Grade separation in the context of "A40 road in London"

The National Roads and Motorways in Greece constitute the main road network of the country. These two types of roads are distinct in terms of their construction specifications. Their main difference is that motorways (Greek: Αυτοκινητόδρομοι) adhere to higher quality construction standards than National Roads (Greek: Εθνικές Οδοί).

For example, a typical motorway (highway) in Greece consists of six or four lanes (three or two lanes in each direction) plus an emergency lane, separated by a central barrier. Entrances and exits to the motorways are only provided at grade-separated junctions (interchanges) and there are no traffic lights. Greek motorways are generally organized so that the odd-numbered motorways are of north-south alignment and the even-numbered motorways are of east-west alignment. However, there are many exceptions.

Rapid transit, mass rapid transit (MRT) or rail rapid transit (RRT) and commonly referred to as metro, is a type of high-capacity public transport that is generally built in urban areas. A grade separated rapid transit line below ground surface through a tunnel can be regionally called a subway, tube, metro or underground. They are sometimes grade-separated on elevated railways, in which case some are referred to as el trains – short for "elevated" – or skytrains. A common alternative term for rapid transit in North America is heavy rail. Rapid transit systems are usually electric railways that, unlike buses or trams, operate on an exclusive right-of-way, which cannot be accessed by pedestrians or other vehicles.

Modern services on rapid transit systems are provided on designated lines between stations typically using electric multiple units on railway tracks. Some systems use guided rubber tires, magnetic levitation (maglev), or monorail. The stations typically have high platforms, without steps inside the trains, requiring custom-made trains in order to minimize gaps between train and platform. They are typically integrated with other public transport and often operated by the same public transport authorities. Some rapid transit systems have at-grade intersections between a rapid transit line and a road or between two rapid transit lines.

In the field of road transport, an interchange (American English) or a grade-separated junction (British English) is a road junction that uses grade separations to allow for the movement of traffic between two or more roadways or highways, using a system of interconnecting roadways to permit traffic on at least one of the routes to pass through the junction without interruption from crossing traffic streams. It differs from a standard intersection, where roads cross at grade. Interchanges are almost always used when at least one road is a controlled-access highway (freeway) or a limited-access highway (expressway), though they are sometimes used at junctions between surface streets.

An overpass, called an overbridge or flyover (for a road only) in the United Kingdom and some other Commonwealth countries, is a bridge, road, railway or similar structure that is over another road or railway. An overpass and underpass together form a grade separation. Stack interchanges are made up of several overpasses.

Rapid transit, mass rapid transit (MRT) or rail rapid transit (RRT) and commonly referred to as metro, is a type of high-capacity public transport that is generally built in urban areas. A grade separated rapid transit line below ground surface through a tunnel can be regionally called a subway, tube, metro or underground. They are sometimes grade-separated on elevated railways, in which case some are referred to as elevated, el or L trains – short for "elevated" – or skytrains. A common alternative term for rapid transit in North America is heavy rail. Rapid transit systems are usually electric railways that, unlike buses or trams, operate on an exclusive right-of-way, which cannot be accessed by pedestrians or other vehicles.

Modern services on rapid transit systems are provided on designated lines between stations typically using electric multiple units on railway tracks. Some systems use guided rubber tires, magnetic levitation (maglev), or monorail. The stations typically have high platforms, without steps inside the trains, requiring custom-made trains in order to minimize gaps between train and platform. They are typically integrated with other public transport and often operated by the same public transport authorities. Some rapid transit systems have at-grade intersections between a rapid transit line and a road or between two rapid transit lines.

A cloverleaf interchange is a two-level interchange in which all turns are handled by slip roads. To go left (in right-hand traffic; reverse directions in left-driving regions), vehicles first continue as one road passes over or under the other, then exit right onto a one-way three-quarter loop ramp (270°) and merge onto the intersecting road. The objective of a cloverleaf is to allow two highways to cross without the need for any traffic to be stopped by traffic lights. The limiting factor in the capacity of a cloverleaf interchange is traffic weaving.

King's Highway 401, commonly referred to as Highway 401 and also known by its official name as the Macdonald–Cartier Freeway or colloquially referred to as the four-oh-one, is a 400-series highway in the Canadian province of Ontario. It is an 828-kilometre-long (514 mi) freeway, travelling from Windsor in the west to the Ontario–Quebec border in the east (west of Montreal). The part of Highway 401 that passes through Toronto is North America's busiest highway, and one of the widest in Canada. Together with Autoroute 20 (A-20), it forms the road transportation backbone of the Quebec City–Windsor Corridor, along which over half of Canada's population resides. It is also a Core Route in Canada's National Highway System. The route is maintained by the Ministry of Transportation of Ontario (MTO) and patrolled by the Ontario Provincial Police (OPP). The speed limit is 100 km/h (62 mph) throughout the majority of its length, with the remaining exceptions being the posted 80-kilometre-per-hour (50 mph) limit westbound in Windsor, in most construction zones, and the 110-kilometre-per-hour (68 mph) speed limit on the 40-kilometre (25 mi) stretch between Windsor and Tilbury that was raised on April 22, 2022, the 7-kilometre (4.3 mi) extension east of the aforementioned, the 35-kilometre (22 mi) stretch between Highway 35 / 115 and Cobourg, the 44-kilometre (27 mi) stretch between Colborne and Belleville, the 66-kilometre (41 mi) stretch between Belleville and Kingston, and the 107-kilometre (66 mi) stretch between Highway 16 and the east end of the freeway that were raised on July 12, 2024.

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". These three sections of highway were 11.8, 54.7, and 41.2 kilometres (7.3, 34.0, and 25.6 mi), respectively. In 1964, the route became fully navigable from Windsor to the Ontario–Quebec border. In January 1965, it was given a second designation, the Macdonald–Cartier Freeway, in honour of two Fathers of Confederation. At 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 817.9-kilometre (508.2 mi) length. In August 2007, a portion of Highway 401 between Trenton and Toronto has been designated as the Highway of Heroes, as the route is travelled by funeral convoys for fallen Canadian Forces personnel from CFB Trenton to the coroner's office in Toronto.