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

2. 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

3. 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
= 1,280
145
8:00 -
9:00 AM
= 1,320
210
9:00 -
10:00 AM
300+43
5 = 735
120
10:00 -
11:00 AM
= 790
100
11:00 -
12:00 PM
= 870
110
12:00 -
1:00 PM
= 900
115
1:00 -
2:00 PM
= 600 85
2:00 -
3:00 PM
= 500 52
3:00 -
4:00 PM
= 550 50
4:00 -
5:00 PM
= 1,460
220
5:00 -
6:00 PM 70
0+750 = 1,450
205
6:00 -
7:00 PM
= 930
155

4. Warrants for Signalized Intersections
Warrant 1: Minimum Vehicular Volume

5. 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

6. 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

7. 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
= 1,280
145 8
:00
9:00 AM
= 1,320
210
9:00
10:00 AM
= 735
120
10:00
11:00 AM
= 790
100
11:00
12:00 PM
= 870
110 12 00
1:00 PM
= 900
115
1:00
2:00 PM =
600 85 Ö Ö
2:00 -
3:00 PM
= 500 52
3:00 -
4:00 PM
= 550 50
4:00 -
5:00 PM
= 1,460
220 Ö
5:00 -
6:00 PM
= 1,450
205 Ö
6:00 -
7:00 PM
= 930
155 Ö
Warrant No. 1 is not met

8. 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.

9. 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

10. 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

11. 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
= 1,280
145 8
:00
9:00 AM
= 1,320
210
9:00
10:00 AM
= 735
120
10:00
11:00 AM
= 790
100
11:00
12:00 PM
= 870
110 12 00
1:00 PM
= 900
115
1:00
2:00 PM =
600 85 Ö Ö Ö Ö Ö
2:00 -
3:00 PM
= 500 52
3:00 -
4:00 PM
= 550 50
4:00 -
5:00 PM
= 1,460
220 Ö
5:00 -
6:00 PM
= 1,450
205 Ö
6:00 -
7:00 PM
= 930
155 Ö
Warrant No. 2 is met

12. 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.

13. 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

15. 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.

17. 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.

18. 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
= 1,280
145 8
:00
9:00 AM
= 1,320
210
9:00
10:00 AM
= 735
120
10:00
11:00 AM
= 790
100
11:00
12:00 PM
= 870
110 12 00
1:00 PM
= 900
115
1:00
2:00 PM =
600 85 Ö Ö Ö
2:00 -
3:00 PM
= 500 52
3:00 -
4:00 PM
= 550 50
4:00 -
5:00 PM
= 1,460
220 Ö
5:00 -
6:00 PM
= 1,450
205 Ö
6:00 -
7:00 PM
= 930
155 Ö
Warrant No. 9 is met

19. 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

22. 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.

23. 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
= 1,280
145 8
:00
9:00 AM
= 1,320
210
9:00
10:00 AM
= 735
120
10:00
11:00 AM
= 790
100
11:00
12:00 PM
= 870
110 12 00
1:00 PM
= 900
115
1:00
2:00 PM =
600 85 Ö Ö
2:00 -
3:00 PM
= 500 52
3:00 -
4:00 PM
= 550 50
4:00 -
5:00 PM
= 1,460
220 Ö
5:00 -
6:00 PM
= 1,450
205 Ö
6:00 -
7:00 PM
= 930
155
Warrant No. 11 is met

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

25. 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

26. 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
NUMBER OF OPPOSING LANES
PRODUCT 1
≥ 45,000 2
≥ 90,000 3
≥ 135,000

27. 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

28. 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:
= 880
For 2 opposing lanes, the left-turn phase is not warranted (< 900)