Traffic Signal Warrants Example Problem Tapan K. Datta, Ph.D., P.E.

Intersection of Main Street and 14th Street Major Street: Main Street 3-lane EB approach and 3-lane WB approach Speed limit = 50 mph Minor Street: 14th Street One left-turn lane and one shared through and right-turn lane 14th Street Main Street

12-hour Traffic Volumes MAIN STREET (TOTAL OF EB MINOR STREET TIME AND WB DIRECTION OF APPROACH VPH TRAFFIC) VPH 7:00 - 8:00 AM 500+780 = 1,280 145 8:00 - 9:00 AM 700+620 = 1,320 210 9:00 - 10:00 AM 300+43 5 = 735 120 10:00 - 11:00 AM 385+405 = 790 100 11:00 - 12:00 PM 450+420 = 870 110 12:00 - 1:00 PM 470+430 = 900 115 1:00 - 2:00 PM 280+320 = 600 85 2:00 - 3:00 PM 245+255 = 500 52 3:00 - 4:00 PM 225+325 = 550 50 4:00 - 5:00 PM 680+780 = 1,460 220 5:00 - 6:00 PM 70 0+750 = 1,450 205 6:00 - 7:00 PM 480+450 = 930 155

Warrants for Signalized Intersections Warrant 1: Minimum Vehicular Volume

satisfied when the volumes given in the table exits on major street and on the higher volume minor street for any 8 hours of an average day when 85th percentile speed of major street exceeds 40 mph 70 % of the requirements may be used

Warrant #1 Requirements (for 8 hours): Can use the 70% reduction, since 85th percentile speed > 40 mph Major Street (total of both approaches) with 2 or more lanes 600*0.70 = 420 vph Minor Street (one approach) with 2 or more lanes 200*0.70 = 140 vph

Warrant No. 1 is not met TIME MAIN STREET (TOTAL OF EB AND WB DIRECTIONS OF TRAFFIC) VPH MINOR STREET APPROACH VPH Warrant Met = Ö Warrant No.1 Volume Crite ria (Major Street = 42 0, Minor Street = 14 ) 7:00 - 8:00 AM 500+780 = 1,280 145 8 :00 9:00 AM 700+620 = 1,320 210 9:00 10:00 AM 300+435 = 735 120 10:00 11:00 AM 385+405 = 790 100 11:00 12:00 PM 450+420 = 870 110 12 00 1:00 PM 470+430 = 900 115 1:00 2:00 PM 280 + 320 = 600 85 Ö Ö 2:00 - 3:00 PM 245+255 = 500 52 3:00 - 4:00 PM 225+325 = 550 50 4:00 - 5:00 PM 680+780 = 1,460 220 Ö 5:00 - 6:00 PM 700+750 = 1,450 205 Ö 6:00 - 7:00 PM 480+480 = 930 155 Ö Warrant No. 1 is not met

Warrant 2: Interruption of Continuous Traffic Warrant Applies where traffic volume on major street is so high that traffic on minor intersecting street experiences excessive delay.

satisfied when, the volumes given in the table exists on the major street on the higher-volume minor street the signal installation will not seriously disrupt progressive traffic flow for each of any 8 hours of an average day when 85th percentile speed of major street exceeds 40 mph 70 % of the requirements may be used

Warrant #2 Requirements (for 8 hours): Can use the 70% reduction, since 85th percentile speed > 40 mph Major Street (total of both approaches) with 2 or more lanes 900*0.70 = 630 vph Minor Street (one approach) with 2 or more lanes 100*0.70 = 70 vph

Warrant No. 2 is met TIME MAIN STREET (TOTAL OF WB AND EB DIRECTIONS OF TRAFFIC) VPH MINOR STREET APPROACH VPH Warrant Met = Ö Warrant No.1 Volume Crite ria (Major Street = 630 0, Minor Street = 70 ) 7:00 - 8:00 AM 500+780 = 1,280 145 8 :00 9:00 AM 700+620 = 1,320 210 9:00 10:00 AM 300+435 = 735 120 10:00 11:00 AM 385+405 = 790 100 11:00 12:00 PM 450+420 = 870 110 12 00 1:00 PM 470+430 = 900 115 1:00 2:00 PM 280 + 320 = 600 85 Ö Ö Ö Ö Ö 2:00 - 3:00 PM 245+255 = 500 52 3:00 - 4:00 PM 225+325 = 550 50 4:00 - 5:00 PM 680+780 = 1,460 220 Ö 5:00 - 6:00 PM 700+750 = 1,450 205 Ö 6:00 - 7:00 PM 480+480 = 930 155 Ö Warrant No. 2 is met

Warrant 8: Combination of Warrants Signals may be justified where no single warrant is satisfied but where Warrants 1 and 2 are satisfied to the extent of 80 percent or more of the stated values Warrant No. 2 is met. Therefore, we don’t need to check Warrant #8 in this particular case.

Warrant 9: Four Hour Volumes Satisfied when, each of any four hours of an average day the plotted points representing the vehicles per hour on the major street (total of both approaches) and the corresponding vehicle per hour on the higher volume minor street approach (one direction only) all fall above the curve in Figure 4-3 for the existing combination of approach lanes

85 percentile speed exceeds 40 mph, the four hour volume requirement is satisfied when the plotted points referred to fall above the curve in figure 4-4 for the existing combination of approaches.

Warrant #9 Requirement (4 hours) Use Figure 4-4 since 85th percentile speed exceeds 40 mph lower threshold volume for a minor street approach with two or more lanes is 80 vph, when the traffic volumes on the major street exceed 875 vph.

Warrant No. 9 is met TIME MAIN STREET (TOTAL OF WB AND EB DIRECTIONS OF TRAFFIC) VPH MINOR STREET APPROACH VPH Warrant Met = Ö Warrant No.1 Volume Crite ria (Major Street = 875 5 Minor Street = 80 ) 7:00 - 8:00 AM 500+780 = 1,280 145 8 :00 9:00 AM 700+620 = 1,320 210 9:00 10:00 AM 300+435 = 735 120 10:00 11:00 AM 385+405 = 790 100 11:00 12:00 PM 450+420 = 870 110 12 00 1:00 PM 470+430 = 900 115 1:00 2:00 PM 280 + 320 = 600 85 Ö Ö Ö 2:00 - 3:00 PM 245+255 = 500 52 3:00 - 4:00 PM 225+325 = 550 50 4:00 - 5:00 PM 680+780 = 1,460 220 Ö 5:00 - 6:00 PM 700+750 = 1,450 205 Ö 6:00 - 7:00 PM 480+480 = 930 155 Ö Warrant No. 9 is met

Warrant 11: Peak Hour Volume Satisfied when, the plotted point representing the vph the major street (total of both approaches) and the corresponding vehicles per hour of the higher volume minor street approach (one direction only) for one hour of an average day falls above the curve in Figure 4-5 for the existing combination of approach lanes When the 85th percentile speed exceeds 40mph, peak hour volume requirement is satisfied when the plotted point falls above the curve in figure 4-6 for the existing combination of approach lanes

Warrant #11 Requirement (one hour): Use Figure 4-6 since 85th percentile speed of the major street exceeds 40 mph lower threshold volume for a major street approach with two lanes is 100 vph when the major street volume is greater than 1200 vph.

Warrant No. 11 is met TIME MAIN STREET (TOTAL OF WB AND EB DIRECTIONS OF TRAFFIC) VPH MINOR STREET APPROACH VPH Warrant Met = Ö Warrant No.1 Volume Crite ria (Major Street = 1200 0, Minor Street = 100 ) 7:00 - 8:00 AM 500+780 = 1,280 145 8 :00 9:00 AM 700+620 = 1,320 210 9:00 10:00 AM 300+435 = 735 120 10:00 11:00 AM 385+405 = 790 100 11:00 12:00 PM 450+420 = 870 110 12 00 1:00 PM 470+430 = 900 115 1:00 2:00 PM 280 + 320 = 600 85 Ö Ö 2:00 - 3:00 PM 245+255 = 500 52 3:00 - 4:00 PM 225+325 = 550 50 4:00 - 5:00 PM 680+780 = 1,460 220 Ö 5:00 - 6:00 PM 700+750 = 1,450 205 Ö 6:00 - 7:00 PM 480+480 = 930 155 Warrant No. 11 is met

Conclusion Based on the results obtained from the warrant study, installation of signal is recommended at the intersection.

Left-Turn Phasing Warrants at Signalized Intersections Warrants based on accidents 3-5 left-turn crashes/year Main Street Correctable LTHO crashes/year ≥ 4 LTHO crashes/ 2 years ≥ 6 14th Street Collision Diagram for the Intersection of Main Street and 14th Street

NUMBER OF OPPOSING LANES Left-Turn Phasing Warrants at Signalized Intersections (ITE Journal April 1986) Warrants based on volumes product of left turn and opposing volume 2 lane exceeds 30,000-50,0000 4 lane exceeds 50,000-100,000 NUMBER OF OPPOSING LANES PRODUCT 1 ≥ 45,000 2 ≥ 90,000 3 ≥ 135,000

NUMBER OF OPPOSING LANES Warrants based on volumes sum of left turn and opposing volume NUMBER OF OPPOSING LANES SUM 1 ≥ 500 2 ≥ 900 3 ≥ 1000

Example Product Rule: 200*680 = 136,000 For 2 opposing lanes, yes the left-turn phase is warranted (≥ 90,000) Brentwood Street 8 Mile Road WB Thru = 680 vph EB LT = 200 vph Sum Rule: 200+680 = 880 For 2 opposing lanes, the left-turn phase is not warranted (< 900)