In road design, a slip lane is a road at a junction that allows road users to change roads without actually entering an intersection. [1] Slip lanes are "helpful... for intersections designed for large buses or trucks to physically make a turn in the space allotted, or where the right turn is sharper than a 90 degree turn." [2] Slip lanes may reduce congestion and "t-bone" motor vehicle collisions, but they increase the risk for pedestrians, cyclists and horse riders who cross the slip lane.
Some intersections that are controlled by traffic light offer a slip lane, which allows users to bypass the lights when they turn. That helps ease congestion and improves journey times, as people who are turning do not have to stop at the light but can continue at the same speed. [3] There are two types of slip lanes at intersections: slip lanes that end and require traffic to merge to join the main road, and slip roads that continue onto the main road as another traffic lane.
They are known as "filter lanes" in the United Kingdom. In right-turn countries, they may be called "channelized right-hand turn lanes."
In Australia, before entering a slip road, drivers must look to ensure that their blind spots are clear of other motorists, cyclists, and pedestrians. Drivers must then give way to any pedestrians crossing the slip road. Before joining the main road from a slip road, drivers must give way to all other traffic even if they are faced with a give-way or with other traffic controls. [4]
In countries such as the United Kingdom in which partial conflicts between pedestrians and vehicular traffic are not permitted, slip lanes can be used as part of a "walk with traffic" facility. Normally, pedestrian signals in the UK operate on a full pedestrian stage in which all traffic is held at red, and all pedestrian crossings are given a green signal. With a slip lane, pedestrians can cross to the triangular island during the vehicle red phase and cross the road while the traffic from their approach has a green light. [5]
The Federal Highway Administration (FHWA) in United States has indicated that "to accommodate safe pedestrian crossings," intersections should be designed "using tight curb radii, shorter crossing distances, and other tools.... While right-turn slip lanes are generally a negative facility from the pedestrian perspective due to the emphasis on easy and fast vehicle travel, they can be designed to be less problematic." [6]
In right-turn countries, designers of right-turn slip lanes may try to increase pedestrian safety by including a range of features. These may include "a raised "island" for pedestrians with a curb and ramps for wheelchair users. To encourage drivers to slow down for crossing pedestrians, edge lines or painted cross-hatching may be used to "narrow the [driver's] perceived width of the lane." [7] As well, pedestrian safety in the crosswalk may be improved with "high-visibility crosswalk striping, flashing beacons, and/or signage" and raised crosswalks. Flashing "warning beacons may be desirable in locations where there are high traffic volumes and vehicle speeds." [8] Some states in the United States require a stop sign at slip lanes to control entry to the main roadway. [9]
The organisation Strong Towns argues that slip lanes exist only to prioritise the speed of motor traffic, and it calls for the removal of slip lanes on local streets. [10]
When poorly designed, slip lanes can be a dangerous design element. For reasons of urban design and pedestrian safety, many road-controlling authorities are actively removing them in urban and suburban settings. [11] [12] Slip lanes may need to be removed if considerations such as pedestrian safety grow to a point that they override the desire to facilitate free passage for drivers. [13] [14] "Slip lanes reduce drivers’ awareness of crossing pedestrians because they are led to focus on the traffic stream into which they are merging, and also impair visibility of the traffic stream because of the angle of approach." [15] As well, "[s]lip lanes also greatly increase crossing complexity for pedestrians and cyclists, by increasing total crossing distance, requiring judgement about crossing fast-moving traffic without the benefit of a traffic signal." [16] To minimise risks of collision, slip lanes can be shaped to enter the traffic flow at an angle higher than the 45 degrees that is shown in the sketch. Such lanes are called high-entry angle slip lanes. [17]
Traffic comprises pedestrians, vehicles, ridden or herded animals, trains, and other conveyances that use public ways (roads/sidewalks) for travel and transportation.
A roundabout, a rotary and a traffic circle are types of circular intersection or junction in which road traffic is permitted to flow in one direction around a central island, and priority is typically given to traffic already in the junction.
An intersection or an at-grade junction is a junction where two or more roads converge, diverge, meet or cross at the same height, as opposed to an interchange, which uses bridges or tunnels to separate different roads. Major intersections are often delineated by gores and may be classified by road segments, traffic controls and lane design.
A pedestrian crossing is a place designated for pedestrians to cross a road, street or avenue. The term "pedestrian crossing" is also used in the Vienna and Geneva Conventions, both of which pertain to road signs and road traffic.
Traffic lights, traffic signals, or stoplights – also known as robots in South Africa and Namibia – are signaling devices positioned at road intersections, pedestrian crossings, and other locations in order to control the flow of traffic.
Road traffic safety refers to the methods and measures used to prevent road users from being killed or seriously injured. Typical road users include pedestrians, cyclists, motorists, vehicle passengers, and passengers of on-road public transport.
A curb extension is a traffic calming measure which widens the sidewalk for a short distance. This reduces the crossing distance and allows pedestrians and drivers to see each other when parked vehicles would otherwise block visibility. The practice of banning car parking near intersections is referred to as daylighting the intersection.
Jaywalking is the act of pedestrians walking in or crossing a roadway if that act contravenes traffic regulations. The term originated in the United States as a derivation of the phrase jay-drivers, people who drove horse-drawn carriages and automobiles on the wrong side of the road, before taking its current meaning. Jaywalking was coined as the automobile arrived in the street in the context of the conflict between pedestrian and automobiles, more specifically the nascent automobile industry.
A jughandle is a type of ramp or slip road that changes the way traffic turns left at an at-grade intersection. Instead of a standard left turn being made from the left lane, left-turning traffic uses a ramp on the right side of the road. In a standard forward jughandle or near-side jughandle, the ramp leaves before the intersection, and left-turning traffic turns left off of it rather than the through road; right turns are also made using the jughandle. In a reverse jughandle or far-side jughandle, the ramp leaves after the intersection, and left-turning traffic loops around to the right and merges with the crossroad before the intersection.
A junction is where two or more roads meet.
Turn on red is a principle of law permitting vehicles at a traffic light showing a red signal to turn into the direction of traffic nearer to them when the way is clear, without having to wait for a green signal.
In traffic engineering, there are regional and national variations in traffic light operation. This may be in the standard traffic light sequence or by the use of special signals.
An all-way stop – also known as a four-way stop – is a traffic management system which requires vehicles on all the approaches to a road intersection to stop at the intersection before proceeding through it. Designed for use at low traffic-volume locations, the arrangement is common in the United States, Canada, Mexico, South Africa, and Liberia, as well as in a number of, usually rural, locations in Australia where visibility on the junction approaches is particularly poor. The stop signs at such intersections may be supplemented with additional plates stating the number of approaches.
Road traffic collisions generally fall into one of five common types:
A HAWK beacon is a traffic control device used to stop road traffic and allow pedestrians to cross safely. It is officially known as a pedestrian hybrid beacon. The purpose of a HAWK beacon is to allow protected pedestrian crossings, stopping vehicular traffic only as needed. The HAWK beacon is a type of traffic control alternative to traffic control signals and/or where an intersection does not meet traffic signal warrants.
Road signs in South Korea are regulated by the Korean Road Traffic Authority.
Road signs in Canada may conform to the Manual of Uniform Traffic Control Devices for Canada (MUTCDC) by the Transportation Association of Canada (TAC) for use by Canadian jurisdictions. Although it serves a similar role to the MUTCD from the US Federal Highway Administration, it has been independently developed and has a number of key differences with its American counterpart, most notably the inclusion of bilingual (English/French) signage for jurisdictions such as New Brunswick with significant anglophone and francophone population, and a heavier reliance on symbols rather than text legends.
Terminology related to road transport—the transport of passengers or goods on paved routes between places—is diverse, with variation between dialects of English. There may also be regional differences within a single country, and some terms differ based on the side of the road traffic drives on. This glossary is an alphabetical listing of road transport terms.
A stroad is a type of street–road hybrid. Common in the United States and Canada, stroads are wide arterials that often provide access to strip malls, drive-throughs, and other automobile-oriented businesses. Stroads have been criticized by urban planners for their safety issues and inefficiencies. While streets serve as a destination and provide access to shops and residences at safe traffic speeds, and roads serve as a high-speed connection that can efficiently move traffic at high speed and volume, stroads are often expensive, inefficient, and dangerous.
Crosswalks in the United States and Canada are normally found at intersections, though sometimes may be found mid-block. Crosswalk installations must follow the regulations specified in the Manual on Uniform Traffic Control Devices (MUTCD). At signalized intersections, crosswalks may have pedestrian signals which display symbols to mandate when pedestrians may cross the street.