AbstractRoad Traffic Injury (RTI) is recognized as a public health problem. RTI claim more than

1.3 million lives each year across the globe. In India, road crashes led to the death of

150,785 persons during the year 2016. Therefore, it is vital to analyse crashes,

determine risk factors, and devise methods to mitigate the likelihood of a crash event

and estimate the effectiveness of each improvement on highways. This study aims to

develop the crash modification factors of the selected geometric interventions on

National Highways in India using the case-control method. First, objective is to identify

the most common crash pattern on the geometric elements of the National Highways

segments. Second objective is to evaluate the safety effectiveness of selected geometric

changes (shoulder width and median design) on highways using the case-control

method.

IntroductionAs per the government official data, 150,785 persons were killed and 494,624 injured in

road traffic crashes in India in 2016, despite low vehicle ownership. RTI are the 8th

leading cause of death in India in the year 2016. RTI are imposing huge economic loss

to the country. National highways constitute only 1.8% of the total length of roads

network in India but account for 35% of the fatalities. The fatality rate per km of the road

is the highest on NH with 0.67 deaths per km annually.

Fig. 1 Proportion of Road Category Fig. 2 Fatality per 10 Km length of NH in India.

and Road Fatalities for each category

of Highway.

The crash pattern of highways has revealed that truck and buses are involved in about

70% of the fatal crashes in both rural and urban highways. Vulnerable road users consist

of the majority of those who get killed on highways, which is significantly different from

the pattern of developed countries.

Fig. 3 Comparison of Rural and Urban Fig. 4 Share of road users fatalities in FatalitiesAccidents and India in 2016. in India, 2016.

The effects of highway element on safety due to change in the design, improvement or

proposed new countermeasure is studied with the help of various modelling approaches.

Indeed, a vital outcome of the highway safety studies is to understand how crash

frequency or crash severity gets affects due to change in geometric designs of highway

elements. This study aims to develop the crash modification factors of the selected

geometric interventions on National Highways in India using the case-control method.

First, objective is to identify the most common crash pattern on the geometric elements

of the National Highways segments. Second objective is to evaluate the safety

effectiveness of selected geometric changes (shoulder width and median design) on

highways using the case-control method.

ReferencesGross, F., and Jovanis, P. P. (2007). “Estimation of the Safety Effectiveness of Lane and

Shoulder Width: Case-Control Approach.” Journal of Transportation Engineering, 133(6),

362–369.

Gross, F., Jovanis, P. P., and Eccles, K. (2009). “Safety Effectiveness of Lane and

Shoulder Width Combinations on Rural, Two-Lane, Undivided Roads.” Transportation

Research Record: Journal of the Transportation Research Board, 2103(1), 42–49.

Gross, F., Persaud, B., and Lyon, C. (2010). A guide to developing quality crash

modification factors.

Mohan, D., Tiwari, G., and Bhalla, K. (2017). Road Safety in India: Status Report 2016.

Vogt, A., Bared, J. G., Pragmatics, I., Turner-Fairbank Highway Research, C., and

Anonymous. (1998). “Accident models for two-lane rural roads.” (98).

Woodward, M. (2014). Epidemiology Study Design and Data Analysis Third Edition.

Conclusions Epidemiological methods in road safety domain have shown hope to the researchers

of developing countries where data quality and others constraints hamper the

research as well as its outcome.

Case-control designs are well suited to investigate the effects of specific risk factors

while controlling for other variables that may influence the outcome in question.

The Case-control method is one of the promising solution to address confounders

variable problem.

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Industrial Significance Outcome of this study will be helpful to the agencies responsible for designing and

construction for highways.

Database framework will be developed, which will be useful for the agencies

responsible for crash data collection and management.

Proposed alternative approach will be useful for engineers and decision-makers to

determine the relative effectiveness of geometric improvements.

An Alternative Approach to Estimate Crash Modification Factor for Indian Highways

Laxman Singh Bisht, Geetam Tiwari*

MethodologyA matched case-control method will be used. Matched case-control method takes wellcare of confounding variables. Matching will be accomplished during the purposefulselection of controls. It provides an automatic adjustment of the relationship between therisk factor and outcome. Controls are matched to each case at a one-to-one ratio andmatching is completed on several factors to account for potential confounding. Figure 5illustrates the methodology of the matched case-control study design.

Fig. 6 Cases and Controls Setup study

Figure 5 Case Control Study Design Steps

The following steps will be taken for the matched case-control design:Step 1: Defining the Population, Cases and Controls. Step 2: Selection of sample from the identified population based upon outcome status i.e. whether the subject is the case or a control. Step 3: Assessment of the presence of risk factor.Step 4: Matching the controls to cases.Step 5: Conditional Binary Logistic Regression Modelling. Modelling approach shown in Figure 7.

Figure 7 Modelling Procedure for the study

Expected Results• Establishing the case-control method as an alternative approach of safety evaluation.• Estimation of CMF to check the benefits of improving the design of geometric

elements.• Expected estimate to show increase shoulder width and median design is associated

with decreasing number of crashes.• Calculated estimate to show that increase in shoulder width and median design

reduces severe crashes as the class of road increases.

Industry Day Theme # 4: {Sustainable Habitat}

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5Share of Road User Fatalitites

Pedestrians Bicycle MTWCar Bus Truck