Below is the uncorrected machine-read text of this chapter, intended to provide our own search engines and external engines with highly rich, chapter-representative searchable text of each book. Because it is UNCORRECTED material, please consider the following text as a useful but insufficient proxy for the authoritative book pages.
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.
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
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
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
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~.
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
