Incandescent Bulb and LED Brake Lights:Novel Analysis of Reaction Times

Ramaswamy Palaniappan, Surej Mouli, Evangelia Fringi, Howard Bowman, Ian McLoughlin

Research output: Contribution to journalArticlepeer-review


Rear-end collision accounts for around 8% of all vehicle crashes in the UK, with the failure to notice or react to a brake light signal being a major contributory cause. Meanwhile traditional incandescent brake light bulbs on vehicles are increasingly being replaced by a profusion of designs featuring LEDs. In this paper, we investigate the efficacy of brake light design using a novel approach to recording subject reaction times in a simulation setting using physical brake light assemblies. The reaction times of 22 subjects were measured for ten pairs of LED and incandescent bulb brake lights. Three events were investigated for each subject, namely the latency of brake light activation to accelerator release (BrakeAcc), the latency of accelerator release to brake pedal depression (AccPdl), and the cumulative time from light activation to brake pedal depression (BrakePdl). To our knowledge, this is the first study in which reaction times have been split into BrakeAcc and AccPdl. Results indicate that the two brake lights containing incandescent bulbs led to significantly slower reaction times compared to eight tested LED lights. BrakeAcc results also show that experienced subjects were quicker to respond to the activation of brake lights by releasing the accelerator pedal. Interestingly, analysis also revealed that the type of brake light influenced the AccPdl time, although experienced subjects did not always act quicker than inexperienced subjects. Overall, the study found that different designs of brake light can significantly influence driver response times.
Original languageEnglish
Article number9351984
Pages (from-to)29143-29152
Number of pages10
JournalIEEE Access
Early online date10 Feb 2021
Publication statusPublished - 2021

Bibliographical note

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  • Brake light reaction time
  • LED brake light
  • brake light stimulation
  • bulb vs LED response time
  • road safety


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