Public Works - Roads - Stop Signs
Effective STOP sign placement: Excerpts from the LTAP Technical Information Sheets #59 and #112
Improper Use of Stop Signs
Stop signs are one of the most common traffic signs and also one of the most often misused. A stop sign is intended to assign right-of-way at intersecting street locations. Commonly stop signs are placed in an effort to control speed on local streets. Many people believe that by forcing motorists to stop at each intersection overall speed on the adjacent street will decrease. However, studies show that stop signs only reduce speed immediately adjacent to the sign. Most drivers accelerate between intersections to make up for time lost at the stop sign. Engineering studies indicate that the installation of extra stop signs may cause additional problems such as more rear-end collisions, a redistribution of traffic onto side streets, and drivers ignoring the inappropriate stop signs.
Traffic patterns change over time as population increases or declines, new housing and business development occurs, trees and shrubs are trimmed, etc. As traffic patterns change, municipalities need to examine their traffic control at intersections to ensure that right-of-way is assigned properly and vehicles can navigate the roadway system safely and efficiently. Appropriate STOP sign installation, and proper location of them may reduce crashes and properly regulate traffic through an area.
Stop Sign Warrants
Stop signs should only be used where warranted because they cause substantial inconvenience to motorists. Motorists are inconvenienced because of lost time and expended fuel. A warrant is a guideline to determine the need for installation of a sign rather than absolute criteria, and their use tempered with professional judgment and local knowledge will result in effective implementation. For example, knowledge of the local road system will quickly identify problem accident areas that may be improved by proper sign placement. Local police officers or other municipal employees can collect the data to evaluate the following warrants. As outlined in the following warrants, vehicular volume counts, sight distance measurements, and possibly vehicle delay estimates are required to properly evaluate the warrants. Additionally a review of intersection geometry, adjacent roadway features and vehicle speeds through the area are necessary to accurately judge the placement of proposed stop signs. Stop sign warrants are outlined in the Pennsylvania Code TITLE 67
, Chapter 201, of the Pennsylvania Consolidated Statutes as follows:
Multiway Stop Intersections
- On a minor road at the entrance to an intersection where the application of the normal right-of-way rule creates unnecessary conflicts.
- On a street or highway entering a through highway.
- On the minor road at an unsignalized intersection in a signalized area.
- Where sight distance or the accident record indicate the need for control by stop signs.
- On a channelized right-turn roadway at a signalized intersection where:
Multiway stop intersections can also be an effective method of improving a hazardous location or controlling traffic congestion. Multiway stop warrants are also addressed in Publication 201. The following are warrants for multiway stop intersections:
Unwarranted Sign Locations
- Where traffic signals are urgently needed, the multiway stop is an interim measure that can be installed to control traffic while arrangements are being made for the signal installation.<.li>
- Where an accident problem is indicated by five or more accidents in a 12-month period of a type susceptible to correction by a multiway stop installation. Such accidents would include right-turn and left-turn collisions as well as right-angle collisions.
- Minimum traffic volume:
By following the appropriate steps prior to installing stop signs, their use and location may reduce accidents and properly regulate traffic through an area. Ignoring the warrants and improper signing creates dangerous conditions drivers and residents.
After a municipality has completed an engineering and traffic study to demonstrate that a change in assignment of the right-of-way is warranted (addition of STOP sign, removal or conversion of unwarranted four or two way stop control, change in traffic pattern, etc.), the Township must get approval from PennDOT to place the stop sign at the intersection; and, an appropriate ordinance must be passed or revised.
- The total vehicular volume entering the intersection from all approaches averages at least 500 vehicles per hour for any 8 hours of an average day, and
- The combined vehicular and pedestrian volume from the minor street or highway averages 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 maximum hour, but
- When the 85th percentile approach speed of the major street traffic exceeds 40 miles per hour, the minimum vehicular volume warrant in 70 percent of the requirements of clauses (A) and (B).
When the traffic volume
on either of the roadways is over 400 vehicles per day
and both of the following provisions are satisfied:
- The available corner sight distance for the driver on the minor road... is less than the appropriate stopping sight distance value for traffic on the major roadway...
- There is no practical method of improving the corner sight distance or reducing the speed limit to satisfy the minimum stopping sight distance...
- the traffic-control signals are not readily visible,
- the right-turn roadway does not have separate signals, and
- a yield sign is not appropriate.