APC University Sponsored By Geographic Analysis of Flagged and
Unknown Stops in APC Data David Hathaway, PE RSM Services
Corporation
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APC University Houston, TX APCs typically record the location
of each stop APC vendors then correlate locations to stops on the
pattern the vehicle is running Unknown Stops are those that fail to
correlate to a stop on the pattern Stops in APC Data
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APC University Houston, TX Flag stops driver is asked to stop
at an unofficial location as a courtesy Poor GPS locating Downtown
canyons, power lines, etc Faulty equipment Bad data Patterns
incorrectly built Stops physically moved and not updated in data
Construction forces temporary re-route Driver simply drives off the
route Mom needs a ride, right?? Causes of Unknown Stops
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APC University Houston, TX Some agencies require drivers to
stop only at located official stops Flag Stops are forbidden and
cause for work action Stops are not credited with activity
Under-performing stops might be cut in the future Areas of activity
are not recognized Locations with very frequent Flag Stops are
candidates for official stops Masks data errors Too many
off-pattern stops are a reason for trips to be discarded from
analysis (lost data?) Impact of Unknown Stops
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APC University Houston, TX Agency A: 5-6% 8,000 unknown stops
per week Agency B: 3-4% 2,800 unknown stops per week Agency C: 1%
900 unknown stops per week Agency D: 2% 1,400 unknown stops per
week How Common Are Unknown Stops?
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APC University Houston, TX Unknown stops are usually reported
by the APC system, and marked as unknown A indicator stop ID
(STOP_ID=99999 or similar) The Latitude, Longitude are reported
still These Unknown stops can then be plotted on a map to see where
they are Geographic Information Systems (GIS) is the tool that
plots data on maps Visualization is Helpful
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APC University Houston, TX Several categories of unknown stops
will be shown ArcMap 10.1 will be used to illustrate Used Ridecheck
Plus to provide data hooks Examples of Unknown Stop Types
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APC University Houston, TX How to find Hot Spots
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APC University Houston, TX How to find Hot Spots
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APC University Houston, TX Example 1: Huge Terminal
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APC University Houston, TX Example 1: Huge Terminal
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APC University Houston, TX Example 1: Huge Terminal
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APC University Houston, TX Example 1: Huge Terminal For one
week of data FOR ONE ROUTE: Boardings: 1917 Alightings: 166
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APC University Houston, TX The solution? This problem doesnt
lend itself to a great solution Symbolic stops in large facilities
are useful to manage complexity and reduce scheduler workload Some
APC vendors provide geo-fences, which define stops are areas rather
than points with radiuses Supplemental correlation: merge all
unknown stops to the nearest known stop on the pattern. Lose the
diagnostic value of unknown stops Example 1: Huge Terminal
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APC University Houston, TX Example 2: Flag Stops
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APC University Houston, TX Example 2: Flag Stops
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APC University Houston, TX Example 2: Flag Stops
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APC University Houston, TX The solution? Awareness. The agency
knows this is going on, and the relative impact of their decision
to encourage Flag Stops Because this might result in APC ridechecks
being discarded due to excessive unknown stops, this route is being
monitored to keep tabs on that Supplemental correlation of unknown
stops to nearest known stop Example 2: Flag Stops
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APC University Houston, TX Example 3: Bad Data 1
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APC University Houston, TX Example 3: Bad Data 1
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APC University Houston, TX Example Z: Bad Data 1
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APC University Houston, TX Example 3: Bad Data 1
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APC University Houston, TX Example 3: Bad Data 1
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APC University Houston, TX The Explanation Discussed this with
client, who did some head scratching Definitely Flag Stops
happening at major trip generators Stops are missing from one
database (the schedule) The patterns need some attention GIS helped
identify an area for updating Example 3: Bad Data 1
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APC University Houston, TX Example 4: Definition of
Location
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APC University Houston, TX Example 4: Definition of
Location
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APC University Houston, TX Example 4: Definition of Location
Official Stop Unknown Stops
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APC University Houston, TX Example 4: Definition of
Location
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APC University Houston, TX The Question What defines a bus
stop? Is it where the sign is, or where the traffic department
intends for the bus to stop? The Solution In this case, the agency
re-coded the stop location to be where the physical bus stop sign
(and bench) is located GIS visualization pointed to a location to
investigate Example 4: Definition of Location
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APC University Houston, TX Example 5: Bad Data 2
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APC University Houston, TX Example 5: Bad Data 2
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APC University Houston, TX Example 5: Bad Data 2
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APC University Houston, TX Example 5: Bad Data 2
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APC University Houston, TX Example 5: Bad Data 2
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APC University Houston, TX The Solution? Like other agencies,
the data for a stop is maintained in several databases. The GIS
team updated the locations in all of these. Problem solved. The GIS
tool provides a method to quickly determine problem locations.
Example 5: Bad Data 2
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APC University Houston, TX Example 6: The Cause of Groans
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APC University Houston, TX Example 6: The Cause of Groans
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APC University Houston, TX The Solution? Most of the unknown
stops were caused by on- going construction. Nothing really to do
to clean up that issue. Many of the unknown stops were the result
of bad pattern coding Example 6: The Cause of Groans