Traffic Operations and Management

Morning Commute with Competing Modes and DistributedDemand: User Equilibrium, System Optimum, and Pricing

Gonzales, Eric J.
Daganzo, Carlos F.
2011

The morning commute problem for a single bottleneck is extended to model mode choice in an urban area with time-dependent demand. This extension recognizes that street space is shared by cars and public transit. It is assumed that transit is operated independently of traffic conditions, and that when it is operated it consumes a fixed amount of space. As a first step, a single fixed-capacity bottleneck that can serve both cars and transit is studied. Commuters choose which mode to use and when to travel in order to minimize the generalized cost of their own trip. The transit agency chooses...

Rural Road Links: A Review on Current Research Projects & Initiatives Aimed at Reducing Vehicle Crash Fatalities on Rural Roads

Quiros, Lesliam
Shaver, Barrett
2003

Rural America accounts for a smaller and more dispersed portion of the nation’s population, yet it comprises a considerable portion of the transportation system. Rural areas account for approximately 83 percent of the land in the U.S and their roads account for 80 percent of the total U.S. road mileage and 40 percent of the vehicle miles traveled. Fatalities on rural roads surpass those in urban areas, even though urban areas are more densely populated and consequently, have a higher traffic flow. In 2001 alone, fatal crashes on rural areas accounted for 61 percent of all traffic...

Development and Application of the San Francisco Pedestrian Intersection Volume Model

Schneider, Robert J.
Henry, Todd
Mitman, Meghan F.
Stonehill, Laura
Koehler, Jesse
2013

The San Francisco pedestrian volume modeling process refined the methodology used to develop previous intersection-based models and incorporated variables that were tailored to estimate walking activity in the local urban context. The methodology included two main steps. First, manual and automated pedestrian counts were taken at a sample of 50 study intersections with a variety of characteristics. A series of factor adjustments were applied to produce an annual pedestrian crossing estimate at each intersection. Second, log-linear regression modeling was used to identify statistically-...

Providing Intersection Decision Support under Challenging Conditions

Shladover, Steven E.
VanderWerf, Joel
Ragland, David R.
2006

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...

Pedestrian Volume Modeling for Traffic Safety and Exposure Analysis:

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...

Intersection Decision Support Project: Taxonomy of Crossing-Path Crashes at Intersections Using GES 2000 Data

Ragland, David R.
Zabyshny, Aleksandr A.
2003

The Intersection Decision Support (IDS) Project is designed to reduce crossing-path (CP) crashes at intersections by providing crucial information to drivers that would help them avoid such crashes. Over the past decade, researchers have used the General Estimates System (GES, a representative sample of police-reported crashes in the US) and other data sources to develop a taxonomy of CP crashes and pre-crash scenarios as groundwork for crash-prevention efforts. The current study builds on and extends prior work by constructing a taxonomy of CP crashes using data from the 2000 GES and...

Safety and Other Impacts of Vehicle Impound Enforcement

Cooper, Douglas
Chira-Chavala, T.
Gillen, David
2002

California vehicle impound law took affect on January 1, 1995. The law allows a police officer to seize a vehicle operated by a person whose license is suspended or revoked or who has never been issued a license. The seized vehicle shall then be impounded for 30 days. In California, a driver must be stopped for some other infraction before his/her license can be checked. The purpose of this evaluation is to assess the impact of Upland's vehicle impound program on traffic safety (crashes and on-the-road behavior) and police department resources and operations.

Cost-Effectiveness of Traffic Safety Interventions in the United States

Vahindnia, Farnaz, PhD
Walsh, Julia PhD
2002

In order to demonstrate the results of all available studies on cost-effectiveness and traffic safety, and report them in a comparable format, we conducted a comprehensive review of the literature on the subject. Knowledge of cost-effective (CE) traffic safety programs that result in reduced motor vehicle crashes and fatalities is essential to city planners, managers, and police. METHOD: Using a systematic approach to literature review, the relevant literature has been identified through the use of electronic databases, hand searching of journals, scanning reference lists, and consultation...

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
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 findings...

Compliance, Congestion, and Social Equity: Tackling Critical Evacuation Challenges through the Sharing Economy, Joint Choice Modeling, and Regret Minimization

Wong, Stephen D.
2020

Evacuations are a primary transportation strategy to protect populations from natural and humanmade disasters. Recent evacuations, particularly from hurricanes and wildfires, have exposed three critical evacuation challenges: 1) persistent evacuation non-compliance to mandatory evacuation orders; 2) poor transportation response, leading to heavy congestion, slow evacuation clearance times, and high evacuee risk; and 3) minimal attention in ensuring all populations, especially those most vulnerable, have transportation and shelter. With ongoing climate change and increasing land development...