Some preliminary results are available from our documentation of driver’s reactions to the change of a traffic signal from red to green. This data is for the year 2018 and includes 174 observations.
The analysis involves examining the videotape of scenarios such as the one shown above. From the instant that the traffic signal turns green we document the delay before the brake lights of the stopped vehicles become extinguished. This is what is defined as the response delay. The average response delay for all 174 observations was 0.67 seconds. But the range of responses included a situation where the brake light was extinguished 4 seconds before the activation of the green signal. And there were 10 incidents where the brake lights were extinguished before the activation of the green signal. There were also numerous observations of delays well above 1 second. The greatest delay was over 3 seconds after the signal turned green. Thus even within this small dataset we can see some wide variance in the results.
We will have more to say about the relevance of this data after we have documented enough observations. In 2019 a much larger number of observations were made and these still need to be added to our spreadsheets.
In response to various client assignments a variety of other response data has been collected in the past. In some instances involving intersection collisions a test vehicle was purposely driven forward from a side road and then stopped prior to entering the intersection. Video cameras documented the delay before approaching drivers on the main road applied their brakes.
In other instances we have documented the approach of vehicles to a traffic signal just as the signal changed from green to amber. The decision to pass through the intersection without stopping or braking to a stop was documented via videotape.
These are examples of the testing that may be discussed in the future in combination with the data that is being discussed here. There are always persons who express their opinions on what drivers should or should not do in collision scenarios. Unfortunately much of this opinion is expressed without an understanding of human behaviour, specifically in the roadway environment. Hopefully, a discussion of observations that we made in the field will anchor some beliefs to objective fact.