208.5	218	Highway 19 south  County Road 119 north (Plank Line) – Tillsonburg
	South-West Oxford	212.2	222	County Road 6 – Stratford
		219.8	230	County Road 12 (Sweaburg Road / Mill Street) – Sweaburg
	Woodstock
		221.9	232	County Road 59 – Delhi	Formerly  Highway 59
		225.3	235	Highway 403 east – Brantford, Hamilton	Eastbound exit and westbound entrance
	Norwich
		226.3	236	County Road 15 (Towerline Road) – Woodstock
		227.9	238	County Road 2 – Paris, Woodstock	Formerly Highway 2
	Woodstock
	Blandford-Blenheim	240.1	250	County Road 29 (Drumbo Road) – Innerkip, Drumbo
Waterloo	North Dumfries	257.9	268	Regional Road 97 (Cedar Creek Road) – Cambridge, Ayr	Signed as exits 268A (east) and 268B (west) eastbound; formerly  Highway 97
	Kitchener, Cambridge	265.0	275	Regional Road 28 (Homer Watson Boulevard / Fountain Street)	Replaced Doon-Blair Road exit in the 1970s
		267.9	278	Highway 8 north – Kitchener, Waterloo  Regional Road 8 south – Cambridge	Signed as exits 278A (east) and 278B (west) eastbound
	Cambridge	272.5	282	Regional Road 24 (Hespeler Road) to  Highway 24
			284	Regional Road 36 south (Franklin Boulevard)	Eastbound exit and westbound entrance
		276.5	286	Regional Road 33 (Townline Road)  County Road 33 (Townline Road)
Wellington	Puslinch
		285.7	295	Highway 6 north – Guelph	West end of Highway 6 overlap
		290.1	299	Highway 6 south – Hamilton  County Road 46 (Brock Road) – Guelph, Hamilton	East end of Highway 6 overlap
Halton	Milton	301.9	312	Regional Road 1 (Guelph Line) – Burlington
		310.1	320	Regional Road 25 – Acton, Milton	Formerly  Highway 25; GO Transit bus stop on eastbound ramp.
		313.8	324	Regional Road 4 (James Snow Parkway)
		318.0	328	Regional Road 3 (Trafalgar Road) – Oakville, Georgetown
		320.4	330A	Highway 407 west	Signed as exit 330 westbound
		320.4	330B	Highway 407 east	Eastbound exit and westbound entrance
Peel	Mississauga	322.7	333	Winston Churchill Boulevard
		326.1	336	Regional Road 1 (Mississauga Road / Erin Mills Parkway)
		329.6	340	Mavis Road
		331.7	342	Hurontario Street	Formerly  Highway 10
		334.5	344	Highway 410 north – Brampton	Eastbound exit and westbound entrance
		334.5	344	Highway 403 / Highway 410 – Hamilton, Brampton	Westbound exit and eastbound entrance
		336.0	346	Regional Road 4 (Dixie Road)
		340.3–341.1	348	Highway 427 / Renforth Drive – Toronto Pearson International Airport, Downtown Toronto	Eastbound exit and westbound entrance
Toronto		341.1	350	Eglinton Avenue	Eastbound exit and westbound entrance
			351	Carlingview Drive	Westbound exit and eastbound entrance
			352	Highway 427 south	Westbound exit and eastbound entrance
		343.5	354	Dixon Road / Martin Grove Road
			355	Highway 409 – Toronto Airport Belfield Road	Westbound exit and eastbound entrance
		346.0	356	Islington Avenue
		347.4	357	Weston Road
		348.9	359	Highway 400 north (south to Black Creek Drive) – Barrie	Express exits 359 eastbound to Highway 400 only.
		350.5	360	Jane Street	Ramps removed, access to Jane Street via Black Creek Drive.
		352.0	362	Keele Street
		354.0	364	Dufferin Street, Yorkdale Road	Eastbound exit and westbound entrance
		354.8	365	Allen Road, Yorkdale Road
		356.2	366	Bathurst Street	Westbound exit and eastbound entrance
		357.3	367	Avenue Road	Formerly  Highway 11A
		359.0	369	Yonge Street	Formerly  Highway 11
		361.0	371	Bayview Avenue
		362.9	373	Leslie Street
		364.9	375	Highway 404 north – Richmond Hill, Newmarket Don Valley Parkway – Downtown Toronto
		366.3	376	Victoria Park Avenue
		367.6	378	Warden Avenue
		369.2	379	Kennedy Road
		370.8	380	Brimley Road south, Progress Avenue	Eastbound exit and westbound entrance from northbound Brimley Road
		371.6	381	McCowan Road
		373.2	383	Markham Road	Formerly  Highway 48
		375.0	385	Neilson Road
		376.5	387	Morningside Avenue
		379.0	389	Meadowvale Road
		380.3	390	Highway 2 / Highway 2A (Kingston Road, Sheppard Avenue (westbound), Port Union Road (eastbound))	Signed as exit 392 westbound
Durham	Pickering		394	Regional Road 38 (Whites Road)
			397	Regional Road 29 (Liverpool Road)	Westbound exit and entrance
			399	Regional Road 1 (Brock Road)
	Ajax		400	Church Street	Removed, exit replaced with nearby Westney Road interchange (Exit 401) in 1988
			401	Regional Road 31 (Westney Road)	Replaced Exit 400 (Church Street) in 1988
			403	Regional Road 44 (Harwood Avenue)	Removed, exit replaced with nearby Salem Road interchange (Exit 404) in 2003
			404	Regional Road 41 (Salem Road)	Replaced Exit 403 (Harwood Avenue) in 2003
	Whitby		410	Regional Highway 12 (Brock Street)	Formerly  Highway 12
			412	Regional Road 26 (Thickson Road)
	Oshawa		415	Regional Road 53 (Stevenson Road)	Replaced Exit 416 (Park Road) in 2009
			416	Regional Road 54 (Park Road)	Removed, exit replaced with nearby Stevenson Road interchange (Exit 415) in 2009
			417	Regional Road 2 (Simcoe Street)	Westbound exit is via exit 418
			418	Regional Road 16 (Ritson Road)
			419	Regional Road 22 / Regional Road 33 (Bloor Street / Harmony Road)
	Clarington		425	Regional Road 34 (Courtice Road) – Courtice
			428	Holt Road (Darlington Nuclear Generating Station)	Eastbound exit and westbound entrance
			431	Regional Road 57 (Waverley Road) – Bowmanville
			432	Regional Road 14 (Liberty Street) – Bowmanville, Port Darlington
			435	Bennett Road
			436	Highway 35 / Highway 115 – Peterborough, Lindsay
			440	Regional Road 17 (Mill Street) – Newcastle, Bond Head
			448	Regional Road 18 (Newtonville Road) – Newtonville
Northumberland	Port Hope		456	Wesleyville Road
			461	County Road 2 – Welcome	Formerly Highway 2
			464	County Road 28 – Peterborough	Formerly  Highway 28
	Cobourg, Hamilton		472	County Road 18 (Burnham Street) – Gores Landing
			474	County Road 45 – Norwood, Baltimore	Formerly  Highway 45
	Alnwick/Haldimand		487	County Road 23 (Lyle Street) – Centreton, Grafton
	Cramahe		497	County Road 25 (Percy Street / Big Apple Drive) – Colborne, Castleton
	Brighton		509	County Road 30 – Brighton	Formerly  Highway 30
Hastings	Quinte West		522	County Road 40 (Wooler Road) – Trenton
			525	County Road 33 – Trenton, Batawa	Formerly  Highway 33
			526	County Road 4 (Glen Miller Road) – Trenton
			538	County Road 1 (Wallbridge-Loyalist Road) – Stirling
	Belleville
			543	Highway 62 – Marmora, Madoc to  County Road 14	Signed as exits 543A (south) and 543B (north); formerly Highway 14
			544	Highway 37 – Tweed
	Tyendinaga		556	County Road 7 (Shannonville Road) – Shannonville, Tyendinaga Mohawk Territory
			566	Highway 49  County Road 15 (Marysville Road) – Picton, Tyendinaga Mohawk Territory
			570	County Road 10 (Deseronto Road) – Deseronto
Lennox and Addington	Greater Napanee
			579	County Road 41 – Napanee	Formerly Highway 41
			582	County Road 5 (Palace Road) – Napanee
	Loyalist		593	County Road 4 (Camden East Road) – Millhaven, Camden East	Formerly [[Ontario Highway 133|Highway 133}}
			599	County Road 6 (Wilton Road) – Yarker, Odessa
Frontenac	Kingston		611	County Road 38 – Harrowsmith, Sharbot Lake	Formerly Highway 38
			613	County Road 9 (Sydenham Road), Sydenham
			615	Sir John A. Macdonald Boulevard
			617	County Road 10 (Division Street) – Westport
			619	County Road 11 (Montreal Street) – Battersea
			623	Highway 15 – Smiths Falls, Ottawa, CFB Kingston
			632	County Road 16 (Joyceville Road) – Joyceville
Leeds and Grenville	Gananoque, Leeds and the Thousand Islands		645	County Road 32 – Crosby	Formerly Highway 32
			647	Thousand Islands Parkway – Ivy Lea, Rockport	Eastbound exit and westbound entrance
	Leeds and the Thousand Islands		648	Highway 2 – Gananoque  County Road 2	Eastbound via exit 647
			659	County Road 3 (Reynolds Road) – Ivy Lea, Rockport
			661	Highway 137 ( I-81 to US)
	Front of Yonge		675	County Road 5 (Mallorytown Road) – Mallorytown, Rockport
	Elizabethtown-Kitley		685	Thousand Islands Parkway	Westbound exit and eastbound entrance
			687	County Road 2 – Brockville	Formerly Highway 2
	Brockville		696	County Road 29 – Brockville	Formerly Highway 29 / Highway 42
			698	North Augusta Road – Brockville, North Augusta
	Augusta		705	County Road 15 (Maitland Road) – Merrickville, Maitland
	Prescott		716	County Road 18 (Edward Street) – Prescott, Domville
	Edwardsburgh/Cardinal		721A	Highway 416 north – Ottawa	Eastbound exit and westbound entrance; signed as exit 721 eastbound
			721B	Highway 16 (to NY 37) – Kemptville, Johnstown, US	Signed as exit 721 westbound
			730	County Road 22 (Shanly Road) – Cardinal
Stormont, Dundas and Glengarry	South Dundas		738	County Road 1 (Carman Road) – Iroquois
			750	County Road 31 – Ottawa, Winchester	Formerly Highway 31
			758	Upper Canada Road
	South Stormont		770	County Road 14 (Dickinson Drive) – Ingleside
			778	County Road 35 (Moulinette Road) – Long Sault
			786	County Road Power Dam Drive	Eastbound exit and westbound entrance
	Cornwall		789	Highway 138 (Brookdale Avenue) – Ottawa, Three Nations Crossing to US
			792	McConnell Avenue
			796	County Road 44 (Boundary Road)
	South Glengarry
			804	County Road 27 (Summerstown Road) – Summerstown
			814	County Road 2 / County Road 34 – Lancaster, Alexandria	Formerly Highway 2 south / Highway 34 north
			825	County Road 23 (4th Line Road, Curry Hill Road)
Continues as A-20 towards Montreal, QC
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