Data collection

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

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

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.

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

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

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

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...

Missed or Delayed Medical Care Appointments by Older Users of Nonemergency Medical Transportation Services

MacLeod, Kara E.
Ragland, David R.
Prohaska, Thomas R.
Irmiter, Cheryl
Satariano, William
Leary, Mary A.

Non-emergency medical transportation (NEMT) can prevent emergency care as a result of delayed or missed medical appointments. Medicaid provides NEMT for low income individuals who have no other means of transportation and this is a critical component of the health care delivery system. This study examined cancelled trips in Medicaid adults age 65+ to explore whether barriers persist for a growing segment of the population who face particular challenges of age-related declines in health and function. Multivariate logistic regression analyses were conducted using transportation...

Observational Study of Cell Phone and Texting Use Among California Drivers 2015 and Comparison to 2011 through 2014 Data

Cooper, Jill F.
Ragland, David R.
Ewald, Katrin
Wasserman, Lisa
Murphy, Christopher J.

In the 2015 observations, the majority of drivers (73.0%) drove alone, and 22.0% had one passenger in the car. The increase of drivers driving alone since 2014 (4.8%) and the decrease (3.5%) of drivers driving with one passenger is significant (Table 13).

Complete Streets: From Policy to Practice in the San Francisco Bay Area

Pande, Swati
Martinez, Martin

This paper describes how regional funding guidelines can affect local adoption of Complete Streets projects. The Metropolitan Transportation Commission (MTC), the regional Metropolitan Planning Organization for the nine-county Bay Area region in California, has developed a funding approach called the One Bay Area Grant (OBAG) for the allocation of funds for the 2012-2016 Congestion Mitigation and Air Quality (CMAQ) and Surface Transportation Program (STP) across the Bay Area. Each jurisdiction receiving funding through OBAG was required to demonstrate compliance with Complete Streets (CS)...

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

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...

Impact of Traffic States on Freeway Collision Frequency

Yeo, Hwasoo
Jang, Kitae
Skabardonis, Alexander

Freeway collisions are thought to be affected by traffic states. To reduce the number of collisions, the study to reveal how the traffic states influence collisions are required. Therefore, the purpose of the paper is to suggest a method to relate traffic states to collision frequency in freeway. We first defined section- based traffic phases showing traffic state of a section using upstream and downstream traffic states: free flow (FF), back of queue (BQ), bottleneck front (BN) and congestion (CT). Secondly, by integrating freeway collision data and traffic data from the California PeMS...