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Studying the effects of traffic noise and lane system on driver behavior in heterogeneous traffic using VR and physiological measurementsAuthor: Mayank Agrawal Date: 2020-06-26 Report no: IIIT/TH/2020/62 Advisor:Kavita Vemuri AbstractWith rapid urbanization, traffic congestion has become a severe problem in Indian cities with people spending a majority of their time stuck in traffic. While there are many reasons contributing to it - like bad road infrastructure, poor traffic management and heterogeneous traffic, a significant cause is identified as irrational driver behavior. These behaviors are mainly caused by various environmental factors like noise (both ambient and persistent honking), pedestrians, heterogeneous traffic, other vehicles not following rules, bad roads etc. The objective of the current study is to examine in particular two independent but conceptually linked external or environmental factors of honking and lane system on driver behavior. Of particular interest is the correlations between physiological changes, psychological states like anxiety/stress/frustration and decisions. A hypothesis based on observation and understanding of Indian roads, is that honking at high decibels though normalised and adapted by Indian road users is reflected on behavioral responses in addition to long term health effects. While there have been many studies addressing traffic congestion due to external factors, few cover driver behaviours caused due to these factors. In this study, we delve deeper into changes in driver behaviour due to one external attribute - that of persistent honking by a trailing vehicle. There have been studies on the effects of honking and most of them report better traffic flow because of honking. That is, honking is considered as an inter-vehicle or vehicle to pedestrian communication. The studies do not take into account changes in the driver behaviour due to honking - both honks of acoustic properties approved by certifying agencies and especially from non-standard honks as heard in traffic conditions in India where the current experiment was conducted. Honking, designed to be a tool for the drivers to communicate effectively and also to alert other road users, is often used on Indian roads as a mechanism to express frustration either due to traffic jams, a purely reflex action, a sense of entitlement (as a function of the cost/power of the vehicle) to the road and right of way etc., rather than to ensure safe driving. To analyse this effect, we looked at driver behaviour and his/her physiological measurements in the honking environment. These factors are inter-linked, as lane system in heterogeneous traffic leads to honking as traffic flow enabler or as aggression towards a smaller slow moving vehicle. As the first step, the validity of virtual simulators (with head mounted display and tactile controls) to present immersive experience and near real-life traffic conditions was tested. Hence, to study two environmental or external effects on driver behavior, the concept of lane adherence and honking was considered. We have chosen to simulate the real world rather than conduct a real-world experiment for two main reasons- 1. In real world traffic, we cannot ensure experimental control of honkingthat is, present the same or similar situations during the data collection time. Second, variation in the honking environment for each person creates inconsistencies in experiences and the data. To focus on the decision making aspect in driver behaviour, we need to ensure a similar environment to all participants. 2. It is difficult to impose traffic control in the real world. Creation of a controlled traffic environment multiple times, where different vehicles are moving synchronously, is difficult logistically and expensive. Thus, we solve this problem by using a Virtual environment, which can be controlled, manipulated and replicated as many times as needed. It provides a 360 degree 3D environment enabling different events like decision making and physiological data to be recorded synchronously. In the experiment for the lane system (experiment done with 30 participants), three scenarios were presented with the constant condition of the participant vehicle in the middle lane trailing a slow moving three-wheeler (autorickshaw). The time to reach the finish point, the decision to change lanes and errors in judgment were recorded. The results indicate that in heterogeneous traffic, roads with no lane marking allowed the driver to shift and overtake the slow vehicle while strict lane by barricades lead to high levels of irritation as per the self-report. The feedback on the simulator developed for this study was used as a basis for the Indian road scenario used in the second study. In the second study (experiment done with 45 participants) on the physiological and behavioral changes due to honking on the driver, pulse rate/ skin conductance and driving behavioral choices in the presented scenarios was recorded. We collected skin conductance/GSR values, as previous studies have shown that subjective high decibel noise affects the sympathetic nervous system (part of autonomic nervous system) which results in anxiety (indicated by perspiration). This perspiration is measured by the GSR/skin conductance sensors. For this study, a simulator in 3D VR was designed and developed with bots representative of different vehicles as present on Indian roads with their specific honks and speed. The participants recruited for the study have to drive a car in the simulated environment while wearing a VR headset, controlling the virtual vehicle with a steering wheel fitted with brake/accelerator controls and biosensors. The physiological readings are then correlated with their self reported data, behavioral data and the observational data. The results suggest that honking has a significant correlation to self-reported anxiety scores and recorded decision making. The findings from the two studies, emphasize the need for standardization of honk acoustics and awareness on its effects on other road users. The empirical data is of significance as existing studies generated theoretical models using particle based movement of the vehicles and honking as a tool to unplug traffic coagulation. Also, most of these models do not consider the driver behaviour change due to the noise pollution as a factor. Though further lane system designs need to be tested, from our studies, our hypothesis has been validated based on the significant effect certain acoustic properties (loudness and frequency) of the honk has on the driver behaviour. Thus, traffic models (especially for the Indian scenario) can be improved by including findings from empirical studies such as those presented in this thesis to arrive at realistic solutions. Full thesis: pdf Centre for Others |
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