Plausibilization of survey data

By comparing each survey record with the timetable information of the Visum network model it is possible to identify and correct survey records which state an incorrect path. Incorrect lines or line routes or time profiles are replaced by correct lines or line routes or time profiles. Furthermore, additional data is added to each data record, such as times of departure and of arrival, travel time and trip distance, used lines and walk links.

Note: The boarding and alighting stops stated in the interview data records must exist in the analyzed network. If this is not the case, the record in question is ignored. If one of these stops is deleted after reading survey data from file, all paths from/to these stops will get lost.

Plausibilization: Basic approach

As a rule, the plausibilization includes the following steps.

1.  Validity check of the survey path leg (Image 284)

2.  Validity check of the pre-survey leg (Image 285)

3.  Validity check of post-survey leg

For each of these steps, the validity check can be run several times, in order to check the survey data successively with hard-to-meet criteria, which become easier and easier with each run.

Note: In single-row survey data records, the pre-survey leg as well as the post-survey leg may consist of one or two path legs each (User Manual: Format of a single-row survey file).

  • Inner path leg leading from PreStop to BoardStop and from AlightStop to SucStop respectively.
  • Outer path leg leading from OrigStop to PreStop and from SucStop to DestStop, respectively.

In multi-row survey data records, the previous section as well as the post-survey leg may consist of any number of path legs (User Manual: Format of a multi-row survey file).

Validity check of the survey path leg

Image 284: Validity check of the survey path leg

* In case of multiple vehicle journeys, the one with the minimum sum of run time and wait time is chosen.

Validity check of the pre-survey leg (Example with 1 or 2 pre-survey path legs)

Image 285: Validity check of the pre-survey leg

* In case of multiple vehicle journeys, the one with the minimum sum of run time and wait time is chosen.

Validity check of post-survey leg

The validity check of the post-survey path leg(s) is performed accordingly (Image 285).

Status IDs for the plausibilization quality

In a result file and also in lists (PuT paths and PuT path legs), a status ID (range 0...10) describes the quality determined by validity check and plausibilization for each survey record:

Table 297: Status indicators for the surveyed path leg

Status indicators for the surveyed path leg (E)

0

Not yet checked

Plausible

Plausible: Corresponds to the specifications (1)

A vehicle journey could be found in the surveyed time profile (or surveyed line route or line, depends on preciseness of input data), which connects boarding stop and alighting stop of the surveyed path leg and starts within the time tolerance interval defined for the time of departure from the boarding stop.

Plausible: Deviating line route or time profile (2)

A vehicle journey could be found in another time profile (or line route) of the surveyed line, which connects boarding stop and alighting stop of the surveyed path leg and starts within the time tolerance interval defined for the time of departure from the boarding stop.

Plausible: Deviating line (3)

A vehicle journey could be found in a time profile (or line route) of another line, which connects boarding stop and alighting stop of the surveyed path leg and starts within the time tolerance interval defined for the time of departure from the boarding stop.

Plausible: One path leg requires an additional transfer (5)

For the surveyed path leg, an indirect connection could be found by timetable-based search (shortest path search) which departs from the boarding stop within the tolerance interval defined for the departure time from this stop and includes at least one transfer (and walk links, if applicable).

Not plausible

Unplausible: No direct line route found (7)

Implausible, because none of the line routes (which are valid due to current parameter settings) connects boarding stop and alighting stop and connection search is not permitted either.

Unplausible: No departure at specified time (8)

Implausible, because the time profiles of the line routes (which are valid due to current parameter settings) connecting boarding and alighting stop do not include a departure within the time tolerance interval defined for the time of departure from the boarding stop and connection search is not permitted either.

Unplausible: No connection found (9)

Implausible, because no connection from boarding to alighting stop starting in the given time frame could be found during connection search calculation.

Table 298: Status indicators for the pre-survey leg

Status indicators for the pre-survey leg (V)

Untreated (0)

Does not exist

Plausible

Plausible: Corresponds to the specifications (1)

A vehicle journey could be found in the pre-survey leg time profile (or pre-survey leg line route or line, depends on preciseness of input data), which meets the condition defined for the permitted time span.

Plausible: Deviating line route or time profile (2)

A vehicle journey could be found in another time profile (or line route) of the preceding line, which meets the condition defined for the permitted time span.

Plausible: Deviating line (3)

A vehicle journey could be found in a time profile (or line route) of another line, which meets the condition defined for the permitted time span.

Plausible: Unplausible pre-survey leg or post-survey leg replaced by direct connection (4)

A direct vehicle journey from OriginStop to BoardStop with a shorter journey time (Factor • Journey time of Direct connection + constant < Journey time of pre-survey leg) compared to the plausible (multi-part) pre-survey leg could be found and is used instead.

Plausible: One path leg requires an additional transfer (5)

Replacing at least one of the pre-survey path legs by an indirect connection which was found by timetable-based connection search (incl. transfer(s) and walk link(s), if applicable).

Plausible: Unplausible pre-survey leg or post-survey leg replaced by shortest path (6)

Replacing the implausible (multi-part) pre-survey leg from OriginStop to BoardStop by a connection with an arrival time matching the departure time of the survey line from the BoardStop.

Not plausible

9

Implausible, because no path leg (or sequence of path legs) could be found meeting the given validity check criteria.

Status indicators for the post-survey leg (N)

Untreated (0)

Does not exist

Plausible

Plausible: Corresponds to the specifications (1)

A vehicle journey could be found in the post-survey leg time profile (or post-survey leg line route or line, depends on preciseness of input data), which meets the defined for the permitted time span.

Plausible: Deviating line route or time profile (2)

A vehicle journey could be found in another time profile (or line route) of the post-survey leg line, which meets the condition defined for the permitted time span.

Plausible: Deviating line (3)

A vehicle journey could be found in a time profile (or line route) of another line, which meets the condition defined for the permitted time span.

Plausible: Unplausible pre-survey leg or post-survey leg replaced by direct connection (4)

A direct vehicle journey from AlightStop to DestStop with a shorter journey time (Factor • Journey time of Direct connection + constant < Journey time of post-survey leg) compared to the plausible (multi-part) post-survey leg could be found and is used instead.

Plausible: One path leg requires an additional transfer (5)

Replacing at least one of the post-survey path legs by an indirect connection which was found by timetable-based connection search (incl. transfer(s) and walk link(s), if applicable).

Plausible: Unplausible pre-survey leg or post-survey leg replaced by shortest path (6)

Replacing the implausible (multi-part) post-survey leg from AlightStop to DestStop by a connection with a departure time matching the arrival time of the survey line at the AlightStop.

Not plausible

Unplausible: No connection found (9)

Implausible, because no path leg (or sequence of path legs) could be found meeting the given validity check criteria.

Table 299: Status indicators for the post-survey leg

Table 300: Status indicators for the entire survey data record

Status indicators for the entire survey data record (G)

Untreated (0)

Not processed

Plausible

Plausible: Corresponds to the specifications (1)

All of the sections (pre-survey leg(s), post-survey leg(s) and/or survey path leg) are plausible.

Not plausible

Unplausible: No connection found (9)

Implausible because of one (or more) implausible sections (pre-survey leg(s), post-survey leg(s) and/or survey path leg).

Unplausible: Required walk links missing (10)

Unplausibe, as path legs are plausible, but walk links in between are not. The same applies for missing transitions between stop areas.