# Statistical Frequency Of Red Light Running: A Comparative Study

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#### Updated on Nov 19, 2012

Does it seem to you as though people are always running red lights? Mark Kramer thought so too, and decided to prove it in his mathematics project.

See figure for a look at Mark’s display.

Figure: Project display for “Frequency of red light running.”

### Hypothesis

I believe that I can mathematically demonstrate a high incidence of drivers running through red and yellow lights.

### Procedures

This project observed and recorded the occurrences of vehicles running red and yellow lights according to these definitions:

• Red lights:
• Police definition. A car that crosses the intersection or crosswalk line after the light has turned red.
• Observational definition. A vehicle that had time to stop, entered the intersection on yellow, and was less than halfway through the intersection when the light turned red.
• Yellow lights:
• Observational definition. A vehicle that had time to stop, entered the intersection on yellow, and was more than halfway through the intersection when the light turned red.

• All types of vehicles, including cars, trucks, sport utility vehicles, vans, recreational vehicles, motorcycles, and in rare cases, buses and a police car, were observed.
• The observations were performed at the intersection of College Boulevard and Oceanside Boulevard in 2000 and at El Camino Real and College Boulevard in 2001.
• A total of 28 observations, done from a parked car, were performed in half-hour shifts, for a total of 14 hours.
• At each intersection, observed seven left-turn lanes and seven straight lanes, two lanes at a time (either two straight or two left lanes going in the same direction).
• All runners of red and yellow lights were marked down on a pre-made tally chart, noting the type of vehicle, day of the week, time, weather conditions, total number of vehicles passing through intersection, number of light changes, and observed traffic pattern.

### Results

Using statistical extrapolation (which just means estimating unknown information by projecting known information) and the combined statistics from 2000 and 2001, it was discovered that a red light is run every 5.6 minutes at these two intersections.

### Conclusions

My hypothesis that a high incidence of drivers run through red and yellow lights is correct, according to the tests done.

Although I ran the tests at only two of the busiest intersections in the city, I think caution when entering an intersection is always a wise choice considering how often people run red lights.