1. CE 7670: Advanced Traffic Signal Systems
Tapan K. Datta, Ph.D., P.E.
Winter 2003

2. Probability of Failure Method
If (x-1) vehicles cross the stop bar during a time equal to G – (K1 + K2) then the average minimum headway between the vehicle is given by:
Avg. Min. headway = time/volume, or
G – K
x-1
Where
K = K1 + K2
K1 = starting delay of the platoon
K2 = time required for last vehicle to cross
G = green plus amber time
D = constant departure headway
x = number of departures
G = (x-1) D + K, or, G = x D + K - D

3. Probability of Failure Method to Calculate Cycle Length

4. Probability of Failure Method to Calculate Cycle Length

5. Assume critical lane volume = V
3600 C
* X
X =
[ G – (K – D)] D
Where:
Sum of hourly critical lane volume (V) for all phases
= total critical lane volume per hour
V =
3600 C
*  X =
 G - (K-D) * D
Where:
C =  G
 = number of phases
K = lost time = K1 + K2
G = green plus amber time
D = constant departure headway
x = number of departures
V =
3600 C *
C - (K-D) D [ ]
= 3600 C CD
3600 (K-D) -

6. Say K = K1+ K2 = 6 sec
D = 2 sec
3600* 3(6-2) 
V (for  = 3) =
1800 -
C* 2
21600 =
1800 - C
3600* 4(6-2) 
V (for  = 4) =
1800 -
C* 2
28800 =
1800 - C
As V approaches 1800 vph, C approaches infinity
C =
3600 (K-D)
3600 – D V
Based on uniform arrival

7. Poisson Arrival Based on random arrivals P (x+1) =   m(x+1) e-m
Where:
m = average arrival per cycle = V
3600/C

8. Signal Phasing Design Through traffic shared with right-turn traffic
Solid green followed by yellow and red
Left-turn traffic: Lead left-turn
Protected
Green left arrow followed by yellow and red
Protected/Permissive
Green left arrow followed by solid green
Then yellow and red

9. Left-turn traffic: Lag left-turn
Permissive/Protected
Solid green followed by green left arrow
Then yellow and red
Split Phasing
When one approach has much higher volume than the opposing approach, only one direction traffic (including left-turn) is allowed to proceed in a protected manner, and then the opposing traffic

10. The Texas Approach
Trap Problem: Using protected-permitted and lead-lag phasing at the same time leads a vehicle to be trapped
Solution: Waiting left-turner is able to see the ball indications which clear at the same time as opposing through traffic, and thus drivers do not make false assumptions

11. The Texas Concept
Having at least two signal heads for through traffic in addition to five-section protected-permitted left-turn signal
Reducing the visibility of circular indications of five-section left-turn signal so that they are readily visible by left-turners
Modifying the restricted-visibility indications so that they continue to display a circular green to left-turners through the opposing left-turn movement’s lagging protected phase, and displaying the amber for the permitted left-turn only when the amber is on for opposing through traffic also

12. The Florida Recommendations
Protected/Permissive left-turn phasing should be provided in all intersection approaches
Protected only left-turn should be provided if:
Double left-turn only lanes are operating
Intersection geometric compels to do so
Poor sight distance to opposing traffic
Speed limit of opposing traffic is higher than 45mph
Number of left-turn head-on crashes exceeds per year

13. The Florida Recommendations
Permissive/Protected left-turn phasing should be limited and restricted to the following situations:
T-intersections where U-turns are prohibited
4-way intersections where the opposing approach has prohibited left-turns or protected only left-turn phasing
4-way intersections where the left-turn volumes from opposing approaches do not substantially differ throughout the various time periods of a normal day

14. The Florida Recommendations
Split phasing can be effectively used when:
Opposing approaches are offset to an extent that simultaneous left-turns from opposing directions would be impossible or hazardous
Left-turn volumes are extremely heavy on opposing approaches and both are nearly equal to the adjacent through movement critical lane volume
Left-turn volume is extremely heavy on an approach that does not include a separate left-turn lane
Drivers are permitted to turn left from more than one lane and also to use right-most left-turn lane as a through lane.

15. The Kentucky Recommendation
Protected/Permissive is the preferable method because of savings in time compared to protected only phasing
Protected/Permissive should not be used if the following conditions exist:
Approach speed > 45mph
Protected only is currently in use and speed limit is over 35 mph
Left-turn movement must cross three or more opposing through lanes
Intersection geometrics force the left-turn lane to have a separate signal head
Double left-turn only lanes on the approach
Left-turn head-on crashes is 4 or more per year
Potential left-turn problem exists documented by a traffic conflict study
A sight distance problem exists

16. Lane Configuration for the Intersection of Gratiot Avenue and 23 Mile Road

17. Future AM Peak Hour Traffic Volumes for Gratiot Avenue and 23 Mile Road
Approach Volume = 1,257vph
23 MILE ROAD
187+10=197
180
726
340+11=351
728+5=733
Approach Volume = 1,295vph
100
361+4= 365
Approach Volume = 651vph
498+6=504 99
298
156+5=161 47
Approach Volume = 558vph
Total Intersection Volume
= 3,761 vph

18. Phasing Plan for Gratiot and 23 Mile Road1 2 3 4 5 6

19. Example 5 x 5 lane road Four phase signal timing plan 380 140 100 100
280
470
940
100
180
180
200
Critical lane volumes
V1 = Max [( )/2, ( )/2] = 480
V2 = Max [180,100] = 180
V3 = Max [( )/2, ( )/2] = 560
V4 = Max [280,100] = 280
760

20. Start by assuming a cycle length Calculate ‘m’ for each phase
Say 90 seconds
Calculate ‘m’ for each phase V
3600/C m=
m1=
480
3600/90
= 12
m2=
180
3600/90
= 4.5
m3=
560
3600/90
= 14
m4=
280
3600/90
= 7

21. Phase length ‘G’ for various % of failure
Use Figure 7-3 to find the phase length ‘G’ for various percentages of failure  m
Phase length ‘G’ for various % of failure 2 5 20 30 40 1 12 42 39 33 28
4.5 21 19 15 14 13 3 47 44 37 35 4 7 29 26 18
TOTAL CL
139
128
106 98 92

23. If the arrivals of cars are random
Cycle length of 98 seconds has 30% of failure
Cycle length of 92 seconds has 40% failure

24. Now assume a 100-second cycle length
Calculate ‘m’ for each phase V
3600/C m=
m1=
480
3600/100
= 13.3
m2=
180
3600/100
= 5.0
m3=
560
3600/100
= 15.6
m4=
280
3600/100
= 7.8

25. Phase length ‘G’ for various % of failure
Use Figure 7-3 to find the phase length ‘G’ for various percentages of failure  m
Phase length ‘G’ for various % of failure 2 5 20 30 40 1
13.3 44 41 35 33 31
5.0 23 21 17 15 14 3
15.6 51 48 37 4
7.8 29
TOTAL CL
149
139
116
106
100

27. If the arrivals of cars are random
Cycle length of 106 seconds has 30% of failure
Cycle length of 100 seconds has 40% failure

28. Comprehensive Example: Intersection of Rochester Road and E
Comprehensive Example: Intersection of Rochester Road and E. Wattles Road, Troy Michigan

29. SPEED LIMIT 45 Sign N
Blockbuster
Video Store
Papa
Romano’s
Pizza
Ridley’s
Bakery
Cafe
ONLY
38’
Merchant of
Vino Beverage
Outlet
RIGHT LANE MUST
TURN RIGHT Sign
ONLY
Kinko’s
Copy Center
Accent
Florist
173’
ROCHESTER ROAD
ONLY
Comerica Bank
ONLY
NO TURN ON
RED Sign
RIGHT LANE MUST
TURN RIGHT Sign
NO TURN ON
RED Sign
12’
12’
12’
12’
13’
13’
SPEED LIMIT
40 Sign 9’ 6’
24’
65’
138’
22’
41’ 3’
12’
ONLY
ONLY
19’
14’
ONLY
12’
11’
ONLY
ONLY
ONLY
13’
17’
ONLY
12’
ONLY
43’
E. WATTLES ROAD
Street Name Signs
SPEED LIMIT
40 Sign
NO TURN ON
RED Sign
75’
176’ 7’ 8’
34’ 8’
RIGHT LANE MUST
TURN RIGHT Sign
NO TURN ON
RED Sign
ONLY
Pavement markings
very faded
108’
Shell
Gasoline
Station
ONLY
TO I-75 Sign
Wendy’s
Restaurant
20’
SPEED LIMIT
45 Sign
13’
13’
11’
13’
14’
Condition Diagram for Rochester Road and E. Wattles Road - Troy, Michigan

30. WESTBOUND E. WATTLES ROAD
EASTBOUND E. WATTLES ROAD
NORTHBOUND ROCHESTER ROAD
SOUTHBOUND ROCHESTER ROAD

31. AM Peak 8-9 AM 73
678
109
103
616
150 76
258 70
567
191 N
PM Peak PM
467
554
116
103
1135
300
241
568 90
331
130
Midday Peak Noon- 1 PM 56
497 98 91
855
204
155
225
141 76
242
162
Traffic Volumes for Rochester Road and East Wattles Road - Troy, Michigan

32. Phasing Diagram for Existing Condition
N-S
Through/Right Phase 3 4
N-S
Left-Turn Phase
E-W
Left-Turn Phase 2 1
E-W
Through/Right Phase

33. Capacity Analysis For Existing Traffic Conditions CYCLE APPROACH
INTERSECTION
INTERSECTION
LENGTH
LOS
LOS
DELAY
(SEC)
(SEC/VEH)
Northbound E
100
Southbound D E
48.8
Eastbound F
Westbound C
Northbound E 90
Southbound D E
48.3
Eastbound F
Westbound C
Northbound E 80
Southbound D E
48.4
Eastbound F
Westbound C

34. Crash Data TYPE OFCRASH YEAR AVERAGE NUMBER OF CRASH 1997 1998
CRASHES PER YEAR
Rear-End 46 33
39.5
Angle Intersection 1 2
1.5
Angle Driveway 26 33
29.5
Left-Turn Head-On Inter. 2 3
2.5
Left-Turn Head-On Dway. 2 4 3
Sideswipe 7 6
6.5
Other 3 1 2
INJURIES 15 12
13.5
TOTAL PER YEAR 87 82
84.5

35. LEGEND FOR COLLISION DIAGRAMS
Collision Diagrams for 1997 and 1998
LEGEND FOR COLLISION DIAGRAMS
Rear-End
Backed Into
Head On
Angle
Left-Turn
Head-On
Sideswipe
Fixed Object
Parked Vehicle
Pedestrian
Other
Injury
Fatality *

36. Collision Diagram for Rochester Road and E. Wattles Road for 1997
10/6
4/16
6/28
1/19
9/20
6/20
12/30
12/8
11/12
6/17
2/28
8/29
7/14
12/22 N
Rochester Road
5/23
11/18
3/14
1/17
4/7
7/1
4/23
7/19
10/19
12/2
2/28
5/2
12/20
E. Wattles Road
9/4
1/29
7/8
5/5
2/24
5/15
9/10
5/5
6/3
3/28
7/14
3/29 *
8/24
2/14
4/16
4/7
6/25
6/6
4/12
7/28
5/24
5/17
10/16
1/8
12/19
10/11
1/16
3/9
7/29
10/22
6/10
2/12
5/27
11/1
7/15
5/30
12/9
1/29
9/12
1/30
5/21
9/8
8/15
11/11
8/20
12/30
6/23
4/21
3/15
4/9
5/25
10/16
4/3
3/6
8/2
9/18
9/3
10/29
7/1
8/13
10/23
4/29
Collision Diagram for Rochester Road and E. Wattles Road for 1997

37. Collision Diagram for Rochester Road and E. Wattles Road for 1998
11/20
11/20
4/22
10/17
6/30
6/24
9/15
1/19
6/30 N
Rochester Road
11/9
6/9
1/4
1/30
10/1
2/17
3/27
12/23
3/10
2/27
E. Wattles Road
11/20
3/20
10/8
10/30
9/20
10/2
8/3
9/2
3/19
6/22
6/30
2/23
9/26
6/29
1/17
6/20
9/30
3/3
1/7
6/25
12/10
6/11
5/11
7/9
12/21
7/7
6/11
4/14
5/13
8/10
8/9
7/22
3/29
6/1
5/22
7/17
5/27
11/9
3/27
1/7
7/29
1/2
7/10
3/17
10/3
7/15
4/10
8/30
12/9
6/1
2/11
7/30
12/29
2/14
3/6
10/15
7/15
4/30
8/17
9/29
12/20
10/9
11/26
Collision Diagram for Rochester Road and E. Wattles Road for 1998

38. Phasing Diagram for Modified Signal Timing
Signal Timing Modifications to Existing Traffic Conditions
Include right turn phase with exclusive left turn phase for:
Southbound approach
Eastbound approach
Westbound approach
Phasing Diagram for Modified Signal Timing
E-W
Left-Turn and SB Right Turn Phase 2 4
N-S
Left-Turn and E-W Right Turn Phase
E-W
Through/Right Phase 1
N-S
Through/Right Phase 3

39. Capacity Analysis
For Existing Traffic Conditions with Signal Timing Modifications
CYCLE
APPROACH
APPROACH
INTERSECTION
INTERSECTION
LENGTH
LOS
LOS
DELAY
(SEC)
(SEC/VEH)
Northbound E
100
Southbound D E
47.1
Eastbound F
Westbound C
Northbound E 90
Southbound D E
44.6
Eastbound F
Westbound C
Northbound E 80
Southbound D E
46.9
Eastbound F
Westbound C

40. Cycle length using Webster’s Equation
Existing Condition
y1 = ( )/ (1800 * 2) = or = ( )/ (1800 * 2) = 0.124
y2 = 241/1000 = or = 130/1000 = 0.130
y3 = ( )/(1800 * 2) = 0.40 or = ( )/(1800 * 3) = 0.189
y4 = 103/1000 = or = 116/1000 = 0.116
Y = = 0.945
C = 1.5 * (2 * 4) + 5 / ( ) = 309 second cycle length

41. Calculate Splits 1 split = 0.188 * 90/ 0.945 = 18 sec
Assume Cycle Length = 90 seconds
Split = Green interval + Yellow interval + All-red interval
1 split = * 90/ = 18 sec
2 split = * 90/ = 23 sec
3 split = 0.40 * 90/ = 38 sec
4 split = * 90/ = 11 sec

42. Calculate Clearance Interval
CI = t + v
2(a ± Gg)
w + L +
Speed Limit on Rochester Road = 45 mph = 66 fps
t = 1 sec, a = 10 ft/sec/sec
CINS = /(2 * 10) ( )/ 66
= 4.3 sec sec = 6.3 seconds
Speed Limit on E. Wattles Road = 40 mph = fps
CIEW = /(2 * 10) ( )/ 58.67
= 3.9 sec sec = 6.2 seconds

43. Signal Timing Plan 1 2 3 4
E-W
Through/Right Phase 1
Left-Turn Phase 2
N-S 3 4
G = 12 sec G =18 sec G = 32 sec G = 6 sec
A = 4 sec A = 3 sec A = 4 sec A = 3 sec
R = 74 sec R = 69 sec R = 54 sec R = 81 sec
AR = 2 sec AR = 2 sec AR = 2 sec AR = 2 sec

44. Proposed Improvements
High right turn volume for Northbound Rochester Road
Include exclusive right turn lane using existing pavement width

45. SPEED LIMIT 45 Sign
Papa
Romano’s
Pizza
Ridley’s
Bakery
Cafe
Blockbuster
Video Store N
ONLY
38’
Merchant of
Vino Beverage
Outlet
RIGHT LANE MUST
TURN RIGHT Sign
ONLY
Kinko’s
Copy Center
Accent
Florist
173’
ONLY
ROCHESTER ROAD
Comerica Bank
ONLY
NO TURN ON
RED Sign
RIGHT LANE MUST
TURN RIGHT Sign
NO TURN ON
RED Sign
11’
11’
11’
11’
15’
15’
SPEED LIMIT
40 Sign 9’ 6’
24’
65’
138’
22’
41’ 3’
11’
ONLY
ONLY
11’
11’
11’
10’
11’
ONLY
ONLY
ONLY
ONLY
12’
11’
ONLY
ONLY
11’
11’
E. WATTLES ROAD
43’
Street Name Signs
SPEED LIMIT
40 Sign
NO TURN ON
RED Sign
75’
176’ 7’ 8’
34’ 8’
RIGHT LANE MUST
TURN RIGHT Sign
NO TURN ON
RED Sign
ONLY
ONLY
108’
Shell
Gasoline
Station
RIGHT LANE
MUST TURN
RIGHT Sign
TO I-75 Sign
ONLY
ONLY
Wendy’s
Restaurant
20’
SPEED LIMIT
45 Sign
12’
11’
10’
10’
11’
10’
Proposed Intersection Diagram for Rochester Road and E. Wattles Road - Troy, Michigan

46. Phasing Diagram for Proposed Improvements with Laneage Modification4
N-S
Left-Turn and E-W Right Turn Phase
E-W
Through/Right Phase 1
N-S
Through/Right Phase 3 2
E-W
Left-Turn and N-S Right Turn Phase

47. With Proposed Improvements- Laneage Modifications
Capacity Analysis
With Proposed Improvements- Laneage Modifications
CYCLE
LENGTH
(SEC)
APPROACH
LOS
INTERSECTION
DELAY
(SEC/VEH)
Northbound D
Southbound C
Eastbound E
100
Westbound
32.9 90
38.0 80
39.4

48. Traffic Signal Warrants

49. Engineering studies should be performed
Traffic signals should not be installed unless one or more of the warrants are met
Engineering studies should be performed
and compared with warrants
analysis should consider effects of right turn volumes
proportion subtracted from volumes should be based on engineering judgement

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

51. 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

52. 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.

53. 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

54. Warrant 3: Minimum Pedestrian Volume
Warranted where the pedestrian volume crossing the major intersection or mid-block location during an average day is:
100 or more for each of any four hours, or
190 or more in any one hour
The pedestrian volume of the major street may be reduced as much as 50% of the values given above when predominant pedestrian crossing speed is below 3.5 fps

55. Warrant 4: School Crossing
warranted at an established school crossing when a traffic engineering study of the frequency and adequacy of gaps in a traffic stream shows that the number of adequate gaps in the traffic stream during the period when the children are using the crossing is less than the number of minutes in the same period.
T = F
width of street 4
Where F = Number of children per group (2) 5
( )
A minimum of 50 children should be utilizing the crossing before applying this warrant

56. Warrant 5: Progressive Movement
Warranted in order to maintain proper grouping of vehicles and effectively regulate group speed
The warrant is satisfied when:
on a one-way street or
a street which has predominantly unidirectional traffic
on a two-way street
adjacent signals do not provide the necessary degree of platooning and speed control,and the proposed and adjacent signals could constitute a progressive signal system
Should be based on the 85% speed unless study indicate other speed is more desirable

57. Warrant 6: Accident Experience
This warrant is satisfied when:
Adequate trial of less restrictive remedies with satisfactory observance and enforcement has failed to reduce the accident frequency; and
Five or more reported accidents, of types susceptible to correction by traffic signal control, have occurred within a 12-month period,and
There exists a volume of vehicular and pedestrian traffic not less than 80 percent of the requirements specified in the warrants
Any signal installation will not seriously disrupt progressive traffic now.

60. Warrant 7: Systems Warrant
A major route has one or more of the following characteristics:
It is part of the street or highway system that serves as the principal network for through traffic flow;
It includes rural or suburban highways outside of, entering, or traversing a city;
It appears as a major route on an official plan, such as a major street in a transportation study

61. 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

62. 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

64. 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.

66. Warrant 10: Peak Hour Delay
Satisfied when these conditions exist for one hour of an average weekday
Total delay experienced by traffic on a side street controlled by STOP sign equals or exceeds four vehicle-hours for a one-lane approach and five vehicle-hours for a two-lane approach, and
The volume on the side street approach equals or exceeds 100 vph for one moving lane of traffic or 150 vph for two moving lanes, and
The total entering volume services during the hour equals or exceeds 800 vph for intersection with four (or more) approaches or 650 for intersections with three approaches

67. 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

70. Example: Main Road with existing driveway
12-hour traffic counts
Major Street is Dequindre Road (N-S)
Has 2 NB lanes and 2 SB lanes
Speed limit = 45 mph
85th percentile speed = 47 mph
Minor Street is Beaumont Hospital driveway approach
One right turn lane and one left turn lane

72. Beaumont Hospital and the proposed signal location at the driveway
On Dequindre Road South of driveway

73. 12-hour Traffic Volumes

74. 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

75. Warrant No. 1 is not met

76. 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

77. Warrant No. 2 is met

78. 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.

79. Warrant No. 9 is met

80. 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.

81. Warrant No. 11 is met

82. Example: Existing Road with Proposed Driveway
Proposed developments may want a traffic signal installed at a driveway location
Traffic impact analysis using ITE “Trip Generation” manual
Provides rates to predict number of trips generated by development
Provides rates only for peak hours
On this basis, only Warrant No. 11 (Peak Hour Volumes) is applicable

83. However, for Shopping Center Developments
ITE published hourly percentages (12 hours) for variation in traffic throughout:
Typical weekday
Typical weekend days
The rates can be used to predict traffic for a twelve hour period
Can perform a warrant study based on other warrants, instead of only Warrant No. 11

85. For example:
Number of trips predicted exiting the driveway approach during the PM peak hour (5-6 PM) = 214 vph
Table 1 shows that from 5-6 PM
The % of exiting traffic = 11%
Use this proportion, along with the percent exiting trips for the remaining hours of the day
To calculate the predicted # of exiting trips for the rest of the day

86. The percent of exiting trips at 10-11 AM is 6.5%
Average weekday
< 100,000 sq. ft. of GLA
Thus, the predicted # of exiting trips (x10-11) will be
214 11
Thus, X10-11 = 126 vph
6.5 =
X10-11

87. Similarly, for the remaining hours:
214 11
Thus, X11-12 = 163 vph
8.4 =
X11-12
214 11
Thus, X12-1 = 160 vph
8.2 =
X12-1
214 11
Thus, X1-2 = 146 vph
7.5 =
X1-2
And so on. Results shown in following table

88. 9:00- 10:00 PM

89. Now, perform a warrant analysis
12-hour traffic counts on major road and predicted 12-hour volumes for driveway approach
Major Street is M-29 Road (E-W)
Has 1EB lane and 1 WB lane with proposed center lane for left turns
Speed limit = 45 mph
Minor Street is proposed retail center driveway approach
Two lanes

90. Proposed signal location for commercial development , across from existing driveway
Existing driveway and M-29

91. 12-hour traffic volumes
(Existing volumes on major street and predicted volumes on minor street)

92. Warrant #1 is met

93. Warrant #2 is met

94. Warrant #9 is met

95. Warrant # 11is not met Volumes on the major street do not meet requirements

96. Left-Turn Phasing Warrants at Signalized Intersections
Warrants based on accidents
3-5 left-turn crashes/year
Correctable LTHO crashes/year ≥ 4
LTHO crashes/ 2 years ≥ 6

97. 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

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

99. Example Product Rule: 180 * 590 = 106,200
For 2 opposing lanes, yes the left-turn phase is warranted (≥ 90,000)
180 vph
590 vph
Sum Rule:
= 770
For 2 opposing lanes, the left-turn phase is not warranted (< 900)

100. minimum left-turn hourly volumes- minimum left-turn volume per cycle
exceeds 125 vph
minimum left-turn volume per cycle
exceeds 2 vehicles/cycle

101. Delay Analysis Maximum Allowable delay = 96 sec/veh OR
minimum total delay = 1.5 vehicle-hours

102. Other warrants geometric design- sight distance inadequate
signal system- progressive movement/adjacent intersection phasing
traffic conflict- exceeds 10-14/hour
approach speed- of opposing traffic exceeds 45 mph