All-way stop

An all-way stop is an intersection system used predominantly in the United States of America, Canada and South Africa where traffic approaching it from all directions is required to stop before proceeding through the intersection. Such intersections are most often found in the form of a '4-way stop', but may also sometimes be a '3-way stop' (either if one road ends there or if one street involved is one-way), or a '2-way stop' if both streets are one way or situated at right angles. Where five or more directions of traffic approach such an intersection 'all-way stop' is generally used. 'All-way stop' always implies that all approaches must stop, whereas 'N-way stop' does not necessarily imply this but always serves to indicate the number of approaches that do stop. A stop sign at an all-way stop does not need to have a supplemental plate but often does.

Operation

A motorist approaching an all-way stop is always required to come to a full stop. In most jurisdictions that use all-way stops, pedestrians always have priority at a crosswalk, even unmarked ones which exist at every intersection with approximately right angles as the logical continuations of the sidewalks. Bicyclists in some US jurisdictions, such as Idaho, may treat any stop sign as a yield sign. After a full-stop has been made, vehicles usually have the right-of-way to proceed through the intersection in the order that they have stopped at the intersection. In the USA if two or more vehicles arrive at approximately the same time the road user on the left yields to the user on their right , while in South Africa drivers must use common sense and gestures. Some areas have additional formal and informal rules which may or may not include special procedures for when all stop signs are approached simultaneously.

Application

In the USA the Federal Highway Administration's Manual on Uniform Traffic Control Devices defines the standards commonly used for the application of all-way stops. According to the MUTCD such applications should be based on a traffic engineering study. These intersections are often found (in accordance with the MUTCD) where roads with considerably equal traffic levels meet each other, but the overall level of traffic present at the intersection does not justify a traffic light and or or in a location where previously the right of way was unclear and concerns regarding the safety of users, especially pedestrians, exist. Other criteria might include a history of bad accidents in a given period, an interim measure preceding the placement of a traffic light, the presence of many pedestrians at any given time, high minimum traffic volume during a given period of a day, or where traffic is frequently delayed by turning conflicts. Additionally the MUTCD advocates the placement of all-way stops at intersections between through roads in residential areas if an engineering study can show that traffic flow would be optimized. Many jurisdictions, especially local ones in the USA arbitrarily place stop signs at many intersections, especially residential ones.

Where this intersection type is used a failed traffic light would usually be considered an all-way stop until police arrive or normal operation is restored. Alternatively, in some jurisdictions that use all-way stops, a failed traffic light is treated as an uncontrolled intersection. When an approach to an intersection is controlled by a red flashing light it is the equivalent of a stop sign in almost every US jurisdiction . When all approaches to an intersection are controlled in this way the rules for an all-way stop apply.

Worldwide Comparisons

Most countries outside North America, particularly in Europe, simply do not have intersections where all users have to stop whenever they are approached. As the most restrictive type of controlled intersection in North America, the all-way stop's equivalent is realized in a number of ways elsewhere. In countries where 'priority to the right' is observed as a default rule, the most restrictive type of intersection can be an uncontrolled one. It usually only occurs in conjunction with low-volume roads or as a traffic calming device that is similar in terms of desired effect, but not methodology to an all-way stop . An intersection type considered to be complementary (or alternative, depending on location) to the all-way stop and in fact used on six continents, is the roundabout. In particular the UK, amongst others, has adopted the roundabout instead of the all-way stop as the most restrictive type of intersection. There are a number of key differences in approach:

Slowing vs. Maintaining the Speed of Traffic

The roundabout permits arriving traffic to proceed without stopping provided there is no priority traffic on the junction (yield to traffic on the roundabout), whereas the all-way stop requires traffic to stop at the junction even when there is no other traffic in the vicinity at all. Therefore a side-effect of the all-way stop is to slow traffic, particularly useful in residential areas. The roundabout does not slow traffic unless caused by traffic congestion, and in uncongested situations a roundabout is even quicker to navigate than a traditional yield (Give Way) junction.

The frequent stopping of vehicles associated with all-way stops reduces their efficiency and increases wear in comparison to the relatively constant speed of a vehicle using roundabouts. This may help to explain the prominence of roundabouts in Europe, where fuel is typically more expensive than in North America.

Use in Restricted Spaces

The all-way stop works well for intersections that are small in size, whereas the roundabout requires room for a "central island reservation (typically circular) where no traffic is permitted, thus making it difficult to implement in smaller spaces. A typical all-way stop will be no bigger than a square the width of the approaching roads, whereas a roundabout must allow for this size plus the island reservation. The mini roundabout attempts to overcome this by using a painted circle which traffic is permitted to drive over.

Use in Larger Junctions

All-way stops are generally not used in junctions with more than four ways, due to the difficulty in judging who has next right of way. Traffic lights are used in bigger junctions. Roundabouts, on the other hand, scale well to larger intersections, and it is not unusual to see roundabouts with seven or eight roads in Europe. In busy areas, traffic lights can be used in combination with a roundabout, either permanently or only at peak periods, to control traffic coming on to, or rotating around the roundabout.

Cyclist and Pedestrian Safety

According to the Department for Transport, England, 10% of cycling accidents happen at roundabouts. However, roundabouts do not significantly contribute more or less than an average number of accidents overall, when compared to other junction types.As roundabouts become more common in the US the FHWA has attempted to mitigate pedestrian and cyclist safety concerns.

Except in larger traffic circles, pedestrians are generally not permitted to use the central island of a roundabout. To safely and perhaps legally continue through such intersections a pedestrian may be required take an even longer route than vehicular traffic to utilize pedestrian crossings. As the most restrictive type of intersection all-way stops are often considered the safest type of intersection for such users.

Driver Psychology

Roundabouts are considered by the British Automobile Association (AA) to pose "the biggest obstacle for learner drivers in the UK." Learner drivers can be confused by the constantly-moving nature of the roundabout.

Learner drivers also have difficulty correctly using All-way stops because of their complex rules, which often differ by location, and because they are observed with varying degrees of compliance. One uninformed or aggressive driver can easily disrupt the ideal flow through the intersection, which is not unlikely given the more complex rules for its users and the multitude of possible right-of-way of errors that can be made. Roundabouts do not suffer from such ambiguities. The only possible mistakes one can make in a roundabout are a failure to yield on entry or an unnecessary yield while in the roundabout. The simple rules and physics of a roundabout all but eliminate many of the dangerous movements associated with traditional crossroads; roundabouts command driver respect and are less complex than a all-way stops, but they may give drivers a false sense of security.

Nonetheless, stop signs at large are far more prominent in North America, notably the US, than in countries that do not use all-way stops. The colloquialism that 'familiarity breeds contempt' can help to explain why stop signs are almost universally (in terms of location, not users) disrespected in the US. For example: the criteria for the placement of an all-way stop might only take into account peak conditions, meaning a stop might only be necessary at peak times at an otherwise highly visible intersection. Legally obligated, but ostensibly unnecessary, frequent stopping can indirectly encourage faster and possibly illegal driving between stop signs. A driver traversing mostly roundabouts will, having likely not stopped, not have an incentive to speed and will be more receptive to a stop sign placed for actual safety needs, like because a yield/give way sign is insufficient. Despite the law, stop signs in the US are indeed violated in all manners, usually by simply not completely stopping, what is known as a 'rolling' or 'California' stop amongst other names.

See also

• Stop sign

References