What is the purpose of a stop sign?
Generally, stop signs are placed to prevent crashes where there might be a question about who should have the right of way. When considering stop sign placement, how a stop sign effects the overall safety and needs of the community is closely examined. For example, stop signs in one location could effect traffic on nearby streets. Drivers may seek new routes to avoid stop signs, which can lead to new traffic problems in adjacent neighborhoods.
In some instances, putting a stop sign on one street can foster higher speeds on the intersecting streets. The final decision to install a stop sign is made after City traffic engineers consider the traffic flow and volume, the configuration of the intersection, crash reports and the overall safety of the neighborhood.
Do stop signs really reduce speeding?
Stop signs may often seem like a good solution to neighborhood speeding, but traffic studies and experience show that using stop signs to control speeding doesn’t necessarily work. When stop signs are installed to slow down speeders, drivers may actually increase their speed between signs to compensate for the time they lost by stopping. Some drivers tend to accelerate rapidly after a stop, possibly creating an even more dangerous situation. In fact, most drivers reach their top speed within 100 feet of a stop sign. Traffic studies have shown that too many stop signs could cause motorists to ignore the right of way rule, and some may simply choose to ignore the stop sign. And, while you wouldn’t expect this, more stop signs in a neighborhood can actually result in higher levels of pollution and noise.
Criteria for two-way stop signs
Stop signs are installed at intersections where motorists cannot safely apply the right of way rule and crashes sometimes occur as a result. City traffic engineers consider a number of street characteristics when determining effective placement of a stop sign as a traffic control device.
Criteria they look for include:
- An intersection where a road with a lower volume intersects with a higher volume road, such as a collector or an arterial, and the normal right-ofway rule is not expected to provide reasonable compliance with the law.
- An unsignalized intersection in a signalized area.
- A restricted view.
- Crash records that indicate a need for control by a stop sign.
- An area of local streets bounded by through-streets where the majority of intersections are controlled by stop signs. When that is the case, all remaining uncontrolled intersections may be considered for signage as a part of a comprehensive, area-wide “Neighborhood Stop Plan.” (See neighborhood stop plan)
Criteria for four-way or all-way stops
In most cases, a two-way stop sign is sufficient to define who has the right of way. A four-way or all-way stop is considered only when an intersection with a two-way stop is the site of numerous crashes or traffic congestion problems.
Four-way stop signs are used:
- In locations where traffic signals are needed. Four-way or all-way stops may be used as an interim measure.
- When there has been a history of crash problems in a local street
- Five or more reported crashes in a two-year period and the crashes would likely have been prevented by an all-way stop
- On through streets, where within a two-year period the intersection had at least 1.5 crashes per million vehicles entering the intersection, and the crashes would likely have been prevented by all-way stops
- When the intersection meets a traffic volume minimum
- The vehicular volume entering the intersection from the major street approaches (total of both approaches) an average of at least 300 vehicles per hour for any 8 hours of an average day, and ƒthe combined vehicular, pedestrian, and bicycle volume entering the intersection from the minor street approaches (total of both approaches) an average of at least 200 units per hour for the same 8 hours, with an average delay to minor-street vehicular traffic of at least 30 seconds per vehicle during the highest hour; but ƒif the 85th-percentile approach speed of the major-street traffic exceeds 50 mph, the minimum vehicular volume warrants are 70% of the above values
What is a neighborhood stop plan?
The neighborhood stop plan is a more systematic approach to stop sign installation that entails examining an area and establishing stop controlled intersections in an alternating pattern throughout the area.