Evaluation

Analysis of Wet Weather Related Collision Concentration Locations: Empirical Assessment of Continuous Risk Profile

Oh, Soonmi
Chung, Koohong
Ragland, David R.
Chan, Ching-Yao
2009

The objective of the study described in this paper is to identify common site features that may contribute to high collision rates under wet pavement conditions. To minimize falsely identified high collision concentration locations (HCCL) in evaluating factors contributing to high collision rate, this study accessed the magnitude of false positives (i.e., identifying sites for safety improvements that should not have been selected) by comparing HCCLs identified by the existing conventional sliding moving window approach with the ones identified by the Continuous Risk Profile (CRP)...

Safety Performance of High-Occupancy Vehicle (HOV) Facilities: Evaluation of HOV Lane Configurations in California

Jang, Kitae
Chung, Koohong
Ragland, David R.
Chan, Ching-Yao
2009

Collision data from High Occupancy Vehicle (HOV) facilities with two different types of access, continuous and limited, are examined in this paper. The findings show that HOV facilities with limited access offer no safety advantages over those with a continuous access. Compared with continuous access HOV lanes, a higher percentage of collisions was concentrated on limited access HOV lanes. Limited access HOV lanes also had higher collision rates. Findings from investigating the relationship between collision rates in HOV lanes with respect to shoulder width, length of access, and the...

Effects of Weather Variables on Pedestrian Volumes in Alameda County, California

Attaset, Vanvisa
Schneider, Robert J.
Arnold, Lindsay S.
Ragland, David R.
2010

Accurate estimates of pedestrian volume are important for analyzing pedestrian movement and safety; methods to estimate these volumes are continuously evolving and being improved. However, relatively little is known about the impact of weather conditions on pedestrian activity. This paper evaluates the effect of weather by including temperature, cloud cover, wind, and precipitation variables in a linear regression model of pedestrian volumes. Pedestrian volumes were collected over approximately one year using automated counters at 13 different locations in Alameda County, California...

A Methodology of Quantifying Precipitation Exposure for Wet-Weather Collisions and Evaluating Effectiveness of Open-Grade Asphalt Concrete as a CountermeasureWeather-related crashes represent a significant concern in roadway safety.

Chan, Ching-Yao
Jin, Eui-Jae
Oh, Soon Mi
Ragland, David R.
2010

Weather-related crashes represent a significant concern in roadway safety. Wet collisions often resulted in injuries or fatalities, at a ratio higher than collisions that occur in dry roadway conditions. Therefore, it is of strong interest to identify and manage the locations where collisions are prone to happen under wet pavement surface or adverse weather conditions. This paper introduces a method to estimate precipitation exposure of roadway segments by linking weather station data to collision database. Subsequently, the corresponding crash rate for a subject location is...

A Dynamic Congestion Pricing Strategy for High-Occupancy Toll Lanes

Jang, Kitae
Chung, Koohong
2010

High Occupancy Toll (HOT) lanes are emerging as a solution to address the underutilization of High Occupancy Vehicle (HOV) lanes and also means of generating revenue for state department of transportation. This paper proposes a method for dynamically determining the HOT toll price in response to the changes in traffic condition and documents procedures for estimating parameters needed for the proposed pricing strategies: revenue maximization and delay minimization. The proposed strategies have been applied to 14-miles of freeway segment in the San Francisco Bay Area, and the findings...

Evaluation of Traffic and Environment Effects on Skid Resistance in California

Oh, Soon Mi
Madanat, S M
Ragland, David R.
Chan, Ching-Yao
2010

Skid resistance is one of the important serviceability indicators related to safety on wet pavements. There is a need to manage skid resistance systematically to maintain the level of safety performance of roadway surfaces. This study focused on the development of a skid resistance deterioration model based on the analysis of skid data inventory collected in California. The California Department of Transportation (Caltrans) has collected skid resistance data across the complete state highway network over the past two decades using a standard locked-wheel skid trailer, ASTM E-274....

Performance Measures for Complete, Green Streets: A Proposal for Urban Arterials in California

Sanders, Rebecca L.
Macdonald, Elizabeth
Anderson, Alia
2010

The California Department of Transportation (Caltrans or “Department”) manages more than 15,000 miles of state highways, ranging in scale and function from local streets to interstate highways. Historically, Caltrans has been governed by the principles of highway engineering, which focus on providing mobility to motorized vehicles. Over the past decade, however, the Department has joined in a national movement to better incorporate non-motorized transportation and community-level outcomes into its transportation decision-making framework, embodied by the approach known as "Complete...

Property Damage Crash Equivalency Factors for Solving the Crash Frequency-Severity Dilemma: Case Study on South Korean Rural Roads

Oh, Jutaek
Washington, Simon
Lee, Dongmin
2010

Safety interventions (e.g. median barriers, photo enforcement) and road features (e.g. median type and width) can influence crash severities, crash frequencies, or both. Both dimensions—crash frequency and crash severity—are needed to obtain a full accounting of road safety. Extensive literature and common sense both dictate that all crashes are not ‘created’ equal—with fatalities costing society more than 1000 times the cost of property damage only crashes. Despite this glowing disparity, the profession has not unanimously embraced or successfully defended a non-arbitrary severity...

Single-Vehicle Fatal Crash Prediction for Two-Lane Rural Highways in the Southeastern United States

Zhu, Hong
Dixon, Karen K.
Washington, Simon
Jared, David M.
2010

The rural two-lane highway in the Southeastern United States is frequently associated with a disproportionate number of serious and fatal crashes and as such remains a focus of considerable safety research. The Georgia Department of Transportation spearheaded a regional fatal crash analysis to identify various safety performances on two-lane rural highways and offer guidance for identifying suitable countermeasures to mitigate fatal crashes. The fatal crash data used in this study were compiled from Alabama, Georgia, Mississippi, and South Carolina. The database, developed for an...

Experimental Evaluation of the Continuous Risk Profile (CRP) Approach to the Current Caltrans Methodology for High Collision Concentration Location Identification

Grembek, Offer
Kim, Kwangho
Kwon, Oh Hoon
Lee, Jinwoo
Liu, Haotian
Park, Min Ju
Washington, Simon
Ragland, David R.
Madanat, Samer M.
2012

This report evaluates the performance of Continuous Risk Profile (CRP) compared with the Sliding Window Method (SWM) and Peak Searching (PS) methods. These three network screening methods all require the same inputs: traffic collision data and Safety Performance Functions (SPFs), however, depending on how these input parameters are analyzed at the network screening level, the result of the analysis can vary significantly. Findings indicated that the CRP method produced far fewer false positives than SWM and PS. The false negative rates for CRP, SWM and PS were comparable. These...