This report reviews the crash cost reduction factors for countermeasures currently listed in the Alaska Department of Transportation and Public Facility's Highway Safety Improvement Program (HSIP) Handbook (HSIPHB) and provides revised values based on a literature survey of research and references. In addition, crash cost reduction factors are proposed for the five treatments that are not currently listed in the HSIPHB, including cable barrier median barriers, pavement traction enhancement, flashing yellow arrow left turn indications, HAWK pedestrian signals, and concrete median barriers. There is also a section on practices by other state DOT organizations. Alaska HSIP data is evaluated for safety effectiveness and the report provides an analysis and recommendations for the HSIP post evaluation process. This project and report also included research of the effectiveness of Active Advance Warning Flashers (AAWF) and shoulder rumble strips based upon Alaskan crash experience.

In an increasingly globalised world, despite reductions in costs and time, transportation has become even more important as a facilitator of economic and human interaction; this is reflected in technical advances in transportation systems, increasing interest in how transportation interacts with society and the need to provide novel approaches to understanding its impacts. This has become particularly acute with the impact that Covid-19 has had on transportation across the world, at local, national and international levels. Encyclopedia of Transportation, Seven Volume Set - containing almost 600 articles - brings a cross-cutting and integrated approach to all aspects of transportation from a variety of interdisciplinary fields including engineering, operations research, economics, geography and sociology in order to understand the changes taking place. Emphasising the interaction between these different aspects of research, it offers new solutions to modern-day problems related to transportation. Each of its nine sections is based around familiar themes, but brings together the views of experts from different disciplinary perspectives. Each section is edited by a subject expert who has commissioned articles from a range of authors representing different disciplines, different parts of the world and different social perspectives. The nine sections are structured around the following themes: Transport Modes; Freight Transport and Logistics; Transport Safety and Security; Transport Economics; Traffic Management; Transport Modelling and Data Management; Transport Policy and Planning; Transport Psychology; Sustainability and Health Issues in Transportation. Some articles provide a technical introduction to a topic whilst others provide a bridge between topics or a more future-oriented view of new research areas or challenges. The end result is a reference work that offers researchers and practitioners new approaches, new ways of thinking and novel solutions to problems. All-encompassing and expertly authored, this outstanding reference work will be essential reading for all students and researchers interested in transportation and its global impact in what is a very uncertain world. Provides a forward looking and integrated approach to transportation Updated with future technological impacts, such as self-driving vehicles, cyber-physical systems and big data analytics Includes comprehensive coverage Presents a worldwide approach, including sets of comparative studies and applications

The primary objective of this research was to systematically review past studies on rear end crashes, examine strategies for reducing rear end crashes on both freeway and non freeway facilities, and develop a set of rear end crash reduction strategies for use in Ohio, which will be appropriate for various traffic engineering solutions, operations and ITS improvements. Accordingly, this study conducted an extensive review of past literature related to rear end crashes and strategies to reduce them. A determination of specific strategies for a road safety improvement program requires an understanding of probable crash reduction capabilities for various geometric, operational and environmental factors on the roadways. Studies of crash reduction strategies have usually focused on before-and-after comparisons of specific locations or conditions. Based on the data provided by the Ohio Department of Transportation, this study attempted to examine the crash reduction capabilities for signalized intersections, unsignalized intersections, freeways and non-freeways where countermeasures were implemented. An attempt was made to compute crash reduction factors for rear end collisions for these roadway facilities. However, this task could not be performed because of the severe limitations in the ODOT countermeasure and roadway site data. In response to the researchers' request for additional data, ODOT decided not to proceed ahead with this research as it required the dedication of district resources that were not currently available. It was believed that breaking the project into smaller, more manageable pieces, would not yield results that would be statistically significant. There were also several national projects underway which would limit this project's benefits. In view of these circumstances, ODOT decided to terminate the contract for this project and all work stopped.

Crash reduction factors are used to identify and prioritize the most effective safety improvement measures, and prioritize and allocate available resources optimally for a highway safety improvement project. Simple before-and after analysis does account for the regression-to-the-mean bias. This research employs an Empirical Bayes (EB) methodology that overcomes the regression-to-the-mean property that is encountered in traditional before-and after analysis. Traffic, geometric and crash data for both the treatment and comparison sites were collected from Ohio in developing the crash reduction factors. Using data collected from Ohio, the EB methodology was applied in developing crash reduction factors for the following improvement categories: add a two-way left turn lane, install a median barrier, flatten slope and remove guardrail, remove or relocate a fixed object, flatten vertical curve, providing highway lighting and close median opening.