Estimating cost of road traffic injuries in Iran using willingness to pay (WTP) method

Abstract

We aimed to use the willingness to pay (WTP) method to calculate the cost of traffic injuries in Iran in 2013. We conducted a cross-sectional questionnaire-based study of 846 randomly selected road users. WTP data was collected for four scenarios for vehicle occupants, pedestrians, vehicle drivers, and motorcyclists. Final analysis was carried out using Weibull and maximum likelihood method. Mean WTP was 2,612,050 Iranian rials (IRR). Statistical value of life was estimated according to 20,408 fatalities 402,314,106,073,648 IRR (US$13,410,470,202 based on purchasing power parity at (February 27th, 2014). Injury cost was US$25,637,870,872 (based on 318,802 injured people in 2013, multiple daily traffic volume of 311, and multiple daily payment of 31,030 IRR for 250 working days). The total estimated cost of injury and death cases was 39,048,341,074$. Gross national income of Iran was, US$604,300,000,000 in 2013 and the costs of traffic injuries constituted 6·46% of gross national income. WTP was significantly associated with age, gender, monthly income, daily payment, more payment for time reduction, trip mileage, drivers and occupants from road users. The costs of traffic injuries in Iran in 2013 accounted for 6.64% of gross national income, much higher than the global average. Policymaking and resource allocation to reduce traffic-related death and injury rates have the potential to deliver a huge economic benefit.

Figure 1. Histogram of willingness to pay (IRR) for drivers (a), Histogram of logarithm of willingness to pay (IRR) for drivers (b).

Figure 2. Willingness to pay (IRR) among all road users.

Figure 3. Effects of several variables on WTP (IRR).

(a) shows that mean WTP increased up to 35 years old; it gradually reduced from ages 35 to 55 and increased again after the age of 55. (b) shows that people with higher commuting cost had higher willingness to pay. (c) shows that those who paid more to time reduction had higher willingness to pay. (d) shows that people who gave more to charity had higher willingness to pay.

Figure 4. A predictive plot of logarithm of willingness to pay(IRR) against pay to time reduction for different road users (A man with high school or diploma education, family size less than 4, middle income, have an accident experience, trip mileage  = 30 km, more pay to time reduction = 2,000IRR, middle health.