Training and education

Modeling Bicycle Passing Maneuvers on Multilane Separated Bicycle Paths

Li, Zhibin
Wang, Wei
Liu, Pan
Bigham, John M.
Ragland, David R.
2012

Bicycle passing maneuvers represent interferences between bicycle travelers and are important operational attributes of bicycle traffic. The number of bicycle passing maneuvers has been used to evaluate the level of service (LOS) of off-street bicycle facilities. The primary objectives of this paper are to propose a method to model bicycle passing maneuvers on multilane bicycle paths with heavy bicycle traffic and explore the characteristics of those passes. The authors classified bicycle passing maneuvers into free, adjacent, and delayed passes according to the lateral distance...

Estimating Pedestrian Accident Exposure: Automated Pedestrian Counting Devices Report

Bu, Fanping
Greene-Roesel, Ryan
Diogenes, Mara Chagas
Ragland, David R.
2007

Automated methods are commonly used to count motorized vehicles, but are not frequently used to count pedestrians. This is because the automated technologies available to count pedestrians are not very developed, and their effectiveness has not been widely researched. Moreover, most automated methods are used primarily for the purpose of detecting, rather than counting, pedestrians (Dharmaraju et al., 2001; Noyce and Dharmaraju, 2002; Noyce et al., 2006). Automated pedestrian counting technologies are attractive because they have the potential to reduce the labor costs associated with...

Estimating Pedestrian Accident Exposure: Protocol Report

Greene-Roesel, Ryan
Diogenes, Mara Chagas
Ragland, David R.
2007

Walking is a healthful, environmentally benign form of travel, and is the most basic form of human mobility. Walking trips account for more than 8 percent of all trips taken in California, making walking the second most commonly used mode of travel after the personal automobile (Caltrans, 2002). In addition, many trips made by vehicle or public transit begin and end with walking.

In spite of the importance and benefits of walking, pedestrians suffer a disproportionate share of the harm of traffic incidents in California. As noted above...

Using Time-Based Metrics to Compare Crash Risk Across Modes and Locations

Guler, S. Ilgin
Grembek, Offer
Ragland, David R.
2012

The objective of this work is to identify better metrics of exposure when comparing traffic crash risk across modes or across locations. We propose that total time travelled should be used for road user exposure to crash risk. The idea behind this is that travel time reflects the differences in speeds across different modes and hence should be used as the basic exposure metric from which crash risk based on other metrics, such as travel distance, can easily be derived. We also propose that when comparing crash risk of different modes across different locations the time-based mode share...

Recommendations to Improve Pedestrian Safety in the Town of Paradise

Dang, Tony
Alfsen, Wendy
2013

In response to the recent death of a Paradise youth who was struck on Skyway Road, the Town of Paradise invited California WALKS to facilitate a workshop providing community residents, Town staff members, and other professionals with an overview of pedestrian safety best practices, to conduct a walkability assessment of areas near the downtown core, and to lead small group discussions to develop specific recommendations for Town Council to improve the safety and walkability of Paradise. This report summarizes overall walkability and pedestrian safety observations of downtown Paradise, as...

Pedestrian Volume Modeling for Traffic Safety and Exposure Analysis: The Case of Boston, Massachusetts

Raford, Noah
Ragland, David R.
2005

This paper examines three types of pedestrian volume models in light of their usefulness for estimating pedestrian exposure for pedestrian safety research. The need for pedestrian flow data as part of pedestrian exposure and safety analysis is outlined, and the background of each type of model is discussed. It then selects the space syntax network analysis model to estimate pedestrian volumes for the city of Boston, Massachusetts. It was found that the model was able to accurately predict pedestrian flows (r-squared 0.81, p-value < 0.0001) after incorporating distance to transit stops...

Gap acceptance for vehicles turning left across on-coming traffic: Implications for Intersection Decision Support design

Ragland, David R.
Arroyo, Sofia
Shladover, Steven E.
Misener, James A.
Chan, Ching-Yao
2005

A left-turning vehicle (Subject Vehicle, SV) attempting to cross the path of an oncoming vehicle (Principal Other Vehicle, POV) at an intersection typically does not have the right of way. The main task of the SV driver is to find an adequate opportunity in opposing traffic to initiate the left-turn maneuver. To reduce the probability of a conflict, warning systems, such as Intersection Decision Support (IDS) systems, are being developed. These systems alert drivers of SV vehicles attempting to negotiate a left turnabout traffic approaching from the opposite direction. The current...

Providing Intersection Decision Support under Challenging Conditions

Shladover, Steven E.
VanderWerf, Joel
Ragland, David R.
2005

This paper describes the results of simulation studies to determine how effectively left-turning drivers can be alerted to imminent conflicts with opposing traffic under difficult operating conditions and with limited detector capabilities. These conditions include approaching vehicles changing speed in locations that are not covered by detectors and detectors that may only be able to detect vehicle presence, but not speed. In cases without direct speed detection, one may try to rely on historical speed statistics to estimate the speed of approaching traffic, but unless the approach speeds...

The Continuing Debate about Safety in Numbers—Data from Oakland, CA

Geyer, Judy A.
Raford, Noah
Ragland, David R.
Pham, Trinh
2006

The primary objective of this paper is to review the appropriate use of ratio variables in the study of pedestrian injury exposure. We provide a discussion that rejects the assumption that the relationship between a random variable (e.g., a population X) and a ratio (e.g., injury or disease per population Y/X) is necessarily negative. In the study of pedestrian risk, the null hypothesis is that pedestrian injury risk is constant with respect to pedestrian volume. This study employs a unique data set containing the number of pedestrian collisions, average annual pedestrian volume, average...

High Collision Concentration Location: Table C Evaluation and Recommendations

Ragland, David R.
Chan, Ching-Yao
2007

This report describes the research work that was conducted under PATH Task Order 5215 and its extension Task Order 6215, “Methods for Identifying High-Concentration Collision Locations (HCCL).” The subject matter is related to regularly published Caltrans reports, so-called Table C, that are used to screen for and investigate locations within the California State Highway System that have collision frequencies significantly greater than the base or expected numbers when compared to other locations. The accuracy and reliability of such reports are critical as Table C is the basis for follow-...