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OCR for page 25
25
Chapter Four
FIELD DATA COLLECTION
One of We major objectives of this stuffer was to assemble
a comprehensive data base of traffic operations at stop-
controDed intersections. A major investment of resources
was made to collect data at a wade variety of intersections.
This chapter describes Me data that were collected.
SAMPLING PLAN
Flow and geometric considerations were established as
the basis for He sampling plan used to guide the selection
of candidate sites. Since capacity measurements were
highly desirable, the first criterion was that continuous
queueing Ewing on at least one stop-con~olled approach
for at least five minutes on a normal day. Next, regions
in each of five geographic areas of Be United States were
identified: San Francisco/San lose, California
metropolis area (southwest sector), Montgomery and
Auburn, Alabama (southeast sectors, Troy and
Rochester, New York (northeast sector), Milwaukee,
Wisconsin (central sector), and Portland, Oregon
(northwest sector). A guideline of fourteen TWSC and
six AWSC ~ntersecdon sites in each geographic sector
was established.
Within each geographic sector, guidelines were
established for numbers of sites for Free different
geometric configurations. These are shown in Table 22.
OCR for page 26
Configuration #2
Geometry
.
Lanes on major street = 2
Ides on minor street = 1
Optional major street exch~sive left~n lane
Number of Sites
· Urban areas = 2
· Rural areas = 0
· Total sites = 2
Configuration YE
Geometry
T sues on major street = 1
· T. ones on minor street = 1
· Optional major street e~cch~sive lemon lane
Number of Sues
· Urban area = 3
· Rural area = 0
· Total sites = 3
26
Table 22. AWSC ~tersechon Sampling Plan Configurations
~1
tl
Configuration #3
Geometry
. ~ fines on major street = 2
· I ages on minor street = 2
· Optional major strew exclusive left-turn lane
Number of Sites
· Udoan areas = 1
· Rural areas = 0
· Total sites = 1
-
F1~1
OCR for page 27
2
Total
6
27
GEOMETRIC CONlilGURATIONS
A total of 30 unique AWSC intersection sites were
videotaped during 41 different time penods. In most
cases, fom video cameras were used at each site producing
a total of over 150 individual videotapes. Overall, the
sample size objective of 30 AWSC intersection was met.
Table 23. Number of Unique AWSC Intersection Sites
Tables 23 and 24 show the number of sites Hat were
videotaped by sector and by geometric configuration for
AWSC intersections. The sampling plan retirements
are also shown. In most cases, Be requirements were
either met or exceeded.
....... . ................................... ... ....................................................................................
.............. ~. :: : ::
·............................................................
::::::::::::::::::::::::::::::::::::. ::::::::::::::::::::::.. :: ::: O' - Cole:::: ::: ::::::: *:::::.-.- :.::: :. :: :: ::::::
. ~. . ~...........................
. ,,., .. . . ,.,.
Total _
_
7 2 3
0 2 0
1 1 1
8 5 4
20
30
15
10
5
30
Table 24. Number of Videotaping Periods-AWSC Intersection Sites
...................................................... ;
. . . ............ ..... ..
...... c ~
2 : F ............................. ...... ,., . c c .~.
............ '" " """' ' ' ' '"' :' '' ~ :'' ' . ~. ~ . e,
1 8 2 6 6 5
2 0 2 0 0 3
3 2 2 2 2 1
10 6 8 8 9
27
15 .
10 .
5 .
30
GEOMETRY GROUPS
... ..
The field sites are classified into six groups, according to
the number of lanes on the intersection approaches. The
Table 25. Classification of Field Sites by Geometry
n~berofindividual approaches and intersections in each
group are listed in Table 25.
2
3
4
5
6
2
2
2
1,2
3
1
1
2
2
1,2
3
4S
4
8
28
a
12
4
4
6
10
2
Notes: SubjectApproach is the approach under shady. Opposing Approach is the approach opposite to the subject approach Conflicting Approaches are the two
approaches to the leR and rift ofthe subject approach
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28
Group ~ Sites
Twelve AWSC intersections had single lanes on each
approach. Data were available for 45 approaches. Table
26 lists the sites with single lanes on all approaches.
Table 26. Single Lane Sites
....... ' : '"' . _
...................................... ; _
....................................... ......................... .......................... ......................
, ~ , . sU~ . ~. If.
. . . .... ... ..~. hi-. - ~
...... ; ................................... ................................ . ~'' .~
SWA006 ~1 1
SWAOl l 1 1 1
NEA201 1 1 1
NEA204 1 1 1
NEA205 1 1 1
NEA.206 1 1 1
NEA208 1 1 1
CEA303 1 1 1
CEA304 1 1 1
NWA401 1 1 1
NWA403 i 1 1
NWA40S 1 1
-
Table 27. Single Lane Approaches on Multi-Lane Sites (Groups 2, 3,
and 4)
::::::::::::::::::::::::::::::::::::::::::::::::::::::::::: .~. .~
8~ I~ZI
Group 2
NWA407 NB 1 1 2
SEA101 WB 1 1 2
NWA407 SB 1 1 1
NEA207 SB 1 1 1
SWA004 SB 1 1 ~2
Group 3a
SWAOOgSB 1 2 O
SWA002SB 1 2 O
Group 3b .
SEA1OSEB 1 2 O
SWA009NB 1 2 2
.
Group 4a
NWA407WB 1 2 1
SWA004EB 1 2 1
NEA207WB 1 2 1
l
Group 4b
NWA402SB 1 2 1
NWA406WB 1 3 1
NWA402WB 1 2 2
N1NA406NB 1 2 3
SEA106EB 1 2 2
2
2
2
1
. . .
1
2
o
2
l
2
Groups 2, 3, and 4 Sites
Seventeen approaches at 14 AWSC intersections had one
lane on the subject approach and at least two lanes on one
of the other approaches Table 27 lists the single lane
approaches Mat have some combination of single and
multiple lanes once opposing and conflicting approaches.
Groups 5 and 6 Sites
Twenty-eight approaches at nine AWSC intersections had
twolanes once subject approach end combinations of 1,
2, or 3 lanes one approaches. Tables 2S, lists these
Group 5 sites. Two sites had three lanes on each
approach. Table 29 lists these Group 6 sites.
Table 28. Group 5 Sites
NEA202
NEA203
SEA104
SEA107
CEA307
CEA308
2
2
2
2
2
2
2
2
2
2
2
2
NWA402
NWA406
SEA101
2
2
2
2
~_ .
Table 29. Group 6 Sites
SWA007
SWA010
................................. ;.
. 't.t-- - - - -. ~ ~ -~ :
: :-:::::: :-::::: ::: :::::::::::: ; ! .' .! ' ! ! ' '! !-' ' ! ': ' : ! .' ' . ':' ' ' ' '-' '-'-' ,.,.,.,.,.,.,., :.,.,., , , ,.,.,.,., I ., . ,., ~.' : ;
.................. - - - ... -.
... - -.: : '., ,:.2- - ........................................... ' ' '' -' ' ::- ':
::::::::::::::::::::::::::: :::-::::::: :-:-: :-:-:-: :-:::::::: :::::: :-:-:-:-:-:-:. - - - . . .:::::::::: :::.-:::::::: ::::::::::-:::::-:-: :-:-:-:-:- -:-:-: ~ :::::::
SWA007 3 3 3 3
. SWAO10 3 3 3 3
3
DATA REDUCTION
3
F'our video cameras were used to record traffic
operations at each of the 41 AWSC ~ntersechons studied.
Data were reduced from We videotapes using the Traffic
Data Input Program (Boesen, et.al., 1991~. The time
Cat We vehicle passed through tile center of We
intersection, vehicle type, and directional movement were
recorded for each vehicle passing through We
intersection. For all vehicles on a stop-controlled
approach, the times for Tree over evens were also
OCR for page 29
29
recorded: entry into Me queue, arrival at We stop line,
and departure from the stop fine. Blockage events (such
as by pedestrians or bicycles) were also recorded.
The data types produced for each site are listed ~ Table
30.
Table 30. Data Types Produced for Each Site
Intersection Geometry Data
·Number of lanes per approach
·Lane designations
·Grades
Traffic Flow Data
·Traffic flow rates for all movements
·Tmffic stream composition for all movements
·Capacity flow rate
Gap and Headway Data
· Service times for various opposing/conflicting flow combinations
.
Raw Data Required for Model Esffmaffon
For Each Vehicle
·Event time at conflict point
·Movement direction
·Vehicle type
·Lane used
· Event time at end of queue
· Event time at ilont of queue
·Event time departing queue
Computed or DeH`red Data R4u~ for Model E~bnadon l
For Each Traffic Stream
·Flow rates
·Stream composition
For Each Vehicle
· Service time for each opposing/conflicting case
· Meshed or estimated capacity
· Service time or delay
·Queue delay
·Totaldelay
TRAGIC CHARACTERISTICS
The data sets Hat were used for analysis of service time,
cap acid, and debar characteristics included IS20 5-m~nute
data points. Of these, 844 data points were from Group ~
sites, 168 from Groups 2, 3, and 4 sites, and 808 from
Group 5 sites. This accounts for a total of 15 1.67 hours of
intersection operations.
Tables 31 through 34 show the mean, minimum, and
maximum values for flow rate, total delay, senice time,
and percent time queued for this data set. Figures 5
Trough ~ show a frequency distribution for flow rate, total
delay, service time, and percent time queued for all data.
The numbers shown on the x axis of the figures are the
upper bound of the frequency range. Some of the major
characteristics of the data set include:
.
.
.
54 percent of the flow rate date range from 12 vph
to 200 vph, 15 percent of the data points are
above 600 vph.
77 percent of the total delay data are less than 10
sec/veh, 7 percent of the data are above 30
sec/veh.
42 percent of He service time data are between 2
and 4 seconds; 45 percent of the data are between
4 and 6 seconds.
21 percent of He percent time queued data are
less than 10 percent; 21 percent are between 10
and 20 percent; 29% of the data points are above
50 percent time queued.
Table 31. Flow Rate Data
. ~; 1 '''~'''''1"''~""' 1
Mean 200 262 227 222
Minimum 12 12 12 12
Maximum 912 900 864 912
Note Gl are the Group 1 sites G234 are the Groups 2 to 4 sites G5 are
the Group S sites
Table 32. Total Delay Data
..... I . ....... ... ................. ........ , , ., I. .~
·:: :~:-:-:-:-:-:-:-:-:-:~:-: . :-:-:-:-:-:-:-:-:-: ·:-:-:-: :-:-:-:-:-:-:-:-:-.~:-:-:-:~:~: ' 'a !_ -!~ ! ' ~ :::::::: : ~ :-:-::-: ::: :-:-:-:-:-:: ::-::
Mean 76 103 13 1 101
Minimum 19 14 15 14
~ Maximum 41 8 53 0 129 5 129 5
Note Gl are the Group 1 sites G234 are the Groups 2 to 4 sites G5 He
Tic Group S sites
Table 33. Percent Time Queued Data
.. ; ; £3 4 - 5
..................................... ........................ ....................... , . ........ ; ....... ;
Mean 29;0 36 8 33 4 315
Minimum 0 0 9 O O
Maximum 100 0 98 5 100 0 100 0 l
Note Gl are the Group 1 sites G234 are Me Groups 2 to 4 sites G5 are
Me Group S 8~.
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30
Table 34. Service Time Data
Mean 4.4 4.4 4.4 4.4
Minimum 1.4 1.2 1.4 1.2
Maximum 16.4 9.5 13.9 16.4
Note: G1 are Me Group 1 sew G234 arc the Groups 2 to 4 sites. G5 are
the Group s sites.
1 000
800
~ 600
,
or
400
200
O
AWSC Intersection Data Sururnary
Flow Rate Dala
200 400 600 800 1000
Flow Rate Range
Figure 5. Flow Rate Data
1400 -
1 200 -
:,1000 -
.,, 800-
600-
400
200 -
n
AWSC Intersection Data Summary
Total Delay Dam
_ 10 20 30 40 50 60 70 80 90 100
Total Delay Range
Figure 6. Total Delay Data
800
600
400
200
o
AWSC Intersection Data Surrey
Service Time Data
4 6 8 10 12 14 16 18 20
Service Time Range
E9gu" 7. Service Time Data
AWSC Intersection Data Summary
Percent Time Queued Data
350
300
:~250
' 200
[150
100
50
O r`~ I rem' I ~
10 20 30 40 50 60 70 80 90
Percent Time Queued Range
Figure 8. Percent Time Queued Data
Representative terms from entire chapter:
time queued
