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Federal Highway Administration Research and Technology
Coordinating, Developing, and Delivering Highway Transportation Innovations

This report is an archived publication and may contain dated technical, contact, and link information
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Publication Number:  FHWA-HRT-14-020    Date:  January 2015
Publication Number: FHWA-HRT-14-020
Date: January 2015


Factors Influencing Operating Speeds and Safety on Rural and Suburban Roads


The research team identified several treatments for possible field evaluations during this study and based the following list of possible treatments for field evaluations on findings of the literature review and State outreach efforts:

The FHWA technical review panel for this project organized these nine treatments into three groups: 1) treatments it has a high interest in evaluating, 2) treatments it has only a moderate interest in evaluating, and 3) treatments it has only a low interest in evaluating.

The panel’s highest interest treatments were the following, in no particular order:

Its moderate interest treatments were the following, in no particular order:

The panel’s low interest treatments were the following, in no particular order:

The research team also assessed treatments based on State and local agency interests and their willingness to install them for this study purpose. For example, converging chevron pavement markings were not included in a treatment evaluation because of a lack of existing treatment locations on rural and suburban highways and the reluctance of agencies to install and maintain this treatment for the purposes of this study.

Based on feedback from FHWA, the current study completed the following evaluations:

It should be noted that the FHWA selection of treatments to study as part of this effort is not necessarily correlated with magnitudes of expected speed reductions.


In addition to the operational and safety evaluations completed for the current study, the research team also examined State and local transportation agency police accident reports and completed

a speeding-related, clinical crash analysis. The purpose of this assessment was to determine which speeding-related crash characteristics (e.g., driver age, gender, degree of familiarity with the crash location, weather conditions, and other factors) may influence speeding-related crash occurrence. This detailed analysis was intended to provide insights into crash causation that could not otherwise be determined by analyzing only electronically coded data. To perform this evaluation, the research team reviewed police reports from the following jurisdictions:

The analysis considered speeding-related crashes that occurred in rural and small urban areas (population fewer than 50,000 persons), in the years 2004 to 2008. Most local transportation agencies that provided hardcopy speeding-related crash reports did not provide data concerning the total number of crashes occurring within the jurisdiction during the analysis period. Therefore, the proportion of the speeding-related crashes in the total crashes was not known.

The research team used the coding provided on the police accident report to identify speeding- related crashes. The following three driver actions, either singly or in combination, were identified as speed-related crashes:

When reviewing the hardcopy police accident reports, the research team not only assessed the coding provided by the investigating officer, but also reviewed the narrative and diagram of the crash location.

The research team identified a total of 1,895 nonintersection speeding-related crashes in the nine counties (four States) listed above; the team then excluded crashes with the following characteristics:

These precipitating events in these crashes might not necessarily be attributable to speeding; consequently, driver impairment, poor weather conditions, differences in vehicle size and weight, and unexpected animal crossings were considered as factors not necessarily associated with speeding. After excluding these four crash types, 586 (30.9 percent) crashes met the speeding-related crash criteria described above.

The general findings from the clinical speeding-related crash analysis indicate the following:

The findings from the clinical crash analysis suggest that inexperienced drivers are more likely to be involved in speeding-related crashes on curved alignments when compared with tangent alignments. In general, however, speeding-related crashes appear more likely on curved road segments when compared with tangent roadway segments. Speeding-related crashes on curves appear overrepresented at night when compared with daytime speeding-related crashes.


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