Week 1 lecture - Part 2.pdf

CVEN4405 Human Factors in Civil and Transport Engineering Week 1 lecture - Part 2 Introductory topics in HF Dr Milad Haghani Research Centre for Integrated Transport Innovation (rCITI) School of Civil and Environmental Engineering • • • • • • • Introductory topics in Human Factors Definition an...

CVEN4405 Human Factors in Civil and Transport Engineering Week 1 lecture - Part 2 Introductory topics in HF Dr Milad Haghani Research Centre for Integrated Transport Innovation (rCITI) School of Civil and Environmental Engineering • • • • • • • Introductory topics in Human Factors Definition and historical overview The role of human errors in road accidents Cognitive characteristics and limitations Conceptual theories Global road accident statistics Risk and exposure The cost of road trauma Risk and Exposure • The number of fatalities and injuries alone are seldom sufficient, and can even be misleading when assessing road safety problems • Road risk can be generally defined as the probability of crash/fatality occurrence • Ni is the predicted average crash frequency crashes in road segment (i); L is the segment length (in km); exposure is most often expressed through the annual average daily traffic [AADT vehicles/day]; and a, b, c are coefficients to be estimated. • In practice, there are different measures of the amount of exposure, all with different advantages and limitations, but can be broadly classified in two groups: • Traffic estimates: vehicle-kilometers of travel, road length, fuel consumption, and vehicle fleet. • Persons-at-risk estimates: person-kilometers of travel, number of trips, time spent in traffic, driver population, and population Exposure • Exposure is a critical factor in risk analysis and one of the primary predictors of crashes and other harmful events: • Per Capita: A very basic measure of exposure is the population of a given geographic area. Per capita means per population, which might be expressed per thousand or per million people. • Licensed Drivers: Another basic measure of exposure is the number of licensed drivers. This is similar to the population-based measure of exposure (per capita) but limits the population to those with a driver license • Registered Vehicles: The number of registered vehicles is a common measure of exposure for computing and comparing crash rates over time • Vehicle-Kilometer Travelled: VKT is applicable to crash risk related to motor vehicles. This measure of exposure accounts for the number of vehicles on the roadway and the distance traveled by those vehicles. Exposure • The previous measures of exposure help to compare crash risk among general groups (e.g., populations, regions, and facility types), but how would you measure the crash risk for a single site (e.g., intersection or roadway segment)? • AADT: For roadway segments such as tangents, curves, and ramps, the annual average daily traffic (AADT) and segment • Crash rate is the ratio of crash frequency to exposure as shown: • Crash rates implicitly assume a linear relationship between crash frequency and the measure of exposure; however, many studies have shown that the relationship between crashes and traffic volume is often nonlinear Hypothetical SPF relating crash frequency and traffic volume. Traffic Conflicts and Surrogate Safety Measures • A traffic conflict is defined as an event involving at least two road users, where one road user makes a nontypical maneuver (e.g., harsh maneuver, traffic rules violation) resulting in a crash avoidance maneuver from the other road user. Several studies have shown that the number and types of traffic conflicts correlate very well with actual crashes in many contexts. • The indicators used are referred to as “surrogate safety measures” and typically include (but are not limited to): TTC—time to collision; PET—postencroachment time, deceleration rates, and so on. • Post Encroachment Time (PET) is one such measure and represents the time difference between a vehicle leaving the area of encroachment and a conflicting vehicle entering the same area. https://www.youtube.com/watch?v=rSABRwcVvUU • The time-to-collision (TTC) concept was introduced in 1971 by the US researcher Hayward. A TTC value at an instant t is defined as the time that remains until a collision between two vehicles would have occurred if the collision course and speed difference are maintained. https://www.youtube.com/watch?v=R2sF_RYHhj8 • • • • • • • Introductory topics in Human Factors Definition and historical overview The role of human errors in road accidents Cognitive characteristics and limitations Conceptual theories Global road accident statistics Risk and exposure The cost of road trauma Cost of road trauma Cost of road trauma • Road trauma cost the Australian economy an estimated nearly $30 billion in 2015 • This figure is equivalent of 1.3% of GDP • Total social cost of road crashes in Australia for 2016 was $33.16 billion • This equates to 2% of GDP *Note that Australia’s 2017-2018 GDP growth rate was 2.9% (according to ABS) Cost of road trauma Cost of road trauma • Value of a statistical life (VSL) = Lost potential of an individual to society in economic and social terms. • An economic concept used to estimate the monetary value associated with reducing the risk of a premature death due to various factors, such as workplace accidents, environmental hazards, or public health policies. It represents the amount of money that society is willing to spend to prevent one statistical death on average. • VSL is a crucial tool in cost-benefit analysis for evaluating public policies and regulations aimed at improving safety and health. By assigning a monetary value to human life, policymakers can assess the potential benefits of regulations that reduce risks and improve safety against their associated costs. • It's important to note that VSL is a statistical and economic measure and does not represent the intrinsic or moral value of an individual's life. Instead, it provides a way to assess the trade-offs between allocating resources for safety measures and other societal needs when making policy decisions. • The actual value of statistical life can vary between different countries, contexts, and studies. • VSL is estimated to be about $4.1million • This figure has been utilised to determine that road fatalities in Australia in 2015 cost about $5 billion. Why do we need to estimate cost of road accidents • One of the purposes of estimating costs of road accidents is the evaluation of the benefits of road safety measures. • Another purpose is the ex-post representation of the extent of consequences in monetary terms to illustrate the burden of injuries, and compare this with such other costs, as for instance, costs for other types of injuries or diseases. • A third purpose of costing is to estimate the external costs of road accidents in order to internalise various economic costs to influence road user behavior. • A fourth purpose is to use estimates as a basis for judicial assessments of the sums paid in compensation for damages and other lost resources. Value of life and injuries • What is the value of reducing the likelihood of physical risk and reducing fatalities and fatal/nonfatal casualties? • The value of risk reduction per se is a measure of how much society is willing to pay (WTP) in addition to the summary of health care costs, gross lost production, cost of property damage, and administration for improved traffic safety. • Value of a statistical life (VSL) = Lost potential of an individual to society in economic and social terms. There are two main approaches to calculating the VSL: • The Human Capital Approach (HCA): This approach is grounded in the idea that an individual's life has economic value based on their future earnings and productivity potential. The VSL is calculated by comparing the present value of an individual's future earnings if they face a particular risk of premature death (e.g., in a hazardous job) to the present value of their future earnings if they do not face that risk. The difference in these two values represents the economic value of reducing the risk of premature death. • The Willingness to Pay (WTP): Stated Preference (SP)/Revealed Preference (RP) Value of life and injuries • The HC approach rests on accounting principles: The benefit of avoiding a premature death is given by the present value of the income flow the economy could lose in that case. • The human-capital approach does not reflect the value ascribed by the society to a human life. • More appropriately, the value of risk reductions (VRR)—initially known as the value of a statistical life (VSL)—is based on subjective preferences and given by the amount of money that individuals are willing to pay for reducing the risk of their premature death while performing a certain risky activity. • The VRR for road contexts was estimated originally using contingent valuation (CV), standard gamble, or the chain method, but the approach, in general, was heavily criticised by specialists in human behaviour and economics. • People were confronted with situations expressing risk as tiny probabilities, and needing a tradeoff between risk and money to arrive at a monetary value. Value of life and injuries • Some authors have proposed a different approach based on Stated Choice (SC) techniques. • In an SC survey, individuals are asked to choose among different alternatives, the attribute levels of which vary according to a statistical design aimed at maximising the precision of the estimates. • SC allows the analyst to mimic actual choices with a relatively high degree of realism, and for this reason most experts believe that it is an appropriate elicitation method for the valuation of non-market goods (such as life). • The alternative approach would be Revealed Choices (RC). The Stated Choice approach in VSL estimation Hensher, D.A., Rose, J.M., de Dios Ortúzar, J. and Rizzi, L.I., 2009. Estimating the willingness to pay and value of risk reduction for car occupants in the road environment. Transportation research part A: policy and practice, 43(7), pp.692-707. The Stated Choice approach in VSL estimation Subjective value of fatal crash injury (SVCR) or WTP for reducing risk The Stated Choice approach in VSL estimation The VRR studies find that the VRR associated with a fatality in western economies are in the range of $US8–$15 m. The evidence on VRR for various human injury classes (e.g., minor, serious, incapacitated) vary a great deal and appear to be typically in a range of $US200,000–$US1.5 m. The Stated Choice approach in VSL estimation Average, highest and lowest estimate of the VOSL (×1,000,000), in 1997 US dollars, for 30 road safety studies, ordered by magnitude. The Stated Choice approach in VSL estimation The Stated Choice approach in VSL estimation • • • • • • • Introductory topics in Human Factors Definition and historical overview The role of human errors in road accidents Cognitive characteristics and limitations Conceptual theories Global road accident statistics Risk and exposure The cost of road trauma References • Bahamonde-Birke, F. J., Kunert, U., & Link, H. (2015). The value of a statistical life in a road safety context—A review of the current literature. Transport Reviews, 35(4), 488-511. • De Blaeij, A., Florax, R. J., Rietveld, P., & Verhoef, E. (2003). The value of statistical life in road safety: a meta-analysis. Accident Analysis & Prevention, 35(6), 973-986. • Gross, F. (2021). Exposure: A Critical Factor in Risk Analysis. In R. Vickerman (Ed.), International Encyclopedia of Transportation (pp. 282-289). Oxford: Elsevier. • Hensher, D. A. (2021). Value of Life and Injuries. In R. Vickerman (Ed.), International Encyclopedia of Transportation (pp. 737-741). Oxford: Elsevier. • Hensher, D. A., Rose, J. M., de Dios Ortúzar, J., & Rizzi, L. I. (2009). Estimating the willingness to pay and value of risk reduction for car occupants in the road environment. Transportation research part A: policy and practice, 43(7), 692-707. • Oppenheim, I., & Shinar, D. (2011). Chapter 15 - Human Factors and Ergonomics. In B. E. Porter (Ed.), Handbook of Traffic Psychology (pp. 193-211). San Diego: Academic Press. • Persson, U. (2021). Costs of Accidents. In R. Vickerman (Ed.), International Encyclopedia of Transportation (pp. 196-199). Oxford: Elsevier. • Prato, C. G. (2021). Introduction to Transport Psychology. In R. Vickerman (Ed.), International Encyclopedia of Transportation (pp. 1). Oxford: Elsevier. • Smiley, A., & Rudin-Brown, C. (2021). Human Factors in Transportation. In R. Vickerman (Ed.), International Encyclopedia of Transportation (pp. 331-345). Oxford: Elsevier. • Yannis, G., & Papadimitriou, E. (2021). Road Safety. In R. Vickerman (Ed.), International Encyclopedia of Transportation (pp. 51-58). Oxford: Elsevier.