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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 doesn’t 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
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APC University Houston, TX Summary
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