TR9301-SY 911001TRAFFIC SIGNAL
WARRANT STUDIES
MacArthur Blvd. and Samuel Blvd.
Bethel Road and Coppell Road
Prepared for:
The City of Coppell
Coppell, Texas
Prepared by:
Barton-Aschman Associates, Inc.
Dallas, Texas
TRAFFIC SIGNAL
WARRANT STUDIES
MacArthur Blvd. and Samuel Blvd.
Bethel Road and Coppell Road
Prepared for:
The City of Coppell
Coppell, Texas
Prepared by:
Barton-Aschman Associates, Inc.
Dallas, Texas
October, 1991
TABLE OF CONTENTS
PAGE
List of Tables and Figures ............................................ ii
1. Introduction ............................................... 1-1
Purpose ............................................ 1-1
Study Procedure ...................................... 1-1
2. MacArthur Blvd. and Samuel Blvd ................................ 2-1
Intersection Characteristics ............................... 2-1
Data Collection ....................................... 2-1
Signal Warrant Analysis ................................. 2-1
Operations Analysis .................................... 2-1
Conclusions .......................................... 2-6
3. Bethel Road and Coppell Road .................................. 3-1
Intersection Characteristics ............................... 3-1
Data Collection ....................................... 3-1
Signal Warrant Analysis ................................. 3-1
Operations Analysis .................................... 3-1
Conclusions .......................................... 3-6
2.1
2.2
3.1
3.2
1.1
2.1
2.2
3.1
3.2
LIST OF TABLES
PAGE
Existing Traffic Volumes
MacArthur Blvd. and Samuel Blvd ........................... 2-3
Summary of Signal Warrant Analysis ............................. 2-5
Existing Traffic Volumes
Bethel Road and Coppell Road ............................. 3-3
Summary of Signal Warrant Analysis ............................. 3-5
LIST OF FIGURES
PAGE
Study Locations ............................................ 1-2
Existing Conditions
MacArthur Blvd. at Samuel Blvd./Village Dr .................... 2-2
Turning Movement Counts - P.M. Peak Hour ....................... 2-4
Existing Conditions
Bethel Road at Coppell Road .............................. 3-2
Turning Movement Counts - P.M. Peak Hour ........................ 3-4
Section 1
Introduction
Section 1
Introduction
The City of Coppell has various unsignalized intersections within the City that have
experienced increased traffic demands and associated operational problems over the years.
The City recognizes the potential for improving intersection operations at these locations
through signalization based upon an engineering and traffic investigation.
PURPOSE
This study was conducted to assist the City of Coppell in determining the need for traffic
signalization at two (2) locations. The study locations are shown in Figure 1.
STUDY PROCEDURE
Section 4C, "Warrants", of the Texas Manual on Uniform Traffic Control Devices (TMUTCD)
was used as a guide for conducting these studies. This Manual details a comprehensive
investigation of traffic conditions and physical characteristics of the study location that are
required to determine the need for signalization.
The TMUTCD points out the following in regard to warrants for traffic signal installation:
"Traffic control signals should not be installed unless one or more of the signal
warrants in this Manual are met. Information should be obtained by means of
engineering studies and compared with the requirements set forth in the
warrants. If these requirements are not met, a traffic signal should neither be
put into operation nor continued in operation (if already installed)."
In addition to evaluating the warranting requirements as outlined by the TMUTCD, each study
location was analyzed to determine intersection levels of service. Level of service (LOS) is
a qualitative measure to identify how effective traffic is accommodated at an intersection by
categories A through F. Level of service A corresponds to very light traffic with little or no
delays and F corresponds to extremely heavy traffic and long delays and congestion. Level
of service C-D is generally considered to be acceptable during peak traffic flow periods.
1-1
I I I I I I I I I
---- ,/"~.---"--% (~ MeoArthur Blvd. and Samuel Blvd.
~ /// _ I~"':~L~ (~ Bethel Rd. and Compel, Rd.
· ~~...~ -- .: ~ . ~
' ~.X.w'~''' ~
.or ,:s'. ~~ .i Ha.kb~ STUDY'LOCATIONS
'~~~ copPelI, -Texas
,, , ,
The methodology used in this study for determining level of service is outlined in Chapters 9
and 10 of the TRB Special Report 209, 1985 Highway Capacity Manual and the
Transportation Research Interim Circular Number 373, "Materials on Unsignalized Intersection
Capacity".
The following tasks were accomplished as part of this study:
A field survey of the sites was made to examine the physical and operational aspects
of the intersections.
2. Existing condition diagrams were developed for each intersection.
Twenty-four hour traffic volume counts were conducted on each of the approaches of
the study intersections to determine traffic magnitudes and variations over the day.
..
Turning movement counts of critical peaks were made to determine special control
considerations, i.e., pedestrians, trucks, left turns, queuing problems.
Traffic accident data for the 12-month period, August 1990 through August 1991,
was obtained from the Coppell Police Department.
Eighty-five percentile (85th %) speeds were estimated by driving with the existing
traffic using a "floating-car" method.
Each intersection was evaluated to determine whether traffic conditions warranted
signal control on the basis of TMUTCD Section 4C.
8. An intersection operations analysis was conducted for each study location.
9. A report of the study findings was prepared.
1-3
Section 2
MacArthur Blvd. and Samuel Blvd.
Section 2
MacArthur Blvd. and Samuel Blvd.
INTERSECTION CHARACTERISTICS
The intersection of MacArthur Blvd. and Samuel Blvd./Village Dr. is located in northeast
Coppell. MacArthur Blvd. is a major arterial with a four-lane divided cross-section and Samuel
Blvd. is a four-lane facility that provides access to the surrounding residential areas.
Intersection control includes stop signs on the Samuel Blvd./Village Dr. approaches. Sight
distance for the Village Dr. approach is restricted due to the horizontal curve of MacArthur
Blvd. and the brick wall between MacArthur Blvd. and the residential area. A diagram of
existing conditions is shown in Figure 2.1.
DATA COLLECTION
Twenty-four (24) hour traffic volume counts were conducted on each of the approaches at
the study location. These counts are summarized in Table 2.1. Critical peak hour (PM peak)
turning movement counts were also made and are presented in Figure 2.2. Accident data
provided by the Coppell Police Department indicated no reported accidents for the analysis
period August 1990 through August 1991.
SIGNAL WARRANT ANALYSIS
An evaluation of the existing traffic conditions and physical characteristics of the study
location was performed to determine the need for signalization based on warranting
requirements presented by the TMUTCD. An intersection is warranted for signalization if one
or more of the signal warrants are met. The intersection of Mac Arthur Blvd. and Samuel
Blvd. meets the requirements of Warrant 11 - Peak Hour Volume. Table 2.2 shows the results
of the signal warrant analysis. The analysis sheets and warranting requirements are included
in the Appendix.
OPERATIONS ANALYSIS
The results of the capacity analysis indicated that the study intersection currently operates
at LOS B under existing conditions and would be expected to operate at LOS A under traffic
signal control. All capacity analyses are based on the PM peak hour traffic volumes. Field
observations made during peak traffic flow periods pointed out that the cross street, Samuel
Blvd.Nillage Dr., often experiences delay due to the relatively heavy volumes and the
horizontal curve that exist on MacArthur Blvd.
2-1
Not to Scale
Samuel Blvd.
No Pavement Markings
Brick Peve~
Bhr. k pev~m
Keep ~ight $
Open Field
Res.
Sidewalk
Villa
No Pavement Markinga
Sidewalk
Res.
FIGURE 2.1
EXISTING CONDITIONS
MacArthur Blvd. at Samuel Blvd./Village Dr.
2-2
TABLE 2.1
EXISTING TRAFFIC VOLUMES
MacARTHUR BLVD. AND SAMUEL BLVD.
MacArthur Blvd. Samuel Blvd.
Time Northbound Southbound Eastbound Westbound
12 AM 4 10 · 6 2
I 6 4 0 1
2 2 2 2 0
3 4 3 1 0
4 2 5 6 2
5 6 12 7 1
6 26 159 48 21
7 80 815 191 64
8 82 262 97 54
9 66 85 61 23
10 62 74 63 20
11 71 89 59 24
12 PM 77 109 84 14
I 79 119 71 14
2 67 125 79 10
3 114 130 75 15
4 165 144 112 16
5 391 228 147 25
6 249 187 138 35
7 137 171 100 21
8 82 137 82 15
9 63 80 66 10
10 46 38 29 9
11 22 19 4 2
24-HOUR TOTAL 1,903 3,007 1,528 398
2-3
Not to Scale
samuel Blvd.
67_~'
24--,-
28--~
Date: 10-3-91
Time: 5:00-6:00 P.M.
C)(~K)
2-4
Village Dr.
FIGURE 2.2
TURNING MOVEMENT COUNTS
P.M. PEAK HOUR /
TABLE 2.2
SUMMARY OF SIGNAL WARRANT ANALYSIS
Warrant
1. Minimum Vehicular Volume
2. Interruption of Continuous Traffic
3. Minimum Pedestrian Volume
4. School Crossing
Meets Requirements
No
No
NA
NA
5. Progressive Movement No
6. Accident Experience No
7. System Warrant No
8. Combination of Warrants No
9. Four Hour Volumes No
10. Peak Hour Delay NA
1 1. Peak Hour Volume
1 2. Traffic Actuated Signals
Yes
No
2-5
CONCLUSIONS
Although the intersection of MacArthur Blvd. and Samuel Blvd.Nillage Dr. does not experience
an accident problem, the existing intersection traffic conditions meets the requirements for
traffic signalization (Warrant I l-Peak Hour Volume) due to the magnitude of intersecting
traffic volumes during peak hour periods and the high approach speeds .that exist on
MacArthur Blvd. Field observations also pointed out that the Village Dr. traffic often
experiences delay and some difficulty in crossing or accessing MacArthur Blvd. during peak
flow periods due to the restricted sight distance..
Traffic levels at the study intersection are expected to increase due to area growth and
development as evident by the opening of MacArthur Blvd. to the north. Accidents at the
study intersection should be monitored closely since a large percentage of the accident
analysis period for this study was prior to the opening of MacArthur Blvd.
2-6
Section 3
Bethel Road and Coppell Road
Section 3
Bethel Road and Coppell Road
INTERSECTION CHARACTERISTICS
The intersection of Bethel Road and Coppell Road is located in southwest Coppell, west of
Denton Tap Road. At this location both streets are two-lane roadways with 30 mph posted
speed limits. The intersection, a "T" intersection, is currently controlled by an all-way stop
operation. A diagram of existing conditions is shown in Figure 3.1.
DATA COLLECTION
Twenty-four (24) hour traffic volume counts were conducted on each of the approaches at
the study location. These counts are summarized in Table 3.1. Critical peak hour (PM peak)
turning movement counts were also made and are presented in Figure 3.2. Accident records
obtained from the Coppell Police Department indicated no accidents were reported at this
location during the study period August 1990 through August 1991.
SIGNAL WARRANT ANALYSIS
An evaluation of the existing traffic conditions and physical characteristics of the study
location was performed to determine the need for signalization based on the warranting
requirements presented by the TMUTCD. An intersection is warranted for signalization if one
or more of the signal warrants are met. The intersection of Bethel Road and Coppel Road
meets the requirements of Warrant Number 11, Peak Hour Volume, for signalization. Table
3.2 presents the results of the signal warrant analysis. The analysis sheets and warranting
requirements are included in the Appendix.
OPERATIONS ANALYSIS
An operations analySis was performed for the study location for the existing conditions, all-
way stop control, and also for a traffic signal operation. Although the intersection operates
at a good level of service (LOS B) under both control conditions, the average delay per vehicle
is lower under traffic signal control. The number of vehicle stops experienced at the
intersection are also expected to be reduced. Field obsrvations confirmed the delay
experienced at the intersection due to the limited roadway capacity and magnitude of
intersecting traffic volumes.
3-1
I
Not to Scale
"130 MPH
Church
il
Fire Station
Senior Center
Barber Shop
0
0
Bethel Rd.
8top ~
Rea.
Textco
Bt&tion
Rea.
0
FIGURE 3.1
EXISTING' CONDITIONS
Bethel Rd. at Coppell Rd.
TABLE 3.1
EXISTING TRAFFIC VOLUMES
BETHEL ROAD AND COPPELL ROAD
Coppell Road Bethel Road
Time Southbound Eastbound Westbound
12 AM 10 17 13
I 7 8 7
2 16 19 16
3 5 7 10
4 12 9 10
5 36 29 31
6 172 92 129
7 491 262 339
8 ~ 289 181 265
9 169 82 142
10 114 70 124
11 149 132 149
12 PM 133 166 182
1 102 168 135
2 95 161 128
3 62 174 124
4 105 384 145
5 131 663 223
6 88 358 156
7 54 201 117
8 42 123 69
9 42 122 61
10 28 81 44
11 15 37 24
24-HOUR TOTAL 2,367 3,546 2,643
3-3
Not to Scale
~'--76
-~--156
Bethel Rd.
366 -~'
285 ~
Dete: 10-8-91
Time: 5:00-6:00 P.M.
3-4
FIGURE 8.2
TURNING MOVEMENT COUNTS
P.M. PEAK HOUR
TABLE 3.2
SUMMARY OF SIGNAL WARRANT ANALYSIS ~
Warrant Meets Requirements
1. Minimum Vehicular Volume No
2. Interruption of Continuous Traffic No
3. Minimum Pedestrian Volume NA
4. School Crossing NA
5. Progressive Movement No
6. Accident Experience No
7. System Warrant No
8. Combination of Warrants No
9. Four Hour Volumes No
10. Peak Hour Delay NA
1 1. Peak Hour Volume Yes
1 2. Traffic Actuated Signals No
3-5
CONCLUSIONS
The existing traffic conditions and intersection characteristics at the intersection of Bethel
Road and Coppell Road warrants traffic signalization based on the requirements of Warrant
II - Peak Hour Volume of the TMUTCD. This is a result of the relatively high intersecting
traffic volumes during peak hours and the limited roadway capacity that exists at the
intersection.
3-6
APPENDIX
County
City:
TRAFFIC SURVEY - COUNT ANALYSIS
1980 MUTCD WARPOkNTS (Rev. 4)
Population: ~ Survey Date:
Dist. No~
m
~aj Or
Minor
Control
.. Section 85% Speed
Eight l[igh Hours: Lowest. Volume bf. 8 hour's~udy'is the 8th highest hour.
Hajor and minor 8th high hours may not be the same h~ur.
Major Street MAnor Street·
Time Both Approaches High Vol. App.
Ends Vehicles Peds. Vehicles Peds :'
/ of . //Z .
Comments
Warrant 1:
Minimum'Vehicular Volume
Number of Lane~
Major Minor
Street , Street
i 1
2 or · 1
2 or · 2 or >'
1 2 or >
Major St.-~oth. Approaches
8th Highest Hour
Required Existing
Urban Rural, ,. ~Z-. %
500 350
600 -'420
600 ' 2o ·
5O0 35O
Minor-St.-High Vol. Appr.
8th Highest Hour
Required Ex~ng
-Urban ~ural
150 105
150 105
200 14or"
200' 140
warran,t 2.:
Number of Lanes
Haj or Minor
Street Street
1 1
2 or > 1
2 or> 2 or>
1
Interruption of Continuous Traffic
Major St.-Both Approaches
8th Highest Hour
Required
Urban Rural
-750 525
900 630
900 V~30
750 525
Minor'St.-High Vol. Appr.
8th Highest Hour
E~%' Required~ "Existing
· Urban R~r~l ~ %
75 52
75 52
~0o 70/ ~
100 70
Warrant 3: ~inimum Pedestrian Volume A//+
Major Street Traffic - Both Approaches
· 8th Highest Hour
Required R~q.'w/ 4' Med. .Existing
Urban Rural Urban Rural %
600 420 1000 700
Ped. X~WalkACross Maj.
8th Highest Hour
Required Existing
Urban Rural.
150.
Warrant 4:-. School Crossing ...... .:..% ..''. .... ~-, ~
Is the number of adequate gaps in the traffic stream during
Yes' .No the period when the children are using the crossing less
than. the .number of minu'tes An the same period? '~
Warrant 5:
Yes ~o
Yes
Progressive ~ovement
Are the adjacent'signals.in a signal system?
W°.B1d the resultant spacing'.be 1000 feet or more?
Warrant 6: Yes ~
Yes (~
Accident Experience "°"
Is 80% or more of one of'W~rrants ~1, ~2,, or ~3 met?,.
Have. there been more than five accidents suscepti'bie
correction by a traffic Signal in 12 months? '
Warrant 7:
Yes ~
Systems Warrant
Is the peak hour (or each of fi~e hours on weekend)
entering traffic volume on~ all approaches, greater %hen ~007
Check applicable characteristics of each route.
Major Street 1 . 2 . 3 4 . 5
Minor Street i 2
Definition of Characteristics
®
traversing a..city. -'.- .
4.~ It has surface street freeway or expressway ramp· terminals.
5. It appears as ~ major route on an official plan such as a
~.street Plan An an urban area'traffic ,and transportation study.
Warrant~Combination of Warrants ...
Yes __~ Are 80% or.more cf.two of Warrants #1, ~2, or ~3 met?
It is part of.street or highway, system that serves as the principal
network for through traffic.
It connects aFeas of principal traffic generation.
It includes...rural or suburban highways outside, entering cr
maj or
(Attach Supplemental'Sheets)
Other W~ants
Yes
Warrant 9:
Warrant 10:
Warrant 11:
Warrant 12:
Four. Hour-Volumes
Peak-.Hour Delay
Peak Hour Volume
Traffic Actuated Signals
Remarks
0 W
Z ~
-- ~
~: ,..J
0
(COMMUN I TY
4OO
LESS THAN I0,000 POPULATION OR ABOVE 40 MPH ON MAJOR STREET)
OR MORE LANES ~ 2 OR MORE LANES
~~ / 2 OR MORE LANES ~ I LANE
3'00
20O
I00
200
300 400 500 600 700 800 900
I000
MAJOR STREET - TOTAL OF BOTH APPROACHES - VPH
" 80 VPH "" .60 VPH
0 W
Z ~
5OO
400
300
200
I00
WARRAN~ 9
VOLUME
~' --- 2 OR MORE LANES ~ 2 OR MORE LANES
:300 400 500. 600 700 800 900 1000 I I00 1200 I :300 140C
MAJOR STREET - TOTAL OF BOTH APPROACHES - VPH
I ' '1 l
WARI{ANT 11
i,i
u
0
WARRANT
(COMMUN I TY
400
~00
200
I00
LESS THAN I0,.000 POPULATION OR ABOVE 40 MPH ON MAJOR STREET)
/
/ 2 OR MORE LANES B~ Z OR MORE LANES
/
~ ~ ,,,. /2 OR MORE LANES B~ I LANE
300
400 500 600 700 800 900 1000 I I00 1200 1300
MAJOR STREET
- TOTAL OF BOTH APPROACHES
I00 VPH "" 75 VPH
- VPH
WAMMANT
I
._
I
m 500
m 400
om 300
o 200
I
x~ 2 OR MORE LANES E 2 oR MORE'LANES
~ .. ~ '~ /2 OR MORE LANES ~" LANE
'"~'~_ '"'b~: ~__~~.. /I L.ANE~ , LANE
400 600 800 1000 1200. 1400 1600 1800
MAdOR STREET - TOTAL OF BOTH APPROACHES
,' I'~0 VPH ,'', I0~ VPH
- VPH
600
',-' 500
I
:z: 400
~o~
~.~ 200
0
'" I00
WA~II~ANT ¥@LU~ES F@~
~.i ~..
2 LANES
/ 2 LANES ' ' m ' '
2 LANES ~ ...~ ~
~ L,.ES ~ ~ ~~~
~ ~~ ~ RURAL
I LANE ~ I LANE
,,I, I I ~ "
300 400 500 600 700 800 900. I000 I I O0 1200 1300 1400 1500
MAJOR STREET - TOTAL OF BOTH APPROACHES - VPH
0
i,i
::3
_J
0
-r
4OO
300
200
I00
WA~RAIqT 12
WAR ANT Y@L JI E$ ]FOR
J I
· 2 LANES 8~ ,,
V' 2 LANES
2, LANES Bt ~. / '
-- 2 LANES ~ ......
LANES
~ I LANE
'--,. ~"~ ~ ~ /~ -... ;' LANE' Bt i' LANE
2~ LANES ~ ~ ~ "~'"' --.....~~ '~.-~..~
I LANE
I LANE 8~ I LANE "'~'-'----- ~--RURAL
.... I ~ ~ ~ I
200 ::300 400 500 600 700 800 900 I OOI
MAJOR STREET - TOTAL OF BOTH APPROACHES - VPH
I : .J .... J ~ .... J : J : .... J ' ..1 L.,~.J LJ '~_J ',._J :_J , J .l
County:~~-~
City:
TRAFFIC SURVEY - COUNT ANALYSIS
1980 MUTCD WARRANTS (Rev. 4)
Minor
Dist. No____
su ey Date:
Control.. Section 85% Speed
Eight High Hours: Lowest. Volume 0f. 8 hour-s~udy'ts the 8th highest hour.
Major and minor 8th high hours may not be the same h~ur.
Time
Ends
Major Street
Both Approaches
Vehicles Peds.
Minor Street.
High Vol. App:
Vehicles Peds ."
I 1' o
Comments
Warrant 1:
Minimum'Vehicular Volume
Number of Lane~ Major St.-~oth. Approaches
8th H~ghest Hour
Major. Minor Required
Street , Street Urban Rural,
I I ~00 350
2 or > i 600 .-~420
2 or > 2 or >' 600 '420
1 2 or > 500 3§0~
warran~ 2:
Number of Lanes
Minor. St.-High Vol. ApDr.
8th ~ighest Hour
Exi~i~g~ Required ~
Existing
,~ % 'Urban _.Rural ', 150 .~ '105
150 105
200 140
200' 140
~4aj or Minor
Street Street ~ban Rural
1 I V75'0 525
2 or > 1 900 630
2 or > 2 or · 900 '630
1 2 or · 750 525
Intekkuption of continuous Traffic
Major St.-Both Approaches Minor'St.-High Vol. Appr.
8th Highest ~our .Sth Highest Hour
Required Existing Required.~ ~xisting
//% Urban Rural
%
W5 52
75 52
. 100 70
100 70
Warrant ~: ~inimum Pedestrian Volume
Major Street Traffic - Both Approaches
8th Highest Hour :
Required Req.'w/ 4' Medj .EXisting
Urban Rural Urban Rural %
600 420 1000 700
Ped. X-Walk.Across Maj.
8th'Highest Hour
Required Existing
Urban Rural %
150 105~
Warrant 4:--School Crossing' ~f~.a~ ..... ~..,
Is the number dequate gaps in the traffic, str. eam during ~
Yes' -No the period when the children are using the crossing less
than the :number of minutes in the same period?
Warrant
Yes
Yes No
Progressive ~ovement
Are the adJacent'slg~als.in.a signal system?
Would.~. the resultant spacing.be 1000 feet or more?
Warrant,~ Accident Experience
Yes ~ Is 80% or more of of'Warra.nt'S'!~~, or ~3 met?
correction by a traffic signal in 12 months? -
Warrant
Yes .~
Major Street
Minor Street
Systems Warrant -
Is the peak hour (or each of 'five hours on weekend)
entering traffic volume on' all approaches greater than 800?
Check applicable characteristics of each route[~
i . 2 .. 3 ' 4 5
i 2 3 4 5 '' ·
Definition of Chara¢:tAristics
1. It is part of.street or highway, system that serves as the principal
network for through traffic.
2. It connects areas of principal traffic generation.
3. It includes...rural or suburban highways outside, entering cr
traversing a..city. ..'.. ' ..
4. ~ It has surface street freeway or expressway.ramp terminals.
It appears"as ~& major route on an official plan such as a major
street Plan in an urban area traffic and transportation study.
Warrant~ Combination of Warrants ...
Yes ~ Are 80% or.more of.two of Warrants #1, ~2, or ~3 met?
Otheryes Wa~nts
"Yes ~
(Attach Supplemental'Sheets)
Warrant 9: Four. BourVolumes
Warrant 10: Peak. Hour Delay
Warrant 11: P6ak ~our Volume
Warrant 12: Traffic Actuated Signals
Remarks
WARRAN~ 9
5OO
~,,.~.~...._..--2 OR MORE LANES g~ 2 OR MOIRE LANES
, 400
uJ .~
~ ~o 300
0 tO
z ~ 200
--
0
:]:
300
400 500 600 700 800 900' 1000 I I00 1200 1300 140(
MAdOR STREET - TOTAL OF BOTH APPROACHES - VPH
" 115 VR, H "" 80 VPH
WAR~AH~ 9
o
Z
WAMKANT
(COMMUN I TY
LESS THAN I0,000 POPULATION ,OR ABOVE 40 MPH ON MAJOR STREET)
>.
U
IJJ
400
3'00
2OO
I00
2 OR MORE LANES 8{ 2 OR MORE LANES
'" / 2 OR MORE LANES I~ I LANE
!
200 300 400 500 600 700 800 900 I000
MAJOR STREET - .TOTAL OF BOTH APPROACHES - VPH
, * 80 VPH "" 60 VPH
.__J :._.J ,_J ; .... J ,. ._} ..__J, ...... J i._J ;~ ...... J ;.___} i ...... J ....J
WARRANT Il
WAI I ANT
~ /2 OR MORE LANES E 2 OR MORE LANES
2 OR MORE LANES ~'[ LANE
600
500
400
300
200
100
400
600 800 1000 1200. 1400 1600 1800
MAJOR STREET - TOTAL OF BOTH
- I,:,r) vr:'FI ,, ,, I oo
APPROACHES
VPI-I
- VPH
! 1
WA~ANT
IPIBAK IOILII ¥OLILII Ii WAlk,ANT
(COMMUNITY LESS THAN I0,000 POPULATION OR ABOVE 40 MPH ON MAJOR
STREET)
I..d
400
o 300
Ld
:~ 200
0
m I00
/ 2 OR MORE LANES & 2 OR MORE LANES
~ ''
##
300
400 500 600 700 800 ·900 1000 I I O0 1200 1300
MAJOR STREET - TOTAL
" I00 VPH
OF BOTH APPROACHES
** 75 VPH
- VPH
WAIRRAI{~ '-:12
0 Iai
0
600
5OO
400
300
200
I00
TWO IH[IIC IHIOU S
2 LANES
/ Z LANES . '
LANES ~.... ~~.
· . .- I LANE '_~
~..~'""'~.~~~~ ~ (.,,~ LANE E, ',LANE
2 LANES ~ ~
I LANE ~'~~ ~
~~ ~ RURAL
I LANE ~ I LANE
I I I I "
300 400 500 600 700 800 900. I000 I I00 1200 1300 1400 1500
MAJOR STREET - TOTAL OF BOTH APPROACHES - VPH
WARRAN~-:12
600
2 LANES &
" ,/ 2 LANES" . '"
2 LANES 8<
'.: 2 LANES '~ URBAN 2 LANES
'~~'. " '~~.. ~ ./' LANE
..~ % ~% ~ ,(I LANE ~ I LANE
2LANES ~ ~ ~~ ~'
~ ~ ~ ~ RURAL
I LANE ~ I LANE
I ,I I ....... ~
I
I-- U
zB
0
5OO
400
~00
2OO
!00
300 400 500 600 700 800 900. I000 i I O0 1200 1300 1400 1500
MAJOR STREET - TOTAL OF BOTH APPROACHES - VPH
SECTTON 9 - TRAFFIC SIGI~LS
9.1 INTRODUCTION
A highway traffic signal is any power-operated trafficcontrol device,
other than a barricade warning light or steady burning electric lamp, by
which traffic is warned or directed to take some specific action.
9.1.1 Basis of Installation
In most cases the installation of a highway traffic signal
will operate either to the advantage or disadvantage of the vehicles and
persons controlled. A careful analysis of traffic operations and other
factors at a large number of signalized and unsignalized intersections,
coupled with the judgment of experienced engineers, have provided a series
of warrants that define the nlinimum conditions under which signal
installations may be justified. Consequently the selection and use of this
control device should be preceded by a thorough engineering study of roadway
and traffic conditions.
Engineering studies should be made of operating signals to
determine if the type of installation and the timing program meet the
current requirements of traffic.
9.1.2
Definitions Relating to Signals
The following terms are used throughout Part IV:
1. Signal Face - that part of a highway traffic signal
which controls one or more traffic movements in a single
direction.
2. Signal Head - an assembly of one or more signal faces.
3. Signal Lens - that part of the optical unit which
redirects the light coming directly from the light
source and its reflector, if any.
4. Signal Indication - the illumination of a signal lens or
equivalent device.
9-1
9.1.3 General Aspects
A traffic control signal (traffic signal) is a type of
highway traffic signal by which traffic is alternately directed to stop and
permitted to proceed.
Traffic control signals are sometimes described as either
pretimed or traffic-actuated. Under pretimed control the red, green, and
yellow intervals are predetermined. Under traffic-actuated control, the red
and green intervals are varied continuously according to traffic demands.
The features of traffic control signals in which vehicle
operators and pedestrians are interested are the location, design,
indications, and legal significance of the signals. These are identical for
all types of traffic control signals. Uniformity in the design features
that affect the traffic to be controlled (as set forth in the Manual) is
especially important for safe and efficient traffic operations.
Special police supervision and/or enforcement should be
provided for a new non-intersection location.
9.1.4 Advantm~s, and Dtsadvantages of~,,Traff_lc~,ontr~l ~$tgr~)s~
Traffic control signals are valuable devices for the control
of vehicle and pedestrian traffic. However, because they assign the
right-of-way to the various traffic movements, traffic control signals exert
a profound influence on traffic flow.
Traffic control signals, properly located and operated,
usually have one or more of the following ~d~ntages;'
They can provide for the orderly movement of traffic.
Where proper:physical layouts and control measures are
~used, they can increase the traffi'c-handling capacity of
,the intersection.
They can reduce the frequency of certain types of
accidents, especially the right-angle type.
0
Under favorable conditions, they can be coordinated to
provide for continuous o.r nearly continuous movement of
traffic at a definite speed along a given route.
They can be used to interrupt heavy traffic at intervls
to permit other traffic, vehicular or pedestrian, to
cross.
9-2
Many laymen believe that traffic signals provide the solution
to all traffic problems at intersections. This has led to their
installation at a large number of locations where no legitimate factual
warrant exists.
Traffic signal installations, even though warranted by
traffic and roadway conditions, can be ill-designed, ineffectively placed,
improperly operated, or poorly maintained. The following factors can result
from improper or unwarranted signal installations:
1. Excessive delay may be caused.
2. Disobedience of the signal indications is encouraged.
The use of less adequate routes may be induced in an
attempt to avoid such signals.
Accident frequency (especially the rear-end type) can be
significantly increased.
9.2 DETERMINING NEED
Determining Need for Traffic Signal Control. The first and basic
question that must be addressed is whether or not traffic signalization is
needed. Since traffic signals are considered the most restrictive of the
traditional traffic control devices, they should be used only where the less
restrictive signs or markings do not provide the necessary level of control.
Requests for the installation of traffic signals originate from
numerous sources including:
o General public (individual citizens, citizen groups)
o Government officials
o Industrial and commercial developers and operators
o Media
o Engineering staff of the responsible agency
o Other agencies.
However, it is the responsibility of the traffic engineering agency to
make a decision whether such requests are justified. The decision should be
based on a comprehensive investigation of traffic conditions and location
characteristics. The comprehensive investigation will provide the data
necessary for the design and operation of a traffic control signal that is
found to be justified.
9-3
It is not unusual to find that there are a number of locations where
the minimum warrants are satisfied, but there are not adequate resources
(budget, manpower) to effect immediate installation. Data obtained from
comprehensive field investigations can be used to establish priorities as to .............
which traffic control signals should be installed first.
9.2.1 Engineering Data Requtred
A comprehensive investigation of traffic conditions and
physical characteristics, of the location is required to determine the
necessity for a signal installation and to furnish necessary data for the
proper design and operation of a signal that is found to be warranted. Such
data desirably should include:
The number of vehicles entering the intersection in each
hour from each approach during 16 consecutive hours of a
representative day. The 16 hours selected should
contain the greatest percentage of the 24-hour traffic.
Vehicular volumes for each traffic movement from each
approach, classified by vehicle type {heavy trucks,
passenger cars and light trucks, and public transit
vehicles), during each 1S-minute period of the two hours
in the morning and of the two hours in the afternoon
during which total traffic entering the intersection is
greatest.
Pedestrian volume counts on each crosswalk during the
same periods as the vehicular counts in paragraph (2)
above and also during hours of highest pedestrian
volume. Where young or elderly persons need special
consideration, the pedestrians may be classified bY
general observation and recorded by age groups as
fo 11 ow s:
a) under I3 years
b) 13 to 60 years
c) over 60 years
The 85-percentile speed of all vehicles
uncontrolled approaches to the location.
on the
A conditions diagram showing details of the physical
layout, including such features as intersectional
geometrics, channelization, grades, sight-distance
restrictions, bus stops and routings, parking
conditions, pavement markings, street lighting,
driveways, location of nearby railroad crossings,
distance to nearest signals, utility poles and fixtures,
and adjacent land use.
9-4
A collision diagram showing accident experience by type,
location, direction of movement, severity, time of day,
data, and day of week for at least one year.
The following data are also desirable for a more precise
understanding of the operation of the intersection and may be obtained
during the periods specified in (2) above:
Vehicle-seconds delay determined separately for each
approach.
The number and distribution of gaps in vehicular traffic
on the major street when minor-street traffic finds it
possible to use the intersection safely.
The 85-percentile speed of vehicles on controlled
approaches at a point near to the intersection but
unaffected by the control.
Pedestrian delay time for at least two 30-minute peak
pedestrian delay periods of an average weekday or like
periods of a Saturday or a Sunday.
9.2.2 Warrants
Warrants for Traffic Signal Installation. Traffic control
signals should not be installed unless one or more of the signal warrants in
the Manual are met. Information should be obtained by means of engineering
studies and compared with the requirements set forth in the warrants. If
these requirements are not met, a traffic signal should neither be put into
operation nor continued in operation (if already installed).
For the purpose of warranting signalization, a wide-median
intersection should be considered as one intersection.
When a traffic control signal is indicated as being
warranted, it is presumed that the signal and all related traffic control
devices and markings are installed according to the standards set forth in
the Manual. It is further presumed that signal indications are properly
phased, that roadways are properly designed, that adjacent traffic signals
are properly coordinated, that there is adequate supervision of the
operation and maintenance of the signal and all of its related devices, and
that the traffic signal controller will be selected on the basis of
engineering study and judgement.
9-5
An investigation of the need for traffic signal control
should include, where applicable, at least an analysis of the factors
contained in the following warrants:
Warrant 1-Minimum vehicular volume.
Warrant 2-Interruption of continuous traffic.
Warrant 3-Minimum pedestrian volume.
Warrant 4-School crossings.
Warrant 5-Progressive movement.
Warrant 6-Accident experience.
Warrant 7-Systems.
Warrant 8-Combination of warrants.
Warrant g-Four Hour Volumes.
Warrant lO-Peak Hour Delay.
Warrant 11-Peak Hour Volume.'
WArrant 12-Warrant Volumes for traffic-actuated signals.
(Departmental warrant curves)
9.2.3 Prioritizing
Prioritizing Warranted Signals. The decision as to which
warranted signal location is to be installed first should be based on a
priority ranking list. The priority ranking systems used in current
practice vary considerably, particularly in the assignment of weighted
values to the various ranking elements. Since it is not possible to
establish a prioritized rating system applicable to all agencies, each
agency utilizing such techniques should design their own priority ranking
system. Some commonly used priority considerations are listed in Table 9-1.
TABLE 9-1. ELEMENTS FOR CONSIDERATION IN SIGNAL PRIORITY RANKING SYSTEMS.
Satisf~qion of Volume Warrants Additional points for the number
of hours a warrant is met.
Satisfaction of Warrants Additional points for the number
Accidents
Coordination
· School Crossing Proximity
Pedestrian Volume
Intersection C, eometrics
Area Considerations
of warrants met.
Additional points for correctable
accidents over the warrant number.
Additional points if signal fits
into an arterial progression of
grid system. Reduction in points
if signal does not lend itself to
coordination.
Additional points if intersection
is a school crossing, or is
proximate to school crossing.
Additional points if signal location
has moderate to high pedestrian
activity associated with it.
Reduction in points for "T"
intersections. Additional points
for higher speed locations, sight
distance restrictions, vertical or
horizontal curvature conditions.
Points added or subtracted for
CBD, urban, or rural locations.
9-6
TI~FFIC S~N&LS ~continued~
* Will the placement of a signal cause an increase in
cut-thru traffic and/or speeds through a residen-
tial area?
* Will signal installation allow motorists on the
primary street to maintain a uniform pace without
increasing delay on the side street to 75% of the
cycle length or more?
* Is there a combination of the above conditions
which indicate that a signal will be an improvement
rather than a detriment?
To aid them in answering these questions, engineers compare
the existing conditions against nationally accepted minimum
guidelines. These guidelines (often called "Warrants") were
established from many observations at intersections throughout
the country by experienced traffic engineers. Where the guide-
lines were met, the signals generally were operating effectively
with good public compliance. Where the guidelines were not met,
public compliance was reduced, and additional hazards resulted.
If you would like any additional information on this subject,
please contact a City traffic engineer for additional resource
material.
TI~FFIC
The City of Arlington receives numerous requests for traffic
signal installations each year. If each of these requests were
granted nearly every intersection would be signalized and travel
on our arterial streets would be greatly impeded. A traffic sig-
nal that decreases accidents and improves the flow of traffic is
an asset to any community. On the other hand, an unjustified sig-
nal can be a source of danger and annoyance to all who use the
intersection. It is the role of the traffic engineer to weigh the
benefits and disadvantageous of traffic signal installation.
Both of these will be discussed.
A traffic signal should be judiciously employed as a means of
traffic control to provide both safe and efficient travel. A com-
mon fallacy is that traffic signals always prevent accidents.
Usually right angle collisions are reduced by traffic signals,
but the total number of collisions, especially the rear-end type,
increase. The City installs traffic signals at all arte-
rial/arterial and other major intersections. When a minor
street/major street signal is considered an increase in delay
always results for the side street motorists.
When can a traffic signal be an asset instead of a liability
to safety and efficiency? In order to answer this, traffic engi-
neers have developed a uniform means of evaluating a location for
a proposed traffic signal and they have to ask and answer a
series of questions:
* Are there so many cars on both streets that signal
controls are necessary to clear up the confusion or
relieve the congestion?
* Is the traffic on the main street so heavy that
drivers on the side street will try to cross when
it is unsafe?
* Are there so many pedestrians trying to cross a
busy main street that confusing, congested or
hazardous conditions result.?
* Are there so many school children trying to cross
the street at the same time that they need special
controls for their protection? If so, is a traffic
signal the best solution.?
* Does the collision history indicate that signal
controls will reduce the probability of collisions?
* Do two arterials intersect at this location and
will a signal help improve the flow of traffic?