February 25, 2005
STANDARDS GOVERNING USE OF STOP SIGNS BY MUNICIPALITIES
By: James J. Fazzalaro, Principal Analyst
You asked if there are federal guidelines or regulations that govern the criteria for putting up stop signs on municipal roads and, if so, if they are mandatory.
“STOP” signs and other types of signs, traffic lights, road markings, and any other device that is used to regulate, warn, or guide traffic are “traffic control devices.” Several decades ago, Congress determined that uniformity in the use and display of traffic control devices was an important federal interest and passed laws requiring the U.S. Department of Transportation to develop and adopt uniform standards for these devices. These standards currently exist in a document known as the Manual on Uniform Traffic Control Devices (MUTCD). The U.S. transportation secretary has decreed under authority granted by the Highway Safety Act of 1966 that traffic control devices on all streets and highway open to public travel in each state must be in “substantial conformance” with the standards issued and endorsed in the manual.
The manual contains standards and guidance for both the form and use of the various types of traffic control devices. The criteria the MUTCD identifies that should be considered when a decision is being made to use a particular type of traffic control device are also known as “warrants.” The standards and guidance in the MUTCD are universally accepted by traffic engineers and authorities at all levels, including municipalities, and are indicative of sound engineering judgment.
The MUTCD contains both general guidance for when STOP signs should be considered and more quantitative guidance for consideration when traffic officials are determining if signs should installed on more than one approach to an intersection, i.e., “multiway” stops. Typical of the general guidance are stipulations that STOP signs should not be used for speed control and that, in most cases, the street carrying the lowest volume of traffic should be stopped rather than the busier street. Typical of the quantitative guidance applicable to consideration of multiway stops are criteria accounting for accident history for certain types of accidents that are amenable to correction from STOP signs, average traffic volumes on the major street approaches, average combined volume (vehicles, pedestrians, and bicyclists) on the minor street approaches, and approach speed of traffic on the major street.
Pursuant to federal statutory and regulatory requirements, the federal highway administrator of the U.S. Department of Transportation adopted the Manual On Uniform Traffic Control Devices (23 USCA §§ 109(d), 114(a), 217, 315, and 402(a); 22 CFR 655, and 49 CFR 1.48 (b)(8), 1.48 (b)(33), and 1.48(c)(2)). The manual defines traffic control devices as all signs, signals, markings, and other devices used to regulate, warn, or guide traffic, placed on, over, or adjacent to a street, highway, pedestrian facility, or bikeway by authority of a public agency having jurisdiction. The manual is incorporated by reference in 23 CFR, Part 655, subpart f, and is recognized as the national standard for traffic control devices on all public roads open to travel in accordance with 23 USCA §§ 109(d) and 402(a).
In the MUTCD, the U.S. Secretary of Transportation, under authority granted by the Highway Safety Act of 1966, decreed that traffic control devices on all streets and highways open to public travel in each state must be in substantial conformance with the standards issued and endorsed by the Federal Highway Administration.
CGS § 14-298 establishes the State Traffic Commission within the Department of Transportation (DOT). It consists of the commissioners of Public Safety, Transportation, and Motor Vehicles. The law requires the commission, for the purpose of standardization and uniformity, to adopt and to publish regulations establishing a uniform system of traffic control signals, devices, signs, and markings consistent with state law for use upon the public highways.
State Traffic Commission regulations on the use of STOP signs specify that they: (1) should never be used on the through road of expressways; (2) should never be erected at intersections where traffic control signals are operating; (3) should normally be erected on the minor street to stop the lesser flow of traffic where two main highways intersect, unless traffic engineering studies justify a decision to install a sign on the major street; and (4) should not be used for speed control. The regulations also state that portable or part-time STOP signs should only be used for emergency purposes (Conn. Agency Regs. § 14-298-523). These regulations essentially mirror the general guidance provided by the MUTCD.
MUTCD GUIDANCE FOR STOP SIGN INSTALLATIONS
General Guidance for STOP Signs
In terms of general guidance, the MUTCD (§ 2B.05) states that STOP signs should be used if engineering judgment indicates that one or more of the following conditions exist:
● Intersection of a less important road with a main road where application of the normal right-of-way rule would not be expected to provide reasonable compliance with the law
● Street entering a through highway or street
● Unsignalized intersection in a signalized area
● High speeds, restricted view, or crash records indicate a need for control by the STOP sign
The MUTCD also states that STOP signs should not be used for speed control. This principle appears to be based on the results of several studies that have shown that when STOP signs have been installed for the purpose of controlling the speed of vehicles rather than to reduce the likelihood of vehicle conflicts at intersecting roads, the vehicle speeds between the sign installations typically increase over what they were prior to the signs being erected.
In addition, the MUTCD states that:
● STOP signs should be installed in a manner that minimizes the numbers of vehicles having to stop. At intersections where a full stop is not necessary at all times, consideration should be given to using less restrictive measures such as YIELD signs.
● Once a decision has been made to install two-way stop control, the decision regarding the appropriate street to stop should be made based on engineering judgment. In most cases, the street carrying the lowest volume of traffic should be stopped.
● A STOP sign should not be installed on the major street unless justified by a traffic engineering study.
The MUTCD lists several considerations that might influence the decision regarding the appropriate street upon which to install a STOP sign where two streets with relatively equal traffic volumes and/or characteristics intersect. These include:
● Stopping the direction that conflicts the most with established pedestrian crossing activity or school walking routes
● Stopping the direction that has obscured vision, dips, or bumps that already require drivers to use lower operating speeds
● Stopping the direction that has the longest distance of uninterrupted flow approaching the intersection
● Stopping the direction that has the best sight distance to conflicting traffic
Specific Guidance for Multiway Stop Applications
In addition to the general guidance and restrictions provided in Section 2B.05 of the MUTCD, it provides additional guidance for situations where a multiway, rather than a single stop will be used. It states that multiway stop control can be useful as a safety measure at intersections if certain conditions exist. Safety concerns associated with multiway stops include pedestrians, bicyclists, and all road users expecting other road users to stop. Multiway stop control is used where the volume of traffic on the intersection roads is approximately equal (§ 2B.07).
The guidance for multiway stops states that the decision to install a multiway stop should be based on an engineering study. The criteria, also known as warrants, that should be considered in such an engineering study are:
1. Where traffic control signals are justified, the multiway stop is an interim measure that can be installed quickly to control traffic where arrangements are being made for the installation of the traffic control signal.
2. A crash problem, as indicated by five or more reported crashes in a 12-month period that are susceptible to correction by a multiway stop installation. Such crashes include right- and left-turn collisions and right-angle collisions.
3. Minimum volumes— (a) The vehicular volume entering the intersection from the major street approaches (total of both approaches) averages at least 300 vehicles per hour for any eight hours of an average day, and (b) the combined vehicular, pedestrian, and bicycle volume entering the intersection from the minor street approaches (total of both approaches) averages at least 200 units per hour for the same eight hours, with an average delay to minor-street vehicular traffic of at least 30 seconds per vehicle during the highest hour, but (c) if the 85th percentile approach speed of the major-street traffic exceeds 65 kilometers or 40 miles per hour, the minimum vehicular volume warrants are 70% of the ones noted above.
Where no single criterion is satisfied, but where criteria 1, 2, 3(a), and 3(b) above are all satisfied to 80% of the minimum values, criterion 3(c) is excluded from the consideration. In traffic engineering, the 85th percentile speed is the speed at or below which 85% of the motor vehicles travel.
The engineering study may consider other criteria as well. These may include: (1) the need to control left-turn conflicts; (2) the need to control vehicle-pedestrian conflicts near locations that generate high pedestrian volumes; (3) locations where a road user, after stopping, cannot see conflicting traffic and is not able to reasonably safely negotiate the intersection unless conflicting cross traffic is also required to stop; and (4) an intersection of two residential neighborhood collector (through) streets of similar design and operating characteristics where multiway stop control would improve traffic operational characteristics of the intersection.