|
Trip Linking Procedures - Working Paper 3 - 1990 Bay Area Household Travel Survey
Click HERE for graphic. TABLE OF CONTENTS A. INTRODUCTION. . . . . . . . . . . . . . . . . . . . . . . . . 1 B. TRIP LINKING CONCEPTS . . . . . . . . . . . . . . . . . . . . 2 C. TRIP LINKING PROCEDURE. . . . . . . . . . . . . . . . . . . . 4 1. Indentification of Linkable Trips by Trip Purpose . . 4 2. Input and Output Variables. . . . . . . . . . . . . . 6 a. Input File Variables included in Output Linked Trip File. . . . . . . . . . . . . . . . . . . . . . . . 7 b. Computed variables for walk access/egress to all modes . . . . . . . . . . . . . . . . . . . . . . .12 c. Computed variables for non-walk access to transit. . . . . . . . . . . . . . . . . . . . .13 d. Computed variables for non-walk egress from transit. . . . . . . . . . . . . . . . . . . .15 e. Computed variables for transit passenger modes. . .16 f. Computed variables for passenger serving trip sequences . . . . . . . . . . . . . . . . . . . . .19 LIST OF TABLES AND FIGURES Table 1 Summary of Trip Purpose Linking . . . . . . . . . . .20 Table 2 Mode Priority Assignment for Linkable Trips . . . . .21 Table 3 Unlinked Input File Format . . . . . . . . . . . . .22 Table 4 Linked Output File Format. . . . . . . . . . . . . .23 Figure 1 Illustrative Examples of Reported Trips. . . . . . .26 -i- A. INTRODUCTION The 1990 MTC Travel Survey was conducted by E.H. White and Company, Nelson/Nygaard and Phase III Research of Northern California, to provide updated travel information to the 1965 Survey of the Bay Area Transportation Study Commission and the 1981 MTC Household Travel Survey. The survey consisted of a sample of 10,900 households in the nine county region. Interviewing was conducted by telephone between April 1st and October 31, 1990. Sample selection was by random digit dialing controlled to a predetermined county sample. In contrast to the 1965 and 1981 travel surveys, no households were surveyed as to their weekend travel patterns. Of the total sample of 10,900 households, 9,400 households were asked to report one-day travel diaries. The remaining 1,500 households provided multiple-weekday travel diaries. For all samples, detailed household, person and trip information was collected. Survey procedures are documented in 1990 Bay Area Travel Survey, E.H. White and Associates, January 1991. The Survey data was delivered to MTC on floppy diskettes in three basic files: the household, the person and the trip file. Minor changes were made to protect the confidentiality of the sample telephone number. A sample identification number replaces the telephone number in all three files. The methods outlined in this working paper use the trip file as input and may involve the other files marginally. The purpose of this paper is to report on the process for linking individually reported trip legs into trip segments suitable for travel demand analysis and travel model estimation. The next two sections of this working paper provides descriptions of trip linking concepts and the specific trip linking process. The Appendix gives a number of tables and input/output file formats. Two linked trip files are created in the trip linking process. The first linked trip file - the "standard" file - includes only the original 24 variables included in the input unlinked trip record file. The second linked trip file - the "extended" file includes the original 24 variables plus computed variables that will be useful in mode-of-access, mode-of-egress, and special travel behavior analyses. -1- B. TRIP LINKING CONCEPTS Linking of trips is a technical detail that arises out of the way trips are defined and reported in origin-destination travel surveys. It has been the practice in these surveys to report individual legs of a trip separately every time the traveller stops for a specific purpose on the way to an ultimate destination. The 1990 MTC telephone survey is no exception with its "walk", "change travel mode", and "serve passenger" trip segments. The basic reason for linking trips stems from the methods used for associating travel demand with demographic, economic and land use variables at origins and destinations of trips. The trips generated from home can be quantified if the characteristics of the households living in a zone are known. Similarly the trips attracted to a work place can be quantified if the employment characteristics at a zone of work are known. If trips are not linked, it is not possible to account for large numbers of trips ending in a transit terminal. This is due to the absence of economic activities in a transit terminal commensurate with the number of trips ending there. This does not mean that we are not interested in finding mode of access to, say, a BART station. Rather, it means that for travel demand model development, we need to link a change travel mode leg of a trip to its preceding/succeeding legs until we couple "legitimate" trip purposes from origins to destinations. The trip legs that need to be linked are those that have one of two trip purposes at either origin or destination: "change travel mode" and "serve passenger".1 These legs are considered intermediate legs in a trip sequence, and are combined (or linked) with other trips in the sequence. The linking is done in such a way that the ultimate purpose of the trip is not lost. The following examples show reported trips in the survey and how they are linked. ___________________________ 1) The 1981 MTC Travel Survey included change travel mode and serve passenger trip purposes. The 1990 Travel Survey further broke down the serve passenger trip purpose into three sub- categories: serve adult passenger, serve child passenger, and child care. See next footnote on the need to further split child care trips into child care (adult) versus child care (child) trips. -2- Example 1. A Palo Alto resident catches a ride with his wife to the CalTrain Station, rides the train to San Francisco and catches a Muni bus to work in the financial district. The trips are reported and linked as follows: Husband's Reported Trips Person No. Trip No. Purpose at Origin Mode Purpose at Destination A 1 Home auto passenger change mode A 2 change mode CalTrain psgr change mode A 3 change mode walk change mode A 4 change mode public bus change mode A 5 change mode walk Work Husband's Linked Trip Person No. Trip No. Purpose at Origin Mode Purpose at Destination A 1 Home CalTrain psgr Work It is clear that the reason for the five trip legs is to get from "home" to "work". Linking combines the characteristics of these trip legs into one linked trip. One major mode is selected for the linked home-to-work trip. In this case it will be CalTrain Passenger mode. Station access and egress modes are noted in the characteristics of the linked trip. Trip times are traced from origin to destination and the individual mode times are kept separately. Example 2. In example 1 above, the wife drives the car from home to the CalTrain station to drop off her husband. She then drives to drop off their child at school on her way to work. The sequence of trips is reported and linked as follows: Wife's Reported Trips Person No. Trip No. Purpose at Origin Mode Purpose at Destination B 1 Home auto driver serve passenger B 2 serve passenger auto driver serve child psgr B 3 serve child psgr auto driver change mode B 4 change mode walk Work Wife's Linked Trips Person No. Trip No. Purpose at Origin Mode Purpose at Destination B 1 Home auto driver Work -3- Child's Reported Trips Person No. Trip No. Purpose at Origin Mode Purpose at Destination C 1 Home auto passenger Education The child's trip (home-to-school) is left alone as reported. C. TRIP LINKING PROCEDURE 1. Identification of Linkable Trips by Trip Purpose A computer program should be written to link the reported trips. All trips made by one person in the household are examined as a unit. In the multi-day travel survey, all trips made by a person over the three to five day time period are treated as a unit. The reported trips are classified into three categories: unlinkable, potentially linkable, and linkable trips. Unlinkable are written out unaltered, except for possible format changes discussed later. Potentially linkable are examined further to determine whether linking will or will not take place. If linking is warranted, they become linkable. If not, they are treated as unlinkable. The first decision to be made is to identify a potentially-linkable sequence. To define such a sequence, a search is made for a first leg and continued until a sequence terminating condition occurs. A first leg is identified when the trip purpose at origin or destination is either child care2, serve child passenger, serve adult passenger, or change travel mode (codes 12, 13, 14, or 15, respectively). Subsequent trips are considered part of the sequence if they have codes 12, 13, 14, or 15 for trip purpose at origin and destination until a terminating condition occurs. ___________________________ 2) Child care - purpose=12 - was intended as a sub-purpose to serve child passenger. Children who were dropped off at day care or child care were also assigned the child care trip purpose code. This amounted to 21.2 percent (524 trips) of the 1,942 total child care trips encountered in the Travel Survey. Our intention is to treat child care trips by adults (16+) as a special class of serve child passenger trip, and to treat these child care (adult) trips as potentially linkable trips. This means that we should recompute the trip purpose for child care (child) trips as a new trip purpose, purpose=17. Trip purpose=17, child care (child) trips will be unlinkable trips. -4- Termination of a trip sequence occurs if: a. Standard trip purpose. The trip purpose at the destination is not 12, 13, 14 or 15; b. Last trip per person unit. The trip is the last one for the particular person under consideration. c. Out of region trips. The trip purpose at the destination is 12, 13, 14 or 15 but the succeeding leg ends outside the region, or the preceding leg comes from outside the region. d. Inconsistency of trip purposes in a sequence. The purpose at destination is not the same as the purpose at origin of the next trip. e. Time lapse. Transit sequences are terminated if the elapsed time between legs is one hour or more. Non-transit sequences are terminated if the elapsed time between legs is greater than 15 minutes. Table 1 gives the three way classification of trip sequences. Unlinkable trips (sequence types #1 through #4) are those that do not have codes 12, 13, 14, or 15 for trip purpose at either origin or destination. Therefore, the sequence consists of one leg only. They are read and written out unaltered. Potentially-linkable sequences (sequence types #5 through #9) which do not warrant linking are shown as the second category of trips. They include: a. one-leg sequences which have codes 12,13,14, or 15 at origin, destination or both. They may be trips ending in an airport to leave the region or trips starting at the airport to enter the region. They may also be change travel mode trips miscoded as serve passenger, or simply miscoded trips. b. A two-leg sequence which, if linked, would result in a home- to-home trip. They may include pleasure rides from home to ride transit and back home. They also include the typical home-to-serve passenger-to-home sequences. The third category comprises the linkable trip sequences (sequence type #10 through #21). As Table 1 shows, all trip sequences are linked to form one trip except for sequence types 20 and 21. These are linked to form two linked trips. Sequence type 21 is linked to form approximately two equal linked trips. For example, a three leg sequence is linked to form: linked trip 1 = leg 1 linked trip 2 = legs 2 + 3 -5- Similarly, a four leg sequence is linked to form: linked trip 1 = legs 1 + 2 linked trip 2 = legs 3 + 4 Sequence type 20 may represent a school carpool, a serve passenger trip to a transit terminal, a serve passenger trip to an airport, etc. For most of these trips we have to make the assumption that there are only two legs and that linking should divide the legs into two equal linked trips. The school carpool however requires an additional assumption. Assume there are two school carpool sequences of type 20 for the same person. If so, then check time trip started. If AM, link 1st leg, 2nd leg, 3rd leg, etc. and n-1 leg to form the first linked trip. "n" is the number of legs in the sequence. The second linked trip will be the last leg of the sequence. Hopefully this way the first linked trip will end at the school. For the PM sequence, the reverse is done, i.e., linked trip one is the first home-to-serve passenger leg. Linked trip two is the summation of the other legs. In effect, each one of sequence types 20 and 21 becomes two separate sequences. Later reference to first leg and last leg of a sequence should be applied properly to each of the two separate sequences in each of types 20 and 21. Also note that implementing terminating condition c above may best be done by separating (and not linking) those legs that leave the region immediately after identifying a potentially-linkable sequence. 2. Input and Output Variables Since linking involves combining several legs of a sequence, the variables for the linked trip come from the individual legs of a sequence. The input file format is in Table 3. The output (linked) file is similar to the input (unlinked) file except for change in definition of variables, and the addition of new variables resulting from linking. The output file format is in Table 4. The treatment of the variables affected by linking is described in the succeeding subsections. To avoid any confusion over terminology, two basic definitions are given here. -6- Trip legs are the unlinked trip records which are reported in the master survey trip file. In Table 1 all unlinkable trips and potentially-linkable are considered unlinked legs (or trips) in the input and output files. Trip sequences are sequential legs (or unlinked trips) which are combined into one linked trip except for two sequence-types in Table 1. Sequence-types 20 and 21 are combined into two linked trips each. For the first pass of the trip linking analysis, the master input trip file will be evaluated in terms of the 21 sequence type described in Table 1, and then written out onto 21 separate sub- files, before implementing trip linking procedures. Problemsome sequence types (#5, #6, #7, #8, #9, #12, #13, #14, #17, #18, #19, #20, and #21) will be manually reviewed for 'Coding errors. After making the necessary corrections to a copy of the master input trip file, the second pass of the trip linking analysis will implement the trip linking procedures. Separate subfiles will also be written out for persons who made no trips on their assigned travel day or who refused to participate in the travel diary portion of the travel survey. a. Input File Variables included in Output Linked Trip File We turn now to the details of each specific Variable in the output file. We follow the layout of the input file and indicate the changes made due to linking as the output variables are computed. The unlinked (input) trip file format is included in Table 3. The linked (output) trip file format for the "extended" trip file is included as Table 4. (1) - (4) variables in the input file (COUNTY, ID, TRAVDAY and PERSON) are not altered in the output file. The COUNTY code is the standard FIPS code. (5) Trip number (TRIPNO): The trip number output should be the trip number for the first leg of the sequence. This variable was originally coded as "1" for persons who did not travel on their assigned travel day ("NOTRIP" in columns 12-17), or who refused the travel diary ("REFUSE" in columns 12-17). The final unlinked trip files have been edited such that trip records for NOTRIP persons were written out with trip number = 0; trip records for REFUSED trip diary persons were written out with trip number = -1. This amounts to 951 REFUSED trip diary persons in the singleday sample and 737 trip diary persons in the multi-day sample. The no trip -7- persons amounted to 3,126 persons in the single-day sample and 1,983 persons in the multi-day sample. These NOTRIP and REFUSE records should also be written out on separate files for further analysis. (6) Census Tract at Trip Origin (OTRACT): This variable is taken from the first leg of the sequence. This field should be left blank for records containing the string "NOTRIP" or "REFUSE" for no trip persons or refused trip diary persons. (TRIPNO=O identifies the valid zero-trip persons. TRIPNO=-L will identify the invalid persons who refused the trip diary). (7) Census Block Group at Trip Origin (OBLKGRP): This variable is taken from the first leg of the sequence. Missing entries in this field are valid. (8) Census Tract at Trip Destination (DTRACT): This variable is taken from the last leg of the sequence. (9) Census Block Group at Trip Destination (DBLKGRP): This variable is taken from the last leg of the sequence. Missing entries in this field are valid. (10) Travel Mode (MODE): A linkable sequence of trips is expected to contain two or more legs with identical or different modes. One mode has to be selected for the linked trip from among the modes of the separate legs. Such a mode is thought of as predominant, major or more representative of the sequence. The problem of selecting mode of travel for sequences involving only "serve passenger" purposes does not arise. Since only drivers can serve passengers, mode of travel will be the same (driver) for all legs. However, there may be sequences where the drivers involved in serve passenger legs could ultimately change travel mode to ride transit. In this case, the modes will be different and a selection of a predominant mode is necessary. In the case of transit trips, where several "change travel mode" purposes may be involved, there will be a number of different modes for the separate legs. Walk, public bus and BART might be reported for the individual legs of a sequence. The predominant mode is selected by assigning a priority number to the reported modes of the legs and choosing the highest ranking mode for the linked trip. A -8- redetermined look up table is used to rank all possible modes as shown in Table 2. Highest priority for selection means lowest number. As shown in Table 2, the transit modes head the list of high-to-low priority. This indicates that where there is a transit leg in a sequence of linkable trips, that leg will be considered the predominant one and its mode will be used for the linked trip. The argument is that auto or walk access modes to a transit station are incidental to the main transit trip by bus or train. Also, where there are transit legs in a sequence, they tend to be longer and are more legitimately predominant. Some conflicts could arise between, say, an A.C. Transit District bus passenger transferring to Muni and ultimately to ferry on a recreation trip. In the present setup the ferry mode will be selected. Further analysis might be necessary to investigate such occurrences and could lead to a revision of the procedure. In the 1981 MTC travel survey, ranking of modes differed for San Francisco residents with streetcar (Muni Metro) preceding bus. For the rest of the region, bus preceded streetcar. Multi-modal streetcar / bus trips should be reported for analysis, though typically we can assume that a patron will spend a longer part of their journey on a streetcar than in a bus. (11) - (12) Trip Purpose at Origin (OPURP) and Trip Purpose at Destination (DPURP): The linking process discussed in section C.1 above and Table 1 specify the new trip purposes for the linked trip. (13) Time When-Trip Began (OTIME): This will be taken from the first leg of a sequence. The start times, as coded, are in standard military time (e.g., 1:30 PM is 1330 hours). The times as output on the linked trip file should be converted to decimal military time (e.g., 1:30 PM is 1350 hours) to facilitate straightforward trip duration analysis. (14)- Time when Trip Ended (DTIME): This will be taken from the last leg of the sequence. The trip finish times, as coded, are in standard military time (e.g., 1:30 PM is 1330 hours). The times as output on the linked trip file should be converted to decimal military time (e.g., 1:30 PM is 1350 hours) to facilitate straightforward trip duration analysis. (15) Number of Persons in Vehicle (VOCC): In the input file, this field contains the number of persons in vehicle for unlinkable non-transit trips, and linkable vehicle driver/passenger trips (codes -9- 1-7) to a transit terminal. Obviously the unlinkable trips are not altered. For linked transit trips with vehicle driver/passenger access, this variable should also be left blank. However, vehicle occupancy for mode of access/egress will be saved and stored as a separate variable. See later sections for proper treatment. For a linked trip involving two-or-more serve passenger legs, the Maximum number of persons in the vehicle (driver trips, modes=1, 3, 5) recorded should be entered in the output file for this variable. Checks should be made for multi-occupant motorcycle, moped and bicycle trips. By definition there should be no "serve passenger" legs with a mode "passenger". These trips will fall in the unlinkable category. If any are found they should be reported for further analysis. (16) Was This a Prearranged Vehicle Pool? (PREARR): For a linked trip with a predominant transit mode, this variable should be left blank. Note that entries for this variable in the input file for mode of access/egress legs to a predominant transit trip should be saved and used to construct a new variable as discussed later. For linked driver and passenger (mode codes=l - 7) trips with legs having "serve passenger" purposes, the value for PREARR is taken from the trip leg with the highest vehicle occupancy level (VOCC). (17) Resident Vehicle Used Identification Code (VEHICLE): For linked vehicle driver trips (mode codes=l, 3, or 5), this variable should be taken from the driver leg with the highest vehicle occupancy level (VOCC). For unlinked vehicle driver trips, this variable is written out unaltered. For linked transit trips, this variable should be left blank. For vehicle mode of access to/egress from transit, the entries should be saved and used for computing new variables as explained later. (18) Type of Parking Used (PARKTYPE): For linked vehicle trips that involve serve passenger legs, this variable is taken from the last driver mode (codes=l, 3, or 5) leg of the sequence. For unlinked vehicle driver trips, this variable is written out unaltered. For all other transit trips, it will remain blank per the predominant transit leg. Note that for those that have a driver mode of access to/egress from transit, the -10- entry from such legs is saved and a new variable created as explained later. (19 - 20) Amount Paid for Parking Cost (PARKCOST) & Time Unit for Parking Code (PARKUNIT): For linked vehicle trips involving serve passenger purposes, these.variables should be taken from the last leg of the sequence that has vehicle driver modes 1, 3, or 5. For unlinked vehicle driver trips, these variables are written out unaltered. For linked transit trips, these variables are blank. However, if a driver mode of access/egress is involved in the linked sequence, the entry for such a leg should be saved and new variables computed as explained later. (21) - (22) First Bridge Crossed (BRIDGE1) and Second Bridge Crossed (BRIDGE2): For driver and passenger predominant modes, a search is made for all legs of a sequence. If any leg has entries for these two variables, they should be transferred to this location in the output file. These will generally be serve passenger sequences. If more than one leg has entries, the entire sequence should be listed for further analysis. Only two bridges crossed should be included in the output file. For linked sequences with a predominant transit mode, this variable will be generally blank. If a leg is encountered with a bridge crossed, its entries for these two variables should be included in the output file. Entries will represent characteristics of the driver or passenger modes of access to/egress from transit. Such sequences should be listed for further analysis. (23) Transit Operator Code (TRANOPER): This is a new variable included in the 1990 Survey which will allow for analysis of multi-operator transit trips. This field was left blank if a non-bus operating transit operator (e.g., BART, CalTrain, AMTRAK) was used. For this output variable, the operator code should be taken from the first transit leg encountered in a trip sequence. If the first transit leg (transit boarding) encountered is mode 8, 10 - 16, 18 (transit modes) and the operator code is missing then this is probably a BART, CalTrain, AMTRAK, or private ferry leg. -11- New operator codes are assigned to these four operators, as follows: - BART (mode=14) - operator=31; - CalTrain (mode=15) - operator=32; - AMTRAK (mode=16) - operator=33; - Ferry (mode=18) - operator=34. Passengers on the Golden Gate Ferries are probably coded as mode=18 (ferry), operator=3 (Golden Gate Transit). Additional variables, described later, will document the second and third transit operators used in a linked trip sequence. Trip sequences with more than three transit operators involved in a trip should be reviewed manually. (24) How Transit Fare was Paid (FAREHOW)-This variable should be used from the first transit leg in a trip sequence (modes 8, 10 - 16, 18). Additional variables will be defined for the second, third, n-th transit leg involved in a transit trip sequence. (25) What Transit Fare was Paid (FAREPAID):This variable should be used from the first transit leg in a trip sequence (modes 8, 10 - 16, 18). Additional variables will be defined for the second, third, n-th transit leg involved in a transit trip sequence. b. Computed Variables for Walk Access/Egress to All Mode-s (26) Walk Access Time (in Minutes) at_Trip Origin (OWALK): a. For unlinked output trips, this variable will be blank. b. For linked trips, this variable is taken from the first leg of the sequence. If the first leg is not walk, then OWALK is left blank. If the first leg is a walk leg, then compute travel time from DTIME - OTIME (decimal military time). A reasonableness check should be made on the value obtained for walk at origin. Any linked trip with origin walk time over 30 minutes should be listed. Maximum, minimum and average walk times are to be reported for non-blank entries. (27) Walk Access Time (in minutes) at Trip Destination (DWALK): a. For unlinked output trips, this variable will be blank. -12- b. For linked trips, this variable is taken from the last leg of the sequence. If the last leg is not walk, leave blank. If the last leg is a walk leg, then compute travel time from DTIME - OTIME (decimal military time). A reasonableness check should be made on the value obtained for walk at trip sequence destination. Any linked trip with destination walk time over 30 minutes should be listed. Maximum, minimum and average walk times are to be reported for non-blank entries. (28) Transfer Walk Time (in minutes) (XFERWALK): a. For unlinked output trips this variable should be blank. b. For linked trips, the first and last legs of the sequence are ignored irrespective of their mode. A search should be made for intermediate walk legs and the XFERWALK is accumulated across these intermediate legs by summing their respective travel times (DTIME - OTIME). A reasonableness check should be made on the value obtained for transfer walk times. Any linked trip with transfer walk time over 30 minutes should be listed. Maximum, minimum and average walk times are to be reported for non-blank entries. c. Computed Variables for Non-Walk Access to Transit We now turn to identifying non-walk access-to-transit variables at the origin of a linked trip. Variables (29)-(41) that follow will be blank for all unlinked output trips and linked trips with a non- transit predominant mode (codes 1 - 7, 9, 17, 1924). For linked trips with a transit predominant mode (codes 8, 10 - 16, 18), a search is made through the sequence of unlinked trips to identify mode of access leg. Starting at the origin of the sequence, the legs are searched for modes 1 - 7, 9, 17, 19 - 22, and 24. The first leg with such a mode prior to the leg with the predominant mode is used to transfer information to the output file for variables (29)-(41), as indicated below. Usually the first leg in the transit trip sequence provides mode-of-access. The frequency of such occurrences should be reported, i.e., number of occurrences is reported where the first leg, second leg, third plus legs provide mode-of-access to transit. If no non-walk mode-of-access is encountered prior to the predominant leg, then variables (29) to (41) are left -13- blank. (29) Census tract of origin for non-walk access to transit (OACC): Use the variable OTRACT (6) for the selected access leg. (30) Census block group of origin for non-walk access to transit (OBGACC): Use the variable OBLKGRP (7) for the selected access leg. (31) Census tract of destination for non-walk access to transit (DACC): Use the variable DTRACT (8) for the selected access leg. (32) Census block group of destination for non-walk access to transit (DBGACC): Use the variable DBLKGRP (9) for the selected access leg. (33) Mode of travel for non-walk access to transit (MODEACC): Use the variable MODE (10) for the selected access leg. (34) Time when trip began for non-walk access to transit (OTACC): Use the variable OTIME (13) for the selected access leg. (35) Time when trip ended for non-walk access to transit (DTACC): Use the variable DTIME (14) for the selected access leg. (36) Number of persons in the vehicle for non-walk mode of access to transit (VOCCACC): Use the variable VOCC (15) for the selected access leg. (37) Was non-walk access to transit a Prearranged vehicle pool (PREARACC): Use the variable PREARR (16) for the selected access leg. (38) Resident vehicle number used for non-walk access to transit (VEHACC): Use the variable VEHICLE (17) for the selected access leg. (39) Type of parking for non-walk access to transit (PTYPEACC): Use the variable PARKTYPE (18) for the selected access leg. (40) Parking Cost for non-walk access to transit (PCOSTACC): Use the variable PARKCOST (19) for the selected access leg. -14- (41) Time unit for transit (PUNITACC): Use the variable' s leg. d. Computed Variables for Non-walk Egress from Transit The next group of variables represent characteristics of the non- walk mode-of-egress from transit for the destination end of a linked trip. A similar approach to that of the access characteristics is adopted here for egress characteristics. All unlinked trips and linked trips with a non-transit predominant mode will have blank entries for variables (42) - (54) that follow. For linked trips with a transit predominant mode (codes 8, 10 - 16, 18), a search is made through the sequence of unlinked trips to identify mode-of-egress leg. The sequence is searched backwards, starting with the destination of the linked trip, to identify the 1st leg with a mode of 1 - 7, 9, 17, 19 - 22, or 24 prior to reaching the predominant transit leg. Once the candidate leg is identified, the information for it is transferred to the output file. The specifics follow, but first a frequency of occurrence should be reported for the number of times the egress leg is the last in the sequence, the n-1 or n-2, etc. (42) Census tract of origin for non-walk egress from transit (OEGR): Use the variable OTRACT (6) for the selected egress leg. (43) Census block group of origin for non-walk egress from transit (OBGEGR): Use the variable OBLKGRP (7) for the selected egress leg. (44). Census tract of destination for non-walk egress from transit (DEGR): Use the variable DTRACT (8) for the selected egress leg. (45) Census block group of destination for non-walk egress from transit (DBGEGR): Use the variable DBLKGRP (9) for the selected egress leg. (46) Mode of travel for non-walk egress from transit (MODEEGR): Use the variable MODE (10) for the selected egress leg. -15- (47) Time when trip began for non-walk egress from transit (OTEGR): Use the variable OTIME (13) for the selected egress leg. (48) Time when trip ended for non-walk egress from transit (DTEGR): Use the variable DTIME (14) for the selected egress leg. (49) Number of persons in the vehicle for non-walk mode of egress from transit (VOCCEGR): Use the variable VOCC (15) for the selected egress leg. (50) Was non-walk egress from transit a prearranged vehicle pool (PREAREGR): Use the variable PREARR (16) for the selected egress leg. (51) Resident vehicle number used for non-walk egress from transit (VEHEGR): Use the variable VEHICLE (17) for the selected egress leg. (52) Type of parking for non-walk egress from transit (PTYPEEGR): Use the variable PARKTYPE (18) for the selected egress leg. (53) Parking Cost for non-walk egress from transit (PCOSTEGR): Use the variable PARKCOST (19) for the selected egress leg. (54) Time unit for parking cost for non-walk egress from transit (PUNITEGR): Use the variable PARKUNIT (20) for the selected egress leg. e. Computed Variables for Transit Passenger Modes Data collected in the 1990 Travel Survey will allow for the analysis of interoperator and intra-operator transfers; total boardings per linked person trip; and the extent of multi-operator linked trips. The computed variables described in this section pertain to the second, third, and n-th boarding within a transit trip sequence. The variables (55) through (66) are written out to the extended version of the linked trip file. -16- It is assumed that the maximum number of operators used in one transit sequence is three operators. It is also assumed that the maximum number of transit boardings in a transit sequence is five boardings. Unusual transit sequences of greater than three operators and/or five boardings should be listed and carefully reviewed before proceeding with the trip linking procedures. If need be, the assumption for three maximum operators and five maximum boardings will be adjusted. (55) Tally of Number of Transit Boardings in Trip Sequence (TOTBOARD): This variable is a simple tally of the number of transit boardings, i.e., transit passenger mode (MODE = 8, 10 - 16, 18) legs, within a transit trip sequence. This variable should be left blank for non- transit trip sequences. (56) Tally of Number of Transit Operators used in Trip Sequence (TOTOPER): This variable is a simple tally of the number of transit operators (TRANOPER) used within a transit trip sequence. Note that the TRANOPER variable was left blank for BART, CalTrain, AMTRAK, or private ferry boardings and is assigned for these operators (operator codes 31, 32, 33, and 34) during the trip linking procedure. Special cases, such as transit patron who boards a Muni bus, transfers to BART, then transfers to another Muni bus, should be characterized as a two operator transit trip sequence (TOTOPER=2). (57) Second Transit Operator used in the Trip Sequence (TRANOPR2): This is taken from the TRANOPER code from the second operator code encountered in a transit trip sequence. This field should be left blank for all nontransit trips and transit trips with only one transit operator involved. (58) Third Transit Operator Used in the Trip Sequence (TRANOPR3): This is taken from the TRANOPER code from the third operator code encountered in a transit trip sequence. This field should be left blank for all nontransit trips and transit trips with only one or two transit operators involved. (59) How Transit Fare was Paid in Second Transit leg (FAREHOW2): This variable is taken from the second transit leg in a trip sequence (modes 8, 10 16, 18) from the input variable FAREHOW. This field should be left blank for all non-transit trips and transit trips with only one transit boarding. -17- (60) How Transit Fare was Paid in Third Transit leg (FAREHOW3): This variable is taken from the third transit leg in a trip sequence (modes 8, 10 16, 18) from the input variable FAREHOW. This field should be left blank for all non-transit trips and transit trips with fewer than three transit boardings. (61) How Transit Fare was Paid in Fourth Transit leg (FAREHOW4): This variable is taken from the fourth transit leg in a trip sequence (modes 8, 10 16, 18) from the input variable FAREHOW. This field should be left blank for all non-transit trips and transit trips with fewer than four transit boardings. (62) How Transit Fare was Paid in Fifth Transit leg (FAREHOW5): This variable is taken from the fifth transit leg in a trip sequence (modes 8, 10 16, 18) from the input variable FAREHOW. This field should be left blank for all non-transit trips and transit trips with fewer than five transit boardings. (63) What Transit Fare was Paid in Second Transit Leg (FAREPD2): This variable is taken from the second transit leg in a trip sequence (modes 8, 10 16, 18) from the input variable FAREPAID. This field should be left blank for all non-transit trips and transit trips with fewer than two transit boardings. (64) What Transit Fare was Paid in Third Transit Leg (FAREPD3): This variable is taken from the third transit leg in a trip sequence (modes 8, 10 16, 18) from the input variable FAREPAID. This field should be left blank for all non-transit trips and transit trips with fewer than three transit boardings. (65) What Transit Fare was Paid in Fourth Transit Lee (FAREPD4): This variable is taken from the fourth transit leg in a trip sequence (modes 8, 10 16, 18) from the input variable FAREPAID. This field should be left blank for all non-transit trips and transit trips with fewer than four transit boardings. (66) What Transit Fare was Paid in Fifth Transit Leg (FAREPD5), This variable is taken from the fifth transit leg in a trip sequence (modes 8, 10 16, 18) from the input variable FAREPAID. This field should be left blank for all non-transit trips and transit trips with fewer than five transit boardings. -18- f. Computed Variables for Passenger Serving Trip Sequences The computed variables described in this section pertain to the serve passenger activities associated with a trip sequence. The variables are simple tallies of the count of serve passenger stops encountered in a linked trip sequence. These intermediate serve passenger stops (i.e., dropping off / picking up kids at school or child care; dropping off or picking up spouse on their way to work; dropping off or picking up carpool partners) may be helpful in understanding the choice of travel modes as it relates to family / household travel behavior. The variables (67) through (69) are written out to the extended version of the linked trip file. (67) Tally of Number of Child Care St@s in Linked Trip Sequence (STOPCCA): This variable is a simple tally of the number of child care (adult) trip stops within a trip sequence (DPURP = 12). As re-defined in the trip linking procedures, purpose=12 trips are only made by persons 16 years-and-older; purpose=17 trips are child care trips made by the child, we assume to attend child care or day care. The default for this variable is blank. If this is not a linked trip (i.e., only one trip leg in the trip sequence) then this variable should also be left blank. (68) Tally of Number of Serve Child Passenger Stops in Linked Tri]p Sequence: This variable is a simple tally of the number of serve child passenger trip stops within a trip sequence (DPURP = 13). The default for this variable is blank. If this is not a linked trip (i.e., only one trip leg in the trip sequence) then this variable should also be left blank. (69) Tally of Number of Serve Adult Passenger Stops in Linked Trip Sequence (STOPSAP): This variable is a simple tally of the number of serve adult passenger trip stops within a trip sequence (DPURP = 14). The default for this variable is blank. If this is not a linked trip (i.e., only one trip leg in the trip sequence) then this variable should also be left blank. -19- Click HERE for graphic. -20- Table 2 Mode Priority Assignment for Linkable Trips Priority, in 1990 MTC Travel Survey Mode of Travel Descending Order Code Description 1 14 BART Passenger 2 15 CalTrain Passenger 3 18 Ferry Passenger 4 11 Streetcar Passenger 5 8 Public Bus Passenger 6 10 Cable Car Passenger 7 12 Shuttle Bus Passenger 8 13 Dial-a-Ride Passenger 9 9 School Bus Passenger 10 7 Taxi, Limo Passenger 11 4 Truck Passenger 12 6 Van Passenger 13 2 Auto Passenger 14 3 Truck Driver 15 5 Van Driver 16 1 Auto Driver 17 20 Motorcycle passenger 18 19 Motorcycle driver 19 21 Moped 20 22 Bicycle 21 23 Walk 22 24 Other 23 16 AMTRAK Passenger 24 17 Airplane Passenger * For non-San Francisco resident bus and streetcar trips, the modes bus and streetcar were reversed. -21- Table 3 Unlinked Trip Record File Format - 1990 Travel Survey Variable Record Variable Variable Number Position Name Description Format 1 1 - 2 COUNTY County of Residence, FIPS code I2 2 3 - 7 ID Household Identification Number I5 3 8 TRAVDAY Travel day (1=Monday,...5=Friday) I1 4 9 PERSON Person Identification Letter A1 5 10 -11 TRIPNO Trip number I2 6 12-17 OTRACT Census tract at trip origin I6 6 12-17 Alternate: "NOTRIP " (no trips made) A6 6 12-17 "REFUSE" (refused diary) A6 7 18 OBLKGRP Block group at trip origin I1 8 19 - 24 DTRACT Census tract at trip destination I6 9 25 DBLKGRP Block group at trip destination I1 10 26 - 27 MODE Travel mode code I2 11 28 - 29 OPURP Purpose at trip origin code I2 12 30 - 31 DPURP Purpose at trip destination code I2 13 32 - 25 OTIME Military time at trip start I4 14 36 - 39 DTIME Military time at trip end I4 15 40 VOCC Persons in vehicle I1 16 41 PREARR Prearranged vehicle pool I1 17 42 VEHICLE Vehicle used identification code I1 18 43 PARKTYPE Type of parking used code I1 19 44 - 47 PARKCOST Amount paid for parking I4 20 48 PARKUNIT Time unit for parking code I1 21 49 - 50 BRIDGE1 First bridge crossed code I2 22 51 - 52 BRIDGE2 Second bridge crossed code I2 23 53 - 54 TRANOPER Bus operator code I2 24 55 FAREHOW How fare was paid code I1 25a 56-59 FAREPAID if FAREHOW=1, then fare amount I4 25b 56-58 FAREPAID if FAREHOW=2, then pass code I3 25c 56 FAREPAID if FAREHOW=3, then 1=free, 2=paid I1 25d 56-59 FAREPAID if FAREHOW=4 or 5, then blank I4 Single Day Sample IDs = I - 9439 81,451 records Multi Day Sample IDs = 10001 - 11486 43,291 records -22- Table 4 Linked Trip Record File Format - 1990 Travel Survey Variable Record Variable Variable Number Position Name Description Format 1 1 - 2 COUNTY County of Residence, FIPS code I2 2 3 - 7 ID Household Identification Number I5 3 8 TRAVDAY Travel day (1=Monday,...5=Friday) I1 4 9 PERSON Person Identification Letter Al 5 10 -11 TRIPNO Trip number I2 6 12-17 OTRACT Census tract at trip origin I6 6 12-17 Alternate: "NOTRIP " (no trips made) A6 6 12-17 "REFUSE" (refused diary) A6 7 18 OBLKGRP Block group at trip origin I1 8 19 - 24 DTRACT Census tract at trip destination I6 9 25 DBLKGRP Block group at trip destination I1 10 26 - 27 MODE Travel mode code I2 11 28 - 29 OPURP Purpose at trip origin code I2 12 30 - 31 DPURP Purpose at trip destination code I2 13 32 - 25 OTIME Military time at trip start I4 14 36 - 39 DTIME Military time at trip end I4 15 40 VOCC Persons in vehicle I1 16 41 PREARR Prearranged vehicle pool I1 17 42 VEHICLE Vehicle used identification code I1 18 43 PARKTYPE Type of parking used code I1 19 44 - 47 PARKCOST Amount paid for parking I4 20 48 PARKUNIT Time unit for parking code I1 21 49 - 50 BRIDGE1 First bridge crossed code I2 22 51 - 52 BRIDGE2 Second bridge crossed code I2 23 53 - 54 TRANOPER Bus operator code I2 24 55 FAREHOW How fare was paid code I1 25a 56-59 FAREPAID if FAREHOW=1, then fare amount I4 25b 56-58 FAREPAID if FAREHOW=2, then pass code I3 25c 56 FAREPAID if FAREHOW=3, then 1=free, 2=paid I1 25d 56-59 FAREPAID if FAREHOW=4 or 5, then blank I4 Computed Variables for Walk Access/Egress - All Modes 26 60-61 OWALK Walk Access Time, Trip Origin I2 27 62-63 DWALK Walk Access Time, Trip Destin.I2 28 64-65 XFERWALK Walk Transfer Time I2 -23- Table 4 (continued) Linked Trip Record File Format - 1990 Travel Survey Variable Record Variable Variable Number Position Name Description Format Computed Variables for Non-Walk Access to Transit 29 66-71 OACC Origin Census Tract of Access I6 30 72 OBGACC Origin Block Group of Access I1 31 73-78 DACC Dest. Census Tract of Access I6 32 79 DBGACC Dest. Block Group of Access I1 33 80-81 MODEACC Travel Mode of Non-Walk Access I2 34 82-85 OTACC Trip Start, Access to Transit Trip I4 35 86-89 DTACC Trip End, Access to Transit Trip I4 36 90 VOCCACC Vehicle Occupancy, Access Trip I2 37 91 PREARACC Prearranged Carpool, Access Trip I1 38 92 VEHACC Vehicle Used, Access to Transit Trip I1 39 93 PTYPEACC Parking Type, Access to Transit Trip I1 40 94-97 PCOSTACC Parking Cost, Access to Transit Trip I4 41 98 PUNITACC Parking Unit, Access to Transit Trip I1 Computed Variables for Non-Walk Egress from Transit 42 99-105 OEGR Origin Census Tract of Egress I6 43 106 OBGEGR Origin Block Group of Egress I1 44 107-112 DEGR Dest. Census Tract of Egress I6 45 113 DBGEGR Dest. Block Group of Egress I1 46 114-115 MODEEGR Travel Mode of Non-Walk Egress I2 47 116-119 OTEGR Trip Start, Egress from Transit Trip I4 48 120-123 DTEGR Trip End, Egress from Transit Trip I4 49 124 VOCCEGR Vehicle Occupancy, Egress Trip I2 50 125 PREAREGR Prearranged Carpool, Egress Trip I1 51 126 VEHEGR Vehicle Used, Egress to Transit Trip I1 52 127 PTYPEEGR Parking Type, Egress to Transit Trip I1 53 128-131 PCOSTEGR Parking Cost, Egress to Transit Trip I4 54 132 PUNITEGR Parking Unit, Egress to Transit Trip I1 Computed Variables for Transit Passenger Modes 55 133 TOTBOARD Tally of Total Transit Boardings I1 56 134 TOTOPER Tally of Operators used in SequenceI1 57 135-136 TRANOPR2 Second Transit Operator Boarded I2 58 137-138 TRANOPR3 Third Transit Operator Boarded I2 59 139 FAREHOW2 Second Transit Leg, How Fare Paid I1 60 140 FAREHOW3 Third Transit Leg, How Fare Paid I1 61 141 FAREHOW4 Fourth Transit Leg, How Fare Paid I1 62 142 FAREHOW5 Fifth Transit Leg, How Fare Paid I1 -24- Table 4 (continued) Linked Trip Record File Format - 1990 Travel Survey Variable Record Variable Variable Number Position Name Description Format Computed Variables for Transit Passenger Modes (continued) 63 143-146 FAREPD2 Second Transit Leg, Fare Paid I4 64 147-150 FAREPD3 Third Transit Leg, Fare Paid I4 65 151-154 FAREPD4 Fourth Transit Leg, Fare Paid I4 66 155-158 FAREPD5 Fifth Transit Leg, Fare Paid I4 Computed Variables for Passenger Serving Trip Purposes 67 159 STOPCCA Tally of Child Care Stops I1 68 160 STOPSCP Tally of Serve Child Stops I1 69 161 STOPSAP Tally of Serve Adult Stops I1 -25- Click HERE for graphic. -26- Click HERE for graphic. -27- Click HERE for graphic. -28- Click HERE for graphic. -29-
