The Insurance Institute for Highway Safety
The Insurance Institute for Highway Safety, IIHS (Links to an external site.), states on their site that “Providing adequate yellow signal time is important and can reduce crashes. Studies have shown that increasing yellow timing to values associated with guidelines published by the Institute of Transportation Engineers can significantly decrease the frequency of red light violations and reduce the risk of total crashes, injury crashes, and right-angle crashes (Bonneson & Zimmerman, 2004 (Links to an external site.); Retting & Greene, 1997 (Links to an external site.); Van Der Horst, 1988 (Links to an external site.); McGee et al., 2012 (Links to an external site.))._
You will design an Excel spreadsheet that calculates the allowable yellow light interval before changing to red and the red clearance interval based on the Virginia Beach Signal Timing Information. (Links to an external site.)
The equations that you will implement in your Excel spreadsheet calculator are available on slide 5 of the Signal Timing information.
Your Excel Spreadsheet should show the following:
- Posted Speed Limit
- Adjusted Speed limit
- Intersection width
- Vehicle Length
- Yellow Change Interval
- Red Clearance Interval
- Total interval to come to a stop
You will create charts showing the change in the Yellow change interval, Red clearance Interval, and the total Change time for each posted speed used. You will discuss in Part 3 of your project your conclusion based on those results.
You can investigate in your Excel spreadsheet different reaction times, deceleration rates, and vehicle length.
Note: If you want to design an excel spreadsheet that calculates the most commonly used formulas in your field, then secure your instructor’s approval first. your instructor will provide you with specific formulas to implement.