Civil Engineering

Transportation Research

Developing a National Education Strategy for the National Guide to Sustainable Municipal Infrastructure (the Guide)
S. Easa, L. Amleh

A first for Canada, the Guide provides a road map for municipal officials and others to the best available solutions to today's municipal infrastructure challenges. This six-month research contract is will develop a national education strategy that is expected to achieve the Guide's vision of becoming a dynamic source of leading/relevant municipal infrastructure practices. The strategy will also help educate practitioners and decision-makers on the Guide's use and content.

(Funding Agencies: Federation of Canadian Municipalities, 2003 - 2004)


Study of the Causes of Motor Vehicle Collisions
B. Persaud

The long-term goal of the research program is to institute a truly multidisciplinary approach to collision investigation. It is expected that the talents available in the many disciplines involved in injury prevention research civil engineering, vehicle engineering, human factors and epidemiology will be harnessed in achieving this goal. The expectation is that this approach will facilitate the development of effective countermeasures that involve combinations of engineering (vehicle and highway design), enforcement (regulation or traffic law enforcement) and education (driver training and testing). The Phase 1 report, completed in June 2003, documents the initial phase of the component of this research program which has become known as a Causes of Collisions study. The fundamental objectives of this phase were to conduct a literature review and a survey of jurisdictions to identify gaps in our current knowledge on causes of motor vehicle collisions and to propose a methodology for the study of the factors related to the causes and consequences of collisions.

(Funding Agency: Transport Canada, 2002 - 2003)

Safety Performance Assessment of Ontario Freeway Interchanges, Ramps, and Ramp Terminals
B. Persaud

The project developed new safety performance functions for interchanges, ramps and ramp terminals for Ontario freeways, using negative binomial regression that relates collision frequency to traffic volumes and basic entity characteristics. These safety performance functions were applied for network screening using two varieties of the potential for safety improvement (PSI) index method, one based on expected collision frequency and one based on expected collision frequency in excess of what is considered normal. This approach has been developed through Ontarios Science of Highway Safety research programme to overcome the limitations of conventional screening methods. The rankings of screened sites based on the two methods are compared. A third method, which is based on an index of a high proportion of a specific collision type, is applied to ramp terminals by way of illustration to identify those sites with high proportions of specific collision types. This method does not require safety performance functions or traffic volumes but does require the application of some fairly intricate statistical methodology. A comparison of the rankings so obtained with those derived by applying the PSI methods for a specific accident type suggests that the method of screening for high proportion of specific accidents can be a useful alternative to PSI index method where safety performance functions and/or traffic volumes are not available since, unlike the PSI Index method, it does not require these inputs in doing network screening for specific collision types.

(Funding Agency: Ministry of Transportation, Ontario)


Decision Making Tools for Engineering Road Safety
B. Persaud

The rationale is that most decisions in the planning, design and operation of roads have safety implications. For example, a designer of a new road needs to provide a balance between safety and cost in making decisions on design elements. Similarly, a decision on whether a measure, e.g., illumination, is "warranted" on an existing road requires a consideration of its expected safety impact. In the case of operations, it seems desirable for safety to be explicitly considered in route guidance algorithms for intelligent transportation systems and therefore to be reflected in motorists travel route decisions. The research aims to provide advanced tools that would be appropriate in considering the safety repercussions of decisions related to the planning, design and operation of roads. Specific aspects include: formal procedures to replace ad hoc safety warrants in deciding when improvements such as illumination are required; tools for deciding where safety improvements are required and for deciding on appropriate safety measures; tools for designing safety into new roads; and tools for traffic management improvements, including intelligent transportation systems. The research will also continue to improve the knowledge base for using these tools by developing more practical procedures for estimating the safety repercussions of decisions. And research will also aim to facilitate the application of the tools with the use of processes such as GIS.

(Funding Agencies: NSERC, 2002 - 2007)


Safety Implications for Design Innovations
B. Persaud

This project assesses the effects of vehicle design on safety, controlling for other characteristics of people and the environment involved in traffic crashes. This general objective is initially addressed in research on side-impact crashes. There are several interrelated studies: the intense multidisciplinary study of side impact crashes and resulting injuries, the analysis of data from population-based insurance claims, and experimental work of crash tests and simulations. All of these require the application of novel methodological approaches, the development of which is an important secondary objective. The main benefit is the development of accelerated, but still reliable, means of testing of the impact of vehicle design elements on safety through field observations and computer simulations. The project involves researchers from Ryerson, Ecole Polytechnic, University of Montreal, The University of British Columbia and the University of Toronto (the lead institution).

(Funding Agency: NCE Auto 21st, 2001 - 2004)


Comprehensive Highway Safety Improvement Model
B. Persaud

This is an on-going project with expected completion in 2005 for the U.S. Federal Highway Administration (FHWA) under sub-contract to Midwest Research Institute). Dr. Persaud is leading a Ryerson University team involved in various aspects of this project that is developing advanced software tools and processes for the identification of highway locations for safety treatment and for the evaluation of treatments for sites so identified. More information on this project is at www.safetyanalyst.org.

(Ryerson research sub-contract to Midwest Research Institute on a research project for the US Federal Highway Administration, (2001 - 2007)

Crash Reduction Factors for Traffic Engineering and ITS Improvements
B. Persaud

Crash reduction factors (also known as accident reduction factors or accident modification factors) provide a computationally simple and quick way of estimating crash reductions. Many states have a set of crash reduction factors that are used for estimating the safety impacts of various types of engineering improvements, encompassing the areas of signing, alignment, channelization, and other traffic engineering solutions. Typically, these factors are computed using before-and-after comparisons, although later research also has suggested the use of cross-sectional comparisons. Currently, crash reduction factors (CRFs) are used often in the short-term programming process (e.g., an annual review of hazardous locations statewide) to quickly yield a list of improvement sites where the "biggest bang for the buck" is likely. Reliable CRFs could also be used in project development for nonsafety as well as safety-specific projects and could assist agencies in deciding on policies affecting general project design (e.g., context-sensitive design solutions, and traffic calming). Four impediments exist to using CRFs: (1) While presumed to be based on some type of data analysis, the origins of the factors used in practice are not always clear. Factors that vary from state to state may reflect regional disparities or may indicate a need for updates. (2) CRFs have not been developed for many ITS improvements or other operational strategies. For example, on an urban freeway, the installation of an 8-ft shoulder and the initiation of a safety service patrol both have tangible safety benefits, but CRFs currently exist only for the former. (3) CRFs factors are designed for individual improvements, yet multiple improvements usually occur when an intersection or roadway segment is being rebuilt. (4) existing CRFs often reflect changes in accident experience resulting from improvements at sites experiencing unusually high accident rates. Because of this, the impacts of the improvements tend to be exaggerated (i.e., the phenomenon of regression to the mean). It should be recognized that CRFs are a tool for quickly estimating the impact of safety improvements. Their strength is that they are relatively quick to use; their weakness is that they are based on limited data. Thus, it is desirable to develop CRFs that consider additional elements (e.g., time of day, weather, and percent of trucks).

The objective of this project is to develop reliable CRFs for traffic engineering, operations, and ITS improvements. Reliable CRFs, at a minimum, meet the following criteria:

a) The CRFs are methodologically and statistically valid. Expert judgment is not a substitute for rigorous analysis. Separate values for CRFs (or a method for adjusting the CRFs) are tabulated that account for various influencing factors such as the highway facility, operating condition, weather, time of day, percentage of truck traffic, and pre-existing crash history as appropriate.

b) The applicability of the CRF is known and documented. For example, some CRFs may denote an impact on crashes only at a specific location whereas other CRFs may affect crashes for an entire stretch of roadway, or some CRFs may apply only to specific accident types or to specific pre-existing conditions (e.g., high percentages of wet weather crashes).

c) The CRFs reflect improvements or combinations of improvements that are of interest to DOTs. Such improvements could, for example, include (i) adding a centerline rumble strip, (ii) modifying a signal in conjunction with adding a left-turn lane or (iii) increasing the frequency of a safety service patrol in concert with improved variable message sign (VMS) signing.

d) The CRFs should represent the different crash categories that reflect the impact of the improvement. Crash categories might include total crashes, severe injury crashes, property damage only crashes, and specific crash types (such as rear end and angle).

e) The CRFs reflect variability. The best estimate of the CRFs, along with some technique that reflects their variability (such as ranges, confidence intervals, standard deviation, or some other technique) should be presented.

(Ryerson research sub-contract to the University of North Carolina Highway Safety Research Center on National Cooperative Highway Research Programme contract for Project 17-25). (2004-2007)

Mitigation of fatigue related crashes
B. Persaud

The project isolates the relative contributions of engineering factors fatigue related crashes occurring during periods of low circadian rhythms. The objective is to investigate how these accidents can be mitigated through highway engineering treatments. Other aspects of this multidisciplinary project investigate factors and countermeasures related to drivers and vehicles.

(Grant from the Canadian Institutes for Health Research (CIHR) 2006-07)



Past PROJECTS (since 2000)

Validation of Accident Models for Intersections

B. Persaud

No description.

(Ryerson research sub-contract to Georgia Tech. on U.S. Federal Highway Administration project, Nov 2000 - Sept 2002)


Development and Refinement of Safety Management Tools and Associated Knowledge Bases

B. Persaud

No description.

(Funding Agencies: NSERC, 1998 - 2002)