Filling truck cabs with simulated daylight could benefit drivers’ health and improve road safety, a study has shown.
Engineers at Daimler, the parent company of Mercedes-Benz Trucks, have published the results of a two week research project into whether artificial daylight could improve the working environment for truckers.
To carry out the tests, Daimler researchers created a “Daylight+” module that could be installed in the cab of a truck to mimic daylight. The biggest challenge was to create light as close as possible to the level of daylight that has an effect on human biology, but was not so bright that a driver couldn’t actually see out the windows. An effective wavelength of between 460 and 490 nanometres was identified as the best option.
A team led by Daimler research director Siegfried Rothe installed the Daylight+ modules in truck cabs and recruited eight drivers to spend two weeks testing the system in Rovaniemi, Finland, during the darkest period of the year, where the district sees only three or four hours of daylight per day.
During the night, the test subjects slept in a normally darkened truck, but while driving were subject to tests with different levels of artificial daylight.
The team documented test results with support from co-researcher Dr Michael Schrauf and the use of electroencephalography (EEG), electrocardiography (ECG) and electrooculography (EOG) as well as other physiological measurements such as saliva samples (to ascertain levels of the sleep hormone melatonin).
Mental state and professional performance, which are closely related, were examined using standardised psychological test procedures and by recording vehicle data through the truck’s telematics system.
At the end of the two-week cycle, the individual drivers were interviewed. All said that they perceived the space inside the cab to be considerably more pleasant with the additional light filtered in.
“When designing the series of tests, we hadn’t even considered that the space might appear larger,” said Rothe, who estimates that it will take several months to sift and analyse the data from the experiments. “Only then we will be able to make a recommendation as to whether the test findings should lead to changes in the design of cab lighting.”