Technical Resources

Transportation Safety Resources

The following is a listing of the most recent publications for this topic.

An Explanation of Mats Järlström's Extended Kinematic Equation
Since the yellow indication was first added to traffic signals in 1920, the proper interval duration has been robustly debated.1 Seemingly, the timing of the yellow indication appears straightforward. However, determining the illumination interval is quite intricate since it is part of a complex system of physical and human-made laws, technology, and human behavior that all must operate compatibly.
Feb 26, 2020
An Extended Yellow Change Interval Solution Derived from GHM's Critical Distance
The critical distance is the foundation to Gazis, Herman and Maradudin's (GHM) universally adopted minimum yellow traffic signal timing solution presented in their 1960 paper, "The Problem of the Amber Signal Light in Traffic Flow" [1]. However, GHM's (permissive [2]) minimum yellow signal duration is limited in its application since they only accounted for vehicles moving at constant velocity traversing a minimum safe and comfortable stopping distance referenced a level intersection's stopping line, aka GHM's critical distance.
Feb 26, 2020
Guidelines for Determining Traffic Signal Change and Clearance Intervals
ITE has concluded a years-long effort to issue guidance on yellow change and red clearance intervals for signalized intersections. The final version of the Recommended Practice Guidelines for Determining Traffic Signal Change and Clearance Intervals (RP-040B) has been adopted by the ITE International Board of Direction and is now available.1
Feb 26, 2020
Press Release: ITE Releases Recommended Practice for Traffic Signal Change and Clearance Intervals
The Institute of Transportation Engineers (ITE) has issued guidance on yellow change and red clearance intervals for signalized intersections. The recommended practice -- Guidelines for Determining Traffic Signal Change and Clearance Intervals -- has been adopted by the ITE International Board of Direction and is now available for purchase.
Feb 26, 2020
Traffic Signal Change and Clearance Intervals: Research Still Needed!
Yellow change and red clearance intervals have been a topic of research for at least the last 60 years. It would be easy to assume that we now know all we need to know about the subject and that the remaining challenge is merely to put what we know into practice. But there is still much about driver behavior at intersections during traffic signal changes that we don't know with certainty or completely understand. During the development of the ITE Guidelines for Determining Traffic Signal Change and Clearance Intervals Recommended Practice, current knowledge, research, and practice in this area was documented, but the following 11 areas of interest were identified where additional study or new research is needed to expand the body of knowledge. Research in these areas would be useful in further refining the concepts and procedures in the ITE Recommended Practice.
Feb 26, 2020
Yellow Change Intervals for Turning Movements Using Basic Kinematic Principles
This discussion will review various models of drivers approaching an intersection in both through and turning lanes and what yellow change interval may be necessary in those situations. It is an extension of the work of Gazis, Herman, and Maradudin's (GHM) in their seminal 1960 paper, "The Problem of the Amber Signal Light in Traffic Flow". GHM proposed the basic protocol used today for setting a minimum yellow change interval for through movements that would provide a motorist with a solvable solution to the stop or go problem encountered when the yellow signal is illuminated.
Feb 26, 2020
Impacts of Red-Light Cameras on Intersection Safety: A Bayesian Hierarchical Spatial Model
Intersection safety is one of the most significant issues cities face in managing traffic safety. It has been shown that red light running (RLR) is an important contributing factor for crashes at signalized intersections. According to the Insurance Institute of Highway Safety (IIHS), red-light runners encompass about 800 deaths and 137,000 injuries annually in the United States. Introducing enforcement as an effective way to change driver behavior at intersections and consequently to prevent RLR has incentivized cities to implement automated red light camera (RLC) programs. In a recent study, the safety at intersections with RLC systems in 57 cities was compared to that of 33 cities without such a program. The comparison showed that the ratio of RLR fatal crashes per capita to all intersection-related fatal crashes improved by 21 percent after the RLC program implementation.
Dec 2, 2019
Road Safety Audits/Inspections: A Promise Unfulfilled
When the techniques and procedures of road safety audits and road safety inspections were first introduced in the United Kingdom and subsequently in Australia and New Zealand towards the end of the 20th century, many saw these as a potential tool of great promise, one that would be a tremendous aid in improving the safety of roads in developing countries. Today, more than 20 years later, that promise is still not fulfilled.
Nov 1, 2019
USDOT Highway-Rail Crossing Handbook, Third Edition
Railroad Grade Crossings - Safe as They Can Be?
Jul 24, 2019
Evolving to ATSPM for Safety and Mobility within Small Communities
Rural Traffic and Safety Management
Jul 23, 2019
Safety Improvement Projects in Austin, Texas – A Success Story
Vision Zero Program Implementation
Jul 23, 2019
Using Drones to Collect Speed Data: A Novel Approach
Rural Traffic and Safety Management
Jul 23, 2019
Connected Responder: A Business Case Primer for Connected Vehicles for Emergency Responders
Enhancing Public Safety Through Advances in Responder Technology
Jul 22, 2019
New Road Safety Professional Certification Now Available!
The Transportation Professional Certification Board (TPCB), in collaboration with a wide array of transportation and safety-related organizations in the United States and Canada, announced the availability of a new Road Safety Professional (RSP) Certification® last year. The certification became available on October 1, 2018. The goals of the RSP certifications are to recognize road safety as a profession, to establish a recognized level of practice and knowledge, and to incentivize safety education.
Jul 1, 2019
Promoting Bike Safety through Safe Road Design
Bicycling is an efficient, enjoyable, social, and environmentally friendly form of transportation that is growing in popularity across North America. While research shows that a large portion of the population is interested in cycling, many are deterred from it due to the risk or fear of being involved in a collision. As transportation practitioners play a key role in mitigating collision risk on the road network, and given that June is National Safety Month, this article highlights some of the fundamental safety aspects to consider when planning and designing bicycle facilities.
Jun 1, 2019
Unsafe Driver Glances at Roadside Unmanned Aerial System Operations
Recent technological advances have made unmanned aerial systems (UASs)--commonly referred to as drones--smaller, more affordable, and more available for civilian operations. As UASs become more ubiquitous in applications for industry, agriculture, and transportation, they will inevitably interact with existing roadway infrastructure. Current commercial, governmental, and research operations are subject to Part 107 of Federal Aviation Administration (FAA) regulations. This policy regulates commercial (non-hobby) UAS use, including pilot responsibilities, operational limitations, and aircraft requirements. The portion of these rules related to roadway infrastructure (Part 107.39) does not allow pilots to operate a UAS directly over moving vehicles. In addition, some states have passed laws related to limiting UAS operations near enclosed critical infrastructure facilities (e.g., water treatment plants). Additional legislation allows for law enforcement and other state government agencies to operate UASs. While not an exhaustive list, such legislation is indicative of state efforts to adapt to this disruptive technology as the legal landscape continues to evolve.
Jun 1, 2019
Canada and the Safe Systems Approach to Road Safety
In Canada, more than 235,000 people have been killed in motor vehicle crashes since 1950. In the last 10 years, approximately 187,000 people have been hospitalized from traffic crashes.1 No recent progress has been made in reducing fatalities and major injuries to pedestrians and cyclists, and the overall topic of road deaths is not receiving the political traction or public discussion that is needed. Researchers Johnston, Muir, and Howard found that the majority of serious trauma from road crashes does not involve a driver purposefully breaking an overt law, but ordinary people doing ordinary things.2 But what are the solutions to the problem? To achieve meaningful changes, road safety must be a priority.
Apr 1, 2019
Pedestrian and Bicyclist Scalable Risk Assessment Methods
Many transportation agencies are placing more emphasis on improving pedestrian and bicyclist safety and reducing the risk of a fatality or serious injury to pedestrians and bicyclists. Practitioners need a methodical approach to assess pedestrian and bicyclist risk for the purposes of identifying high-priority areas and transportation facilities for safety improvement, evaluating specific countermeasures and locations before and after improvements are made, and tracking safety performance measures over time to gauge progress toward established goals.
Apr 1, 2019
President's Message - Safety: A Community Effort
President's Message - Safety: A Community Effort
Apr 1, 2019
Speed Limits: Leading to Change
In January 2019, the National Committee on Uniform Traffic Control Devices (NCUTCD) voted to send a ballot item to the Federal Highway Administration (FHWA) to revise language in the Manual on Uniform Traffic Control Devices (MUTCD) regarding the setting of speed limits. In January 2018, the NCUTCD established a task force to further understand the recommendations made by the National Transportation Safety Board (NTSB), Reducing Speeding Related Crashes Involving Passenger Vehicles. The task force conducted a survey in the spring of 2018 of the profession to identify practices and attitudes related to setting of speed limits, and 740 professionals completed the survey.
Apr 1, 2019