To complete Part 1 follow the below instructions:
You will consider four intersections of width: 90, 120, 150, and 180 respectively.
For each intersection, you will assume four different posted speeds of 30, 35, 45, and 50 mph.
Based on the equations in your Excel template, you will calculate the Yellow Change Interval and the Red Clearance Interval.
You will calculate the total time to switch to Red by adding the Yellow Change Interval and Red Clearance Interval.
Traffic camera will snap a shot after the total calculated time and an allowance of 0.5sec to capture Red light violations.
Create four charts showing the change in the Yellow change interval, Red clearance interval, and the total Change time for each posted speed.
The equations used for
Y (sec) is ‘=(F4+((1.47*C4)/(2*G4+64.4*D4)))’
R (sec) is ‘=((E4+H4)/(1.47*C4))-1’
TV (sec) is ‘=I4+J4+0.5’
The Insurance Institute for Highway Safety, IIHSLinks 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, 2004Links to an external site.; Retting & Greene, 1997Links to an external site.; Van Der Horst, 1988Links to an external site.; McGee et al., 2012Links 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.Download Virginia Beach Signal Timing Information.
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.
