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Development of countermeasures

Hossein NaraghiCE 590 Special Topics

SafetyMarch 2003

Time Spent: 6 hrs

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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

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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

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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?

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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

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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

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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

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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 delayRoundabouts usually include to some degree allof the above principles

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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

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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

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Countermeasure selection

Matching solutions to problems The key to selection of countermeasures

s 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

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Countermeasure selection (continued)

Tables 7.1 through 7.7 page 140-150, summarize treatments which found to be effective in relation to particular crash types Intersections with high speed traffic, 7.1 Intersections with low speed traffic, 7.2 Mid-block with high speed traffic, 7.3 Mid-block with low speed traffic, 7.4 Roads with high design speed, 7.5 Pedestrian facilities, 7.6 Railway crossing, 7.7

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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?

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Criteria for countermeasure development (continued)

Acceptability • Does the countermeasure target the problem?• Will it easily understandable by community?

Practical• 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?

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Criteria for countermeasure development (continued)

Legal• 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 adopt countermeasures to particular problems is a complex process.

Development of countermeasure requires understandable technical and institutional framework to provide the guideline principles and motivation for action

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Effectiveness and cost-effectiveness

Road safety countermeasures must be cost-effective as well as effective

Economic appraisal of road safety treatments is useful to present the findings of a study which used a Delphi method to seek expert opinion on which countermeasures were likely to be cost effective

Travers Morgan 1991, conducted a major survey of international experts in road safety Asking them to grade, on the basis of their

experience,a wide range of road features based on their effectiveness (ability to reduce crashes) and

cost-effectiveness (benefit to cost ratio)

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Effectiveness and cost-effectiveness (continued)

Twenty-one experts from US, Canada, UK, Sweden, Japan, New Zealand and Australia responded. The results are shown in table 7.8 (urban roads) and 7.9 (rural roads) pages 151 and 152

Results show that certain treatments, while perhaps being highly effective, are not cost-effective because of their high initial and on-going operational costs

There are a number of projects which are both effective and highly cost-effective, which are clearly desirable countermeasures