Chapter 18, Problem 25ICA

Today, most traffic lights have a delayed green, meaning there is a short time delay between one light turning red and the light on the cross-street turning green. An industrial engineer has noticed that more people seem to run red lights that use delayed green. She conducts a study to determine the effect of delayed green on driver behavior. The following data were collected at several test intersections with different green delay times. These data represent only those drivers who continue through the intersection when the light turns red before they reach the limit line, defined as the line behind which a driver is supposed to stop. The data show the “violation time,” defined as the average time between the light turning red and the vehicle crossing the limit line. as a function of how long the delayed green has been installed at that intersection.

Create a proper plot of the violation time (V, on the ordinate) and the time after installation (t, on the abscissa) for all three intersections on a single graph.

Use polyfit to determine linear models for each data set. For each model, add the trendline and the associated trendline equation to the graph. Use an appropriate location for the equations to clearly associate them with the correct trendline.