CE 552 Week 13

3. CE 552 Week 13 Identifying problems and solutions – The safety audit (materials, chapter 9) Responses/countermeasures/Crash reduction factors/AMFs (materials, chapter 10)

4. Improve safety • Interdisciplinary teams • Existing or new roadway • Planning • Construction • Design • ID problem elements • ID opportunities

5. Team quals: • Crash investigation • Traffic engineering • Road design • Enforcement • Maintenance • EMS • Human factors • Background info • Plans, volumes, crash data

16. Development of countermeasures

17. Principles of countermeasure development • The process of countermeasure development should aim to • Determine a Range of measures likely to influence the dominant crash types and road features • Select countermeasures based on professional judgment and experience that can expected to reduce the number or severity of dominant crashes From Ogden, Chapter 7

18. Principles of countermeasure development (continued) • Check to see if adopted countermeasures have any undesirable consequences in • Safety terms • e. g. lead to an increase in number or severity of another crash type • Traffic efficiency • Environmental terms • Be cost-effective • Maximize the benefits from HRL program • Be efficient • Produce benefits which outweigh costs

19. Principles of countermeasure development (continued) • A safe road is one that recognizes the realities and limitations of human decision making • The management of road safety must ensure the road environment not place demands upon the driver that are beyond the driver’s ability to manage, or which are outside normal road user expectations • What are the characteristics of a safe road?

20. Characteristics of a safe road • A safe road is defined as one which is designed and managed so that it: • Warns the driver of unusual features • Informs the driver of conditions to be encountered • Guide the driver through unusual sections • Control the driver’s passage through conflict points and road links • Forgives a driver’s inappropriate behavior

21. Intersections • The main design principles for intersections are • Minimize the number of conflict points and thus the opportunity for crashes • T-intersections and roundabouts have fewer conflict points than 4-way intersections • Give precedence to major movements through • Alignment • Delineation • Traffic control • Separate conflicts in space or time

22. Intersections (continued) • Control the angle of conflict • Crossing streams of traffic should intersect at a right angle or close to it • Merging streams should intersect at small angles to ensure low relative speed • Define and minimize conflict areas • Define vehicle paths • Ensure adequate sight distances • Control approach speed using • Alignment • Lane width • Traffic control • Speed limits

23. Intersections (continued) • Provide clear indications of right-of-way requirements • Minimize roadside hazards • Provide access to use intersection for • Vehicular traffic • Special provisions for heavy vehicle and public transportation vehicles • Non-vehicular traffic • Pedestrians and other vulnerable road users • Simplify the driving task • Minimize road user delay Roundabouts usually include to some degree all of the above principles

24. Mid-block locations • The principles for design and operation of non-intersection locations include • Consistent standards of horizontal and vertical alignments • Develop roadway cross sections to suit road function and traffic volumes • Delineate roadway and vehicle paths • Standards of access control from abutting land use • Ensure that roadside environment is clear or forgiving

25. Mid-block locations (continued) • Overlaying all of the above principles is a vital need to consider particular needs of all road user groups • Careful consideration of these needs will ensure the quality of final treatment • Pedestrians have special needs that should be separately considered when investigating safety problems and developing countermeasures • Special requirements of heavy vehicles • Negotiating low-radius turn • Traveling through horizontal curves with adverse super-elevation • Other user groups needs

26. Countermeasure selection • Matching solutions to problems • The key to selection of countermeasures is to concentrate on the particular crash types which identified in diagnosis phase • The final choice will be based upon judgment and experience • Utilizing countermeasures which have been successful in similar situations elsewhere

27. Criteria for countermeasure development • There are number of criteria for countermeasure selection • Technical feasibility • Can countermeasure provide an answer? • Does it have technical basis for success? • Economic efficiency • Is countermeasure likely to be cost effective? • Will it produce benefits to outweigh its costs? • Affordability • Can it be accommodated through program budget? • Should a cheaper solution be adopted?

28. Criteria for countermeasure development (continued) • Acceptability • Does the countermeasure target the problem? • Will it easily understandable by community? • Practicality • Is there likely to be a problem of non-compliance? • Can the measure work without unreasonable enforcement effort? • Political and institutional acceptability • Is the countermeasure likely to attract political support? • Will that be supported by the organization responsible for its installation and on-going management?

29. Criteria for countermeasure development (continued) • Legal compatibility • Is the countermeasure a legal device? • Will users breaking any law by using it in the way intended? • Compatibility • Is the countermeasures compatible with other strategies which have been applied in similar situations? • It can be seen that adapting countermeasures to particular problem is a complex process. • Development of countermeasures requires understandable technical and institutional framework to provide the guideline principles and motivation for action

30. From Garber …

32. From: Khisty

37. 1990 NHTSA/FHWA effective safety measures What’s new since then that you know about?