1. Signal Timing Design Example Problems

2. Intersection of Michigan Avenue and Hewitt Road

4. HEWITT ROAD

6. SOLUTIONS

7. Michigan and Hewitt Assume the following phasing plan.

8. Assume the through and left-turn lane at the NE Bound approach is used as an exclusive left-turn lane during the peak hour. Assume Saturation flow (S): S Thru = 1800 vphgpl, S Left = 1200 vphgpl Y NE(split phase) = Max [1102/(1200*2), 363/1800, 102/1800] = 0.46 0.20 0.06 Y NE = 0.46 Michigan and Hewitt Cycle Length Calculation

9. Y SW(split phase) = Max [13/1200), (313+21)/(1800*2)] = 0.01 0.09 Y SW = 0.09 Y NS(thru and permitted left turn phase) = Max [82/1200, (77+26)/1800, 35/1200, (490+31)/(1800*2)] = Max [0.07, 0.06, 0.03, 0.14] Y NS = 0.14 Left turn-lane critical volumes were considered in Y NS (although permitted), since there is not an exclusive left-turn phase for both directions

10. 1.5L + 5 1 -  y i L = sum of lost time per phase # Phases = 3 L = 2(3) = 6 sec  y i = 0.46 + 0.09 + 0.14 = 0.69 1.5*6 + 5 1 – 0.69 Assume C = 60 sec. Cycle Length Calculation C = C = = 14/0.31 = 45 sec

11. Assume 85 th Percentile Speed on Michigan and Hewitt is approximately 45 mph = 66 fps v Y = t + 2(a+gG) = 1 + 66/20 = 4.3 sec Assume width to clear Michigan Avenue = 100 ft Assume width to clear Hewitt Avenue = 100 ft AR = (W + L)/v AR = (100+20)/66 = 1.8 sec Clearance Interval per phase = 4.3 sec + 1.8 sec = 6.1 sec Total Clearance Time = (6.1 sec) ( 3 phases) = 18.3 sec Net Green time = cycle length – total clearance time = 60 – 18.3 = 41.7 sec Clearance Interval Design

12. Calculation of Splits NE Bound Michigan = 41.7(0.46/0.69) = 27.8 sec SW Bound Michigan = 41.7(0.09/0.69) = 5.4 sec NS Bound Hewitt = 41.7(0.14/0.69) = 8.5 sec Resulting Signal Timing Plans G = 27.8 G = 5.4 G = 8.5 Y = 4.3 Y = 4.3 Y = 4.3 AR = 1.8 AR = 1.8 AR = 1.8

13. Hewitt and Ellsworth Assume the following phasing plan.

14. Assume Saturation flow (S): S Thru = 1800 vphgpl, S Left = 1200 vphgpl Y EW (Left) = Max [98/1200, 7/1200] = 0.08 0.006 Y EW (Left) = 0.08 Y EW (thru with permitted lefts) = Max [220/1800, 206/1800, (289+56)/(1800*2)] = 0.12 0.11 0.09 Y EW THRU = 0.12 Left turn-lane critical volumes were NOT considered in Y EW (although permitted), since there is an exclusive left-turn phase for both directions Hewitt and Ellsworth

15. Assume 70% of left-turn volumes and 50% of thru and right turn volumes go during the NB Split phase. Y NB (split) = Max [(289*0.7)/1200, (695+38)*(0.5)/(1800*2)] = 0.17 0.10 Y NB (split) = 0.17 Y NS (thru and permitted lefts) = Max [(289*3)/1200, (695+38)*0.5/(1800*2), 103/1200, (324+120)/(1800*2)] = Max [0.07, 0.10, 0.08, 0.12] Y NS (thru and permitted lefts) = 0.12 Left turn-lane critical volumes were considered in Y NS (although permitted), since there is not an exclusive left-turn phase for both directions and the left-turn demand has not dissipated.

16. 1.5L + 5 1 -  y i L = sum of lost time per phase # Phases = 4 L = 2(4) = 8 sec  y i = 0.08 + 0.12 + 0.17 + 0.12 = 0.49 1.5*8 + 5 1 – 0.49 Assume C = 90 sec, since there are 4 phases and total clearance interval time may be  24 sec. Cycle Length Calculation C = C = = 33 sec

17. Assume 85 th Percentile Speed on Hewitt and Ellsworth = 45 mph = 66 fps v Y = t + 2(a+gG) = 1 + 66/20 = 4.3 sec Assume width to clear Hewitt Road = 80 ft Assume width to clear Ellsworth Road = 80 ft Clearance Interval Design

18. All Red, AR = W + L = (80+20)/66 = 1.5 sec V Clearance Interval per phase = 4.3 sec + 1.5 sec = 5.8 sec/phase Total Clearance Time = (5.8 sec) ( 4 phases) = 23.2 sec Net Green time = cycle length – total clearance time = 90 – 23.2 = 66.8 sec Clearance Interval Design

19. Calculation of Splits Green time for: EW Left = 66.8(0.08/0.49) = 10.9 sec EW Thru = 66.8(0.12/0.49) = 16.4 sec NB Split = 66.8(0.17/0.49) = 23.2 sec NS = 66.8(0.12/0.49) = 16.3 sec Resulting Signal Timing Plans G = 10.9 G = 16.4 G = 23.2 G = 16.3 Y = 4.3 Y = 4.3 Y = 4.3 Y =4.3 R* = 73.3 R* = 67.8 R* = 61.0 R* = 67.9 AR = 1.5 AR = 1.5 * Excludes All Red Time

20. Impact of Traffic Signal Systems on Traffic Crashes EXAMPLES

21. Intersection: Seven Mile & Ryan

22. BEFORE PERIOD COLLISION DIAGRAMS June 1995 – May 1996June 1994 – May 1995

23. BEFORE PERIOD COLLISION DIAGRAM June 1996 – May 1997

24. AFTER PERIOD COLLISION DIAGRAMS June 1997 – December 1997 January 1998 – December 1998

25. AFTER PERIOD COLLISION DIAGRAMS January 2000 – December 2000January 1999 – December 1999

26. AFTER PERIOD COLLISION DIAGRAM January 2001 – December 2001

27. Yearly Trend Analysis for Total and Injury Crashes for the Intersection of Seven Mile Road and Ryan Road Comparison of ‘Before and After’ Crashes for the Intersection of Seven Mile Road and Ryan Road

28. Intersection: Seven Mile & John R.

29. BEFORE PERIOD COLLISION DIAGRAMS September 1994 – August 1995 September 1995 – August 1996

30. BEFORE PERIOD COLLISION DIAGRAM September 1996 – August 1997

31. AFTER PERIOD COLLISION DIAGRAMS September 1997 – August 1998 September 1998 – August 1999

32. AFTER PERIOD COLLISION DIAGRAMS September 1999 – August 2000 September 2000 – August 2001

33. AFTER PERIOD COLLISION DIAGRAM September 2001 – December 2001

34. Yearly Trend Analysis for Total and Injury Crashes for the Intersection of Seven Mile Road and John R. Road Comparison of ‘Before and After’ Crashes for the Intersection of Seven Mile Road and John R. Road

35. Intersection: Hubbell & Puritan

36. BEFORE PERIOD COLLISION DIAGRAMS November 1993 – October 1994 November 1994 – October 1995

37. BEFORE PERIOD COLLISION DIAGRAM November 1995 – October 1996

38. AFTER PERIOD COLLISION DIAGRAMS November 1997 – October 1998 November 1998 – October 1999

39. AFTER PERIOD COLLISION DIAGRAMS November 1999 – October 2000 November 2000 – October 2001

40. AFTER PERIOD COLLISION DIAGRAM November 2001 – December 2001

41. Yearly Trend Analysis for Total and Injury Crashes for the Intersection of Hubbell Road and Puritan Road Comparison of ‘Before and After’ Crashes for the Intersection of Hubbell Road and Puritan Road