Traffic Signal Warrants

Example Problem

Tapan K. Datta, Ph.D., P.E.

Intersection of Main Street and14th 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

Main Street

14th

Str

eet

12-hour Traffic Volumes

TIME MAIN STREET (TOTAL OF EB

AND WB DIRECTION OF TRAFFIC) VPH

MINOR STREET APPROACH 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+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

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 700+750 = 1,450 205

6:00-7:00 PM 480+450 = 930 155

Warrants for Signalized Intersections

Warrant 1: Minimum Vehicular Volume

Number of lanes for movingtraffic at each approach

Vehicles per hour onmajor street

(total of both approaches)

Vehicles per hour on highervolume minor street approach

(one direction only)

Major Street Minor Street

1 1 500 150

2 or more 1 600 150

1 2 or more 500 200

2 or more 2 or more 600 200

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

TIME

MAIN STREET (TOTAL OF EB AND WB

DIRECTIONS OF TRAFFIC) VPH

MINOR STREET APPROACH VPH

Warrant Met = Warrant No.1

Volume Criteria (Major Street = 420, Minor Street = 140)

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

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 700+750 = 1,450 205

6:00-7:00 PM 480+480 = 930 155

Warrant No. 1 is not met

Warrant 2: Interruption of Continuous Traffic

Number of lanes for movingtraffic at each approach

Vehicles per hour onmajor street

(total of both approaches)

Vehicles per hour on highervolume minor street approach

(one direction only)

Major Street Minor Street

1 1 750 752 or more 1 900 75

1 2 or more 750 100

2 or more 2 or more 900 100

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 = Warrant No.1

Volume Criteria (Major Street = 6300, 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

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 700+750 = 1,450 205

6:00-7:00 PM 480+480 = 930 155

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 = Warrant No.1

Volume Criteria (Major Street = 8755 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

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 700+750 = 1,450 205

6:00-7:00 PM 480+480 = 930 155

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 = Warrant No.1

Volume Criteria (Major Street = 12000, 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

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 700+750 = 1,450 205

6:00-7:00 PM 480+480 = 930 155

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 N

LEGENDRear-End

Backed Into

Head On

Angle

Left-TurnHead-On

Sideswipe

Fixed Object

Parked Vehicle

Pedestrian

Other

Injury

Fatality

*

Kal

amaz

oo

Ave

nu

e

Burton street

Collision Diagram for Burton Street and Kalamazoo Avenue from April 1997- March 1998(12 months) before data

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*4

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4142

N

LEGENDRear-End

Backed Into

Head On

Angle

Left-TurnHead-On

Sideswipe

Fixed Object

Parked Vehicle

Pedestrian

Other

Injury

Fatality

**

Kal

amaz

oo

Ave

nu

e

Burton street

Collision Diagram for Burton Street and Kalamazoo Avenue from April 1997- March 1998(12 months) before data

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4142

Correctable LTHO crashes/year ≥ 4 LTHO crashes/ 2 years ≥ 6

Main Street

14

th S

treet

Collision Diagram for the Intersection ofMain Street and 14th Street

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

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 = 136,000For 2 opposing lanes, yes the left-turn phase is warranted (≥ 90,000)

Sum Rule:200+680 = 880For 2 opposing lanes, the left-turn phase is not warranted (< 900)

WB Thru = 680 vph

EB LT = 200 vph

8 Mile Road Bre

ntw

ood

Str

eet