Is driving in a hot vehicle safe?

Area of Science:

• Environmental Science
• Human Factors Engineering
• Automotive Safety

Background:

• Passenger cars parked in direct sunlight can reach extreme internal temperatures.
• Elevated temperatures inside vehicles pose risks to driver cognitive and physical performance.
• Existing heat stress models need adaptation for automotive environments.

Purpose of the Study:

• To investigate thermal conditions in parked passenger cars.
• To assess the impact of these conditions on driver performance.
• To develop heat stress thresholds for automotive applications.

Main Methods:

• Conducted twelve tests across four different vehicles.
• Utilized a heat stress model to predict driver core temperature (tcore) after 60 minutes.
• Adapted algorithms to calculate fractional performance loss based on tcore for driving-related tasks.

Main Results:

• Predicted fractional performance losses up to 50% for simple driving tasks (e.g., maintaining a straight course).
• Extreme thermal conditions predicted performance losses exceeding 75% for complex tasks (e.g., signal identification and reaction time).
• Results highlight significant driver impairment due to heat exposure in parked vehicles.

Conclusions:

• Recommended implementing new technical standards for heat stress assessment in vehicles.
• Proposed a lower threshold (tcore ≈ 37.1°C) for demanding mental tasks.
• Suggested a higher threshold (tcore ≈ 37.2°C) for simpler driving tasks.