Doug Heller, Commissioner, Springfield, PA

Multi-Way Stop Signs

by Mark Pohlmann
From the ITE District 4 Journal

Introduction

The determination of need and application of stop signs at unsignalized intersections has been a topic of discussion for many years. As professionals, we are many times faced with community and ‘political’ pressure to implement stop signs at ‘unwarranted’ intersections because there is a perception that a stop sign will improve safety for drivers and pedestrians. At other times, we, as engineers, can intuitively identify the need for the installation of a stop sign, even though traffic conditions show that a stop sign is not ‘warranted’ according to the guidelines of the Manual on Uniform Traffic Control Devices (MUTCD). This paper presents the problem as it relates to stop-sign warrants, presents results of research studies on the topic, summarize previous discussion on the topic and attempt to provide some practical guidance on the subject.

The Problem

Stop signs have been used for decades as a means to control traffic at intersections on rural highways, urban arterials or residential streets. On an engineering basis, there can be various reasons for installing a stop sign. However, many times engineering judgment is overridden by a perception that the installation of a stop sign will improve deficiencies in traffic operations and safety, thus leading to the installation of an ‘unwarranted’ stop sign.

The 2003 MUTCD provides guidance on the application of both two-way and multi-way stop sign control. However, this paper will limit itself to ‘warrants’ for the application of multi-way stops, as these are the only defined criteria with minimum operational thresholds to signify the justified application of a stop sign.

Literature Review

The 2003 MUTCD provides the following guidance for the installation of multi-way stop control:

“The decision to install multi-way stop control should be based on an engineering study.

The following criteria should be considered in the engineering study for a multi-way stop sign installation:

Where traffic control signals are justified, the multi-way stop is an interim measure that can be installed quickly to control traffic while arrangements are being made for the installation of the traffic control signal.
A crash problem, as indicated by 5 for more reported crashes in a 12-month period that are susceptible to correction by a multi-way stop installation. Such crashes include right- and left-turn collisions as well as right-angle collisions.
Minimum volumes:

The vehicular volume entering the intersection from the major street approaches (total of both approaches) averages at least 300 vehicles per hour for any 8 hours of an average day, and
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 8 hours, with an average delay to minor-street vehicular traffic of at least 30 seconds per vehicle during the highest hour, but
If the 85th-percentile approach speed of the major-street traffic exceeds 65 km/h or exceeds 40 mph, the minimum vehicular volume warrants are 70 percent of the above values.

Where no single criterion is satisfied, but where Criteria B, C.1, and C.2 are all satisfied to 80 percent of the minimum values. Criterion C.3 is excluded from this condition.

Other criteria that may be considered in an engineering study include:

The need to control left-turn conflicts;
The need to control vehicle/pedestrian conflicts near locations that generate high pedestrian volumes;
Locations where a road user, after stopping, cannot see conflicting traffic and is not able to reasonably safely negotiate the intersection unless cross traffic is also required to stop; and
An intersection of two residential neighborhood collector (through) streets of similar design and operating characteristics where multi-way stop control would improve traffic operational characteristics of the intersection.”

When these conditions exist, the multi-way stop control can be an effective safety measure at intersections. However, several studies have indicated that multi-way stops do not necessarily provide other perceived benefits to the area roadway network, such as reduced speeds. In addition, studies have also shown that ‘unwarranted’ multi-way stops potentially have detrimental effects to both traffic operational characteristics and safety for vehicles and pedestrians alike.

W. Martin Bretherton, Jr. conducted a review of over 70 technical papers on the subject of multi-way stops and their use as traffic control devices in residential areas. Although the MUTCD describes criteria that should be followed for the installation of multi-way stop control, Bretherton states that the MUTCD does not adequately describe problems associated with the application of ‘unwarranted’ multi-way stop signs such as liability, noise and pollution, enforcement and driver perception/reaction. The following is a summary of his findings as it relates to multi-way stop control:

Multi-way stops do not control speeds. Twenty-two papers were cited for these findings.
Stop compliance is poor at unwarranted multi-way stop signs. Unwarranted stop signs means they do not meet the warrants of the MUTCD. This is based on the drivers feeling that the signs have no traffic control purpose. There is little reason to yield the right-of -way because there are usually no vehicles on the minor street. Nineteen references found this to be their finding
Before-After studies show multi-way stop signs do not reduce speeds on residential streets. Nineteen references found this to be their finding.
Unwarranted multi-way stops increased speed some distance from intersections. The studies hypothesizing that motorists are making up the time they lost at the "unnecessary" stop sign. Fifteen references found this to be their finding.
Multi-way stop signs have high operating costs based on vehicle operating costs, vehicular travel times, fuel consumption and increased vehicle emissions. Fifteen references found this to be their finding.
Safety of pedestrians is decreased at unwarranted multi-way stops, especially small children. It seems that pedestrians expect vehicles to stop at the stop signs but many vehicles have gotten in the habit of running the "unnecessary" stop sign. Thirteen references found this to be their finding.
Citizens feel "safer" in communities "positively controlled" by stop signs. Positively controlled is meant to infer that the streets are controlled by unwarranted stop signs. Homeowners on the residential collector feel safer on a 'calmed' street. Seven references found this to be their finding. (Hypothesis twelve (below) lists five references that dispute the results of these studies.)
Speeding problems on residential streets are associated with "through" traffic. Frequently homeowners feel the problem is created by 'outsiders'. Many times the problem is the person complaining or their neighbor. Five references found this to be their finding.
Unwarranted multi-way stops may present potential liability problems for undocumented exceptions to accepted warrants. Local jurisdictions feel they may be incurring higher liability exposure by 'violating' the MUTCD. Many times the unwarranted stop signs are installed without a warrant study or some documentation. Cited by six references.
Stop signs increase noise in the vicinity of an intersection. The noise is created by the vehicle braking noise at the intersection and the cars accelerating up to speed. The noise is created by the engine exhaust, brake, tire and aerodynamic noises. Cited by five references.
Cost of installing multi-way stops are low but enforcement costs are prohibitive. Many communities do not have the resources to effectively enforce compliance with the stop signs. Five references found this to be their finding.
Stop signs do not significantly change safety of intersection. Stop signs are installed with the hope they will make the intersection and neighborhood safer. Cited by five references.

Hypothesis seven (above) lists seven references that dispute the results of these studies.
Unwarranted multi-way stops have been successfully removed with public support and result in improved compliance at justified stop signs. Cited by three references.
Unwarranted multi-way stops reduce accidents in cities with intersection sight distance problems and at intersections with parked cars that restrict sight distance. The stop signs are unwarranted based on volume and may not quite meet the accident threshold. Cited by three references.
Citizens feel stop signs should be installed at locations based on traffic engineering studies. Some homeowners realize the importance of installing 'needed' stop signs. Cited by two references.
Multi-way stops can reduce cut-through traffic volume if many intersections along the road are controlled by stop signs. If enough stop signs are installed on a residential or collector street motorists may go another way because of the inconvenience of having to start and stop at so many intersections. This includes the many drivers that will not stop but slowly 'cruise' through the stop signs. This driving behavior has been nicknamed the 'California cruise'. Cited by two references.
Placement of unwarranted stop signs in violation of Georgia State Law 32-6-50 (a) (b) (c). This study was conducted using Georgia law. Georgia law requires local governments to install all traffic controls devices in accordance with the MUTCD. This is probably similar to traffic signing laws in other states. Cited by two references.
Special police enforcement of multi-way stop signs has limited effectiveness. This has been called the 'hallo' effect. Drivers will obey the 'unreasonable' laws as long as a policeman is visible. Cited by two references.
District judge orders removal of stop signs not installed in compliance with city ordinance. Judges have ordered the removal of 'unnecessary' stop signs. The problem begins when the traffic engineer and/or elected officials are asked to consider their intersection a 'special case'. This creates a precedent and results in a proliferation of 'special case' all-way stop signs. Cited by two references.
Some jurisdictions have created warrants for multi-way stops that are easier to meet than MUTCD. The jurisdictions feel that the MUTCD warrants are too difficult to meet in residential areas. The reduced warrants are usually created to please elected officials. Cited by two references.
Citizens perceive stop signs are effective as speed control devices because traffic "slows" at stop sign. If everybody obeyed the traffic laws, stop signs would reduce speeds on residential streets. Cited by one reference.
Removal of multi-way stop signs does not change speeds but they are slightly lower without the stop signs. This study findings support the drivers behavior referenced in item #4, speed increases when unwarranted stop signs are installed. Speed decreases when the stop signs were removed! Cited by one reference.
Multi-way stops degrade air quality and increase CO, HC, and Nox. All the starting and stopping at the intersection is bad for air quality. Cited by one reference.

Economics of Multi-Way Stop Signs

Studies have found that installing unwarranted stop signs increases operating costs for the traveling public. The operating costs involve vehicle operating costs, costs for increased delay and travel time, cost to enforce signs, and costs for finesand increases in insurance premiums.

The total costs are as follows:

Operating Costs (1990)	$ 111,737/year ($.04291/Stop)
Delay & Travel Costs (1990)	$ 88,556 /year ($.03401/Stop)
Enforcement Costs (1990)	$ 837/year
Cost of Fines (19 per year)	$ 1,045/year
Cost of 2 stop signs (1990)	$ 280
Costs of increased insurance (1990)	$7,606/year
Total (1990)	$210,061/year/intersection

The cost to install two stops signs is $280. The cost to the traveling public is $210,061 (1990) per year in operating costs. This cost is based on about 8,000 vehicles entering the intersection per day.

Another study found that the average annual road user cost increased by $2,402.92 (1988 cost) per intersection when converting from two to four way stop signs for low volume intersections.

The 2003 MUTCD stresses that the ‘warrants’ for the application of multi-way stop control are simply criteria that should be considered in an engineering study. In fact, the current version of the MUTCD makes no mention of ‘warrants’ for multi-way stop sign installation. However, the criteria do provide a solid baseline for agencies and professionals to confidently recommend for/against the installation of multi-way stop signs on a consistent and uniform basis.

Some agencies, however, have viewed the criteria stated in the MUTCD as too rigid. Many have argued that the MUTCD criteria have high volume and crash thresholds that are virtually unattainable on many low-volume residential streets, which is where many of the requests are received. Therefore, some agencies have adopted their own criteria to either replace or supplement the criteria provided by the MUTCD, in order to address the unique circumstances of their community. Here are some examples:

Tempe, AZ

CRITERIA FOR MULTI-WAY STOPS ON RESIDENTIAL COLLECTOR STREETS — (NOT ON MID SECTION COLLECTORS)

Multi-way stops can be considered for installation on residential collector streets as part of the Traffic Management Program. A residential collector street is defined as a street that has residential frontage and collects traffic from other residential streets in a neighborhood ultimately intersecting with a mid section collector or arterial street. Multi-way stops can be considered for installation when the street being evaluated meets all of the following criteria.

Through street — minimum 1/2 mile in length
Width of street to not exceed 48'
Traffic volumes (less than 4,000ADT, total of highest 8 hours is at least 50% of ADT)
Cut through traffic (minimum of 20% of cut through traffic, in one direction during any one hour of the day)

City of Los Angeles, CA

Developed a unified policy for stop sign installation (see Appendix A).

City of Greensboro, NC

For all major/minor thoroughfares and intersections with AADT>3,500 vehicles per day, GDOT uses guidelines set forth in the current edition of the MUTCD

For any local and/or collector street and intersections with AADT<3,500 vehicles per day

The presence of any non-removable sight obstruction problem at the intersection may necessitate the need to immediately install a multi-way stop.
A speed limit of 25 MPH or 30 MPH must be in place before Multi-way stops will be considered along a non-stop street.
The vehicular volume from either approach on the non-stopped street should not exceed 5 times the vehicular volume from any one approach on the existing stopped street.
To prevent excessive stopping, an existing stop condition should not be located within 2 full block lengths (measured along the same side of the street when an offset or t-intersection is present) of a proposed stop condition. In instances of large block lengths, a proposed stop condition should not be located within 800 feet of an existing stop condition.
The longest leg of the side-street, or existing stopped street should extend at least 400 feet from the proposed multi-way intersection.
Geometric design features of the roadway such as horizontal/vertical alignment, on-street parking, street widths, sidewalks, and building setbacks may also be considered.
A positive petition of at least 67% of the property owners/residents along the existing non-stop street (as determined by GDOT) may be required, where appropriate. Those who sign the petition must agree to the placement of any needed stop signs, concrete islands, pavement markings, and advance-warning signs as determined by GDOT.

City of Toronto

Warrants for Implementing All-Way ‘Stop’ Sign Control

All-way ‘Stop’ sign control may be considered at intersections where at least one of the following of Warrants A or B is met, or other conditions identified in Warrants C or D is met:

COLLISIONS
There are an average of (see number below) collisions per year over three yearsof the type susceptible to correction by the use of all-way ‘Stop’ sign controls and where less restrictive measures* have been tried and found inadequate, with the major road classified as:
- minor arterial or collector (greater than 6000 AADT) — 4 collisions per year.
- collector (AADT less than or equal to 6000) — 3 collisions per year.
- local — 2 collisions per year.
VOLUMES
Roadway approaches have similar operating characteristics and the following conditions have been met:
Or
And
TRAFFIC CONTROL SIGNALS
As an interim measure where traffic control signals are technically warranted but cannot be implemented immediately.
REVERSAL OF INTERSECTION CONTROL
As a means of providing an introductory period to accustom drivers to a reversal of intersection control. Installation under this warrant shall be in conformance with Ontario MUTCD (1995), Section A2.11.04.

All-way ‘Stop’ sign control should not be used under the following conditions:
1. As a speed control device;
2. On roadways where progressive signal timing exists;
3. On roadways within urban areas having a posted speed limit in excess of 50 km/h;
4. At intersections that are offset, poorly defined or geometrically substandard;
5. On truck or bus routes, except in an industrial area or where two such routes cross;
6. As a means of deterring the movement of through traffic in a residential area; and
7. Where visibility of the sign is hampered by curves or grades, parked vehicles, and insufficient safe stopping distance exists.
All-way ‘Stop’ sign control can be used after special consideration in the following situations:
1. As the primary form of control to facilitate a request based solely on pedestrian crossing protection. This concern can usually be addressed by other means such as a school crossing, pedestrian crossover, or traffic control signal;
2. At intersections that are not roundabouts having less than three, or more than four, approaches;
3. At intersections with multi-lane approaches;
4. Where traffic would be required to stop on grades;
5. At intersections in close proximity to other traffic control devices controlling right-of-way; and
6. At intersections under certain traffic conditions, such as to control a conflicting traffic movement problem or address a motorist sight-line problem that cannot be addressed by other means, when supported by engineering judgment as being a useful safety measure.
* Note: In the case of Warrant A, less restrictive measures could include the removal of an obstruction or the prohibition of parking to improve sight lines; and/or the installation of warning signs, pavement markings and/or flashing beacons.

Arlington County, VA

Signal Installation:

Where traffic signals are warranted and urgently needed, a multiway stop sign is an interim measure that can be installed quickly to control traffic while arrangements are being made for the signal installation. (MUTCD)

Traffic Accidents:

An accident problem, as indicated by five or more reported accidents of a type susceptible of correction by a multiway stop sign installation in a 12-month period. Such accidents include right- and left-turn collisions, as well as right-angled collisions (MUTCD), or where the total number of reported accidents of a type susceptible of correction by a multiway stop sign within the most recent 12-month period is fewer than five, but where the number of accidents has averaged three or more per year over the past five years. ( Arlington County Warrant)

Minimum Traffic Volumes
For any street (MUTCD):

The total vehicular volume entering an intersection from all approaches must average at least 500 vehicles per hour for any eight hours of an average day, and the combined pedestrian, bicycle, and motor vehicle volume from the minor street must average 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 maximum hour.

For neighborhood streets (ArlingtonCounty Warrant):

The combined pedestrian, bicycle and motor vehicle volume entering the intersection from all approaches must average at least 300 units per hour for any eight hours of an average day, and

The combined pedestrian, bicycle and motor vehicle volume from the minor street must average at least 120 units per hour for the same eight hours.

Combination Warrant: ( Arlington County Warrant):

A multiway stop sign installation may be considered at intersections where at least two of the following are met:

The combined pedestrian, bicycle and motor vehicle volumes on each street approaching the intersection are no fewer than 1,000 units per day on each street, and have a volume distribution within the range of 50/50 to 60/40.

The total number of reported accidents of a type susceptible of correction by a multiway stop sign has averaged three or more per year for the past three years.

There is a significant restricted visibility problem, which limits the pedestrians’, bicyclists’, or motorists’ views of oncoming traffic to less than 200 feet, measured from the most distant decision point, that cannot be corrected by normal maintenance activity (vegetation trimming) or the installation of parking restrictions.

Crossing Safety Warrant: ( Arlington County Warrant):

A multiway stop sign installation may be considered, after an engineering study, in exceptional cases where other measures have not been effective or are judged not feasible, in regulating crossing safety for pedestrian, bicyclists, or motorists. An engineering study includes, but is not limited to, the consideration of the following factors: reported accidents; pedestrian, bicycle and motor vehicle volumes; pedestrian, bicyclist and motor vehicle patterns; crossings near schools and parks; existing roadway conditions and geometry; and operating characteristics.

Unimpeded Travel Distance Warrant on Neighborhood Streets: ( Arlington County Warrant):

Following an engineering study finding that overall intersection safety would not decrease, if the unimpeded travel distance on a neighborhood street exceeds 1500 feet and there is a minor street along it with a pedestrian, bicycle and motor vehicle volume exceeding 500 units per day, a multiway stop sign installation may be installed at the most appropriate minor street intersection location. The unimpeded distance is that which is free of measures that assign right-of-way (signals, stop signs, and yield signs) and of physical measures (e.g., traffic circles) to influence speeds.

The commonality among these policy examples is the goal of developing a policy which can be administered in a very uniform and consistent manner. The policies set precedence for responding to requests for multi-way stop signs, which helps limit the liability risk inherent in operating and maintaining public facilities.

Conclusions

Through the extensive literature review conducted by W. Martin Bretherton, Jr., the current MUTCD should be the underlining criteria for justifying the installation of multi-way stop control at unsignalized intersections. In addition, it is further stressed that a thorough engineering study that properly documents traffic conditions and adequately justifies the installation of multi-way stop control be conducted. Research has shown that multi-way stop control has negative effects to safety and efficient traffic operation at intersections where conditions do not exist to ‘warrant’ installation.

Some jurisdictions have developed their own unique criteria for determining the need for multi-way stop control, which may either replace or supplement the criteria provided in the MUTCD. Some examples are the City of Los Angeles, CA, the City of Greensboro, NC and the City of Arlington, VA. These policies were created to accommodate the unique circumstances of the community, while maintaining a consistent and uniform practice for determining the installation of multi-way stop control.

Sources

www.city.toronto.on.ca/legdocs/2002/agendas/council/cc020730/wks9rpt/cl010.pdf
www.co.arlington.va.us/cmo/issues/multiway.htm
www.city.toronto.on.ca/legdocs/2001/agendas/committees/cp/cp010618/it004.pdf
Fisher, J.E., Stop Sign Warrants: Bridging the Philosophical Divide, ITE 2001 Annual Meeting and Exhibit, Location: Chicago, Illinois, USA, Pulication Date: 08/00/2001

About the Author

Mark D. Pohlmann, P.E., PTOE – Mark earned his bachelor’s and master’s degree in civil engineering, with emphasis in transportation/urban systems engineering, from Washington University in St. Louis, MO. After graduating, Mark joined The Schemmer Associates Inc. in July 1999 and earned the title of Senior Traffic Engineer. He has recently been promoted within the firm to Transportation Manager-Iowa and has been relocated from Lincoln, NE to Council Bluffs, IA. Mark has extensive experience in performing many types of studies for both public and private clients, including traffic impact studies, development of optimized signal timing plans, roundabout analysis, and traffic signal design. He is a registered Professional Engineer in Iowa, Nebraska, and South Dakota and is also a certified Professional Traffic Operations Engineer.

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