Guidleines for Removal of Traffic Control Devices in Rural Areas, October 2005

It is commonly regarded that the overuse of traffic control devices desensitizes drivers and leads to disrespect, especially for low-volume secondary roads with limited enforcement. The maintenance of traffic signs is also a tort liability concern, exacerbated by unnecessary signs. The Federal Highway Administration’s (FHWA) Manual on Uniform Traffic Control Devices (MUTCD) and the Institute of Transportation Engineer’s (ITE) Traffic Control Devices Handbook provide guidance for the implementation of STOP signs based on expected compliance with right-of-way rules, provision of through traffic flow, context (proximity to other controlled intersections), speed, sight distance, and crash history. The approach(es) to stop is left to engineering judgment and is usually dependent on traffic volume or functional class/continuity of system. Although presently being considered by the National Committee on Traffic Control Devices, traffic volume itself is not given as a criterion for implementation in the MUTCD. STOP signs have been installed at many locations for various reasons which no longer (or perhaps never) met engineering needs. If in fact the presence of STOP signs does not increase safety, removal should be considered. To date, however, no guidance exists for the removal of STOP signs at two-way stop-controlled intersections. The scope of this research is ultra-low-volume (< 150 daily entering vehicles) unpaved intersections in rural agricultural areas of Iowa, where each of the 99 counties may have as many as 300 or more STOP sign pairs. Overall safety performance is examined as a function of a county excessive use factor, developed specifically for this study and based on various volume ranges and terrain as a proxy for sight distance. Four conclusions are supported: (1) there is no statistical difference in the safety performance of ultra-low-volume stop-controlled and uncontrolled intersections for all drivers or for younger and older drivers (although interestingly, older drivers are underrepresented at both types of intersections); (2) compliance with stop control (as indicated by crash performance) does not appear to be affected by the use or excessive use of STOP signs, even when adjusted for volume and a sight distance proxy; (3) crash performance does not appear to be improved by the liberal use of stop control; (4) safety performance of uncontrolled intersections appears to decline relative to stop-controlled intersections above about 150 daily entering vehicles. Subject to adequate sight distance, traffic professionals may wish to consider removal of control below this threshold. The report concludes with a section on methods and legal considerations for safe removal of stop control.

Crash Rates and Crash Densities on Secondary Roads in Iowa by Functional Class 2001 – 2009, July 6, 2010

Crash Rates and Crash Densities on Secondary Roads in Iowa by Functional Class produced by the Iowa Department of Transportation.

Guidelines for Removal of Traffic Control Devices in Rural Areas, TR-527, 2005

It is commonly regarded that the overuse of traffic control devices desensitizes drivers and leads to disrespect, especially for low-volume secondary roads with limited enforcement. The maintenance of traffic signs is also a tort liability concern, exacerbated by unnecessary signs. The Federal Highway Administration’s (FHWA) Manual on Uniform Traffic Control Devices (MUTCD) and the Institute of Transportation Engineer’s (ITE) Traffic Control Devices Handbook provide guidance for the implementation of STOP signs based on expected compliance with right-of-way rules, provision of through traffic flow, context (proximity to other controlled intersections), speed, sight distance, and crash history. The approach(es) to stop is left to engineering judgment and is usually dependent on traffic volume or functional class/continuity of system. Although presently being considered by the National Committee on Traffic Control Devices, traffic volume itself is not given as a criterion for implementation in the MUTCD. STOP signs have been installed at many locations for various reasons which no longer (or perhaps never) met engineering needs. If in fact the presence of STOP signs does not increase safety, removal should be considered. To date, however, no guidance exists for the removal of STOP signs at two-way stop-controlled intersections. The scope of this research is ultra-low-volume (< 150 daily entering vehicles) unpaved intersections in rural agricultural areas of Iowa, where each of the 99 counties may have as many as 300 or more STOP sign pairs. Overall safety performance is examined as a function of a county excessive use factor, developed specifically for this study and based on various volume ranges and terrain as a proxy for sight distance. Four conclusions are supported: (1) there is no statistical difference in the safety performance of ultra-low-volume stop-controlled and uncontrolled intersections for all drivers or for younger and older drivers (although interestingly, older drivers are underrepresented at both types of intersections); (2) compliance with stop control (as indicated by crash performance) does not appear to be affected by the use or excessive use of STOP signs, even when adjusted for volume and a sight distance proxy; (3) crash performance does not appear to be improved by the liberal use of stop control; (4) safety performance of uncontrolled intersections appears to decline relative to stop-controlled intersections above about 150 daily entering vehicles. Subject to adequate sight distance, traffic professionals may wish to consider removal of control below this threshold. The report concludes with a section on methods and legal considerations for safe removal of stop control.

Iowa Roads and Streets Functional Classification Manual, 1970

This manual provides a set of procedural rules and regulations for use in functionally classifying all roads and streets in Iowa according to the character of service they are intended to provide. Functional classification is a requirement of House File 394 (Functional Highway Classification Bill) enacted by the 63rd General Assembly of the Iowa Legislature. Functional classification is defined in this Bill as: "The grouping of roads and streets into systems according to the character of service they will be expected to provide, and the assignment of jurisdiction over each class to the governmental unit having primary interest in each type of service."

Iowa Roads and Streets Functional Classification Manual, 1975

This manual provides a set of procedural rules and regulations for use in functionally classifying all roads and streets in Iowa according to the character of service they are intended to provide. Functional classification is a requirement of the 1973 Code of Iowa (Chapter 306) as amended by Senate File 1062 enacted by the 2nd session of the 65th General Assembly of Iowa. Functional classification is defined as the grouping of roads and streets into systems according to the character of service they will be expected to provide, and the assignment of jurisdiction over each class to the governmental unit having primary interest in each type of service. Stated objectives of the legislation are: "Functional classification will serve the legislator by providing an equitable basis for determination of proper source of tax support and providing for the assignment of financial resources to the governmental unit having responsibility for each class of service. Functional classification promotes the ability of the administrator to effectively prepare and carry out long range programs which reflect the transportation needs of the public." All roads and streets in legal existence will be classified. Instructions are also included in this manual for a continuous reporting to the Highway Commission of changes in classification and/or jurisdiction resulting from new construction, corporation line changes, relocations, and deletions. This continuous updating of records is absolutely essential for modern day transportation planning as it is the only possible way to monitor the status of existing road systems, and consequently determine adequacy and needs with accuracy.