Origin and Destination
The O/D module allows traffic planners and consultants to assess vehicle movement patterns in areas of interest.
Strict trips vs. Passthrough in O/D
Strict trips start or end at the Origin or Destination, while Passthrough trips involve passing through without stopping at these points.
Strict trips
Strict trips are those that began or ended in the Origin and Destination (O/D). Strict trips are the ones marked as "Start/end here only" in the UI. A strict trip will also likely pass through the Origin or Destination, but trips are only categorized as Passthrough if the vehicle does not stop at the Origin or Destination.
Passthrough
If an Origin or Destination are defined to have Passthrough behavior, the start of the journeys are considered at the road segment taken upon exit of the Origin and the end of the journey is taken at the first road segment upon entry of the Destination.
Passthrough analysis is only available for trips where the geography of interest is on-road. If the geography of interest is off-road, we cannot do a passthrough analysis.
Overlapping zones
If zones in an analysis overlap, a trip is defined for every applicable zone pair. This means a single physical trip may be counted multiple times in the final output.
Journey filters
Filtering a journey allows you to customize your analysis to provide data that is most relevant to you.
Trip Chaining
Control how a journey is defined and what is included in your trip chaining analysis.
Trip Chaining on the O/D Journey Filters refers to controlling how a journey is defined and what is included in your trip chaining analysis.
To be considered a candidate for trip chaining, the observed trips must end and start within 100 meters of each other, and any subsequent trip must be within 24 hours of the first trip.
Note:
This disproportionately applies to dense urban centers where the GPS signal bounces – and is highly localized where it impacts the analysis.
Trip Chaining Parameters
Each parameter influence the results of an Origin and Destination.
| Altitude Name | API Name | Description | Dependencies |
|---|---|---|---|
| Trip Chaining Threshold | tripChainDuration | Chain consecutive trips together by ignoring stops under a determined number of minutes. | N/A |
| Include Sub-Journeys | retainSubJourneys | When set to true, each intermediate stop within a chained journey is counted as a separate journey in the OD matrix, in addition to the full chained journey. When set to false, only the full origin-to-destination chained journey is counted. Does not apply to passthrough destinations. | N/A |
| Chaining Within Origins | tripChainWithinOrigin | Metrics account for trips chained within an Origin. Deselecting this will consider the last trip in the Origin as the journey start. | If not selected, makes Include Inbound Chaining mandatory. |
| Include Inbound Chaining | retainBackwardChainingOrigin | When set to true, the OD matrix includes journeys where the vehicle's stop duration at the initial origin is shorter than the trip chaining threshold, meaning the origin may have been a mid-chain stop rather than the true start of the trip. When set to false, these journeys are excluded. | N/A |
| Chaining Within Destinations | tripChainWithinDestination | Metrics account for trips chained within a Destination. Deselecting this will consider the first trip in the Destination as the journey end. | If not selected, makes Include Outbound Chaining mandatory. |
| Include Outbound Chaining | retainForwardChainingDestination | When set to true, the OD matrix includes journeys where the vehicle's stop duration at the final destination is shorter than the trip chaining threshold, meaning the destination may have been a mid-chain stop rather than the true end of the trip. When set to false, these journeys are excluded. | N/A |
Note:
Both the UI and API defaults effectively result in no trip chaining. The API defaults retainBackwardChainingOrigin, retainForwardChainingDestination, and retainSubJourneys to true, but also defaults tripChainDuration to 0, which means trip chaining never activates regardless of the retain parameter values. The Altitude UI always explicitly sends false for all three retain parameters. In both cases, the retain parameters only take effect once tripChainDuration is greater than 0.
Trip Chaining Scenarios
The following scenarios can help users better understand how each parameter may influence the results of an Origin and Destination.
Trip Chaining Scenario 1
The following scenario demonstrates how each parameter may influence the results of an Origin and Destination.
| Altitude Name | API Name | Selection |
|---|---|---|
| Chaining Within Origins | tripChainWithinOrigin | True |
| Chaining Within Destinations | tripChainWithinDestination | True |
| Include Inbound Chaining | retainBackwardChainingOrigin | N/A |
| Include Outbound Chaining | retainForwardChainingDestination | N/A |
| Include Sub-Journeys | retainSubJourneys | False |
Journey (trips that comprise the journey)
| O/D Pair | No trip chaining | Trip Chaining Threshold: 10 min | Trip Chaining Threshold: 15 min | Trip Chaining Threshold: 20 min |
|---|---|---|---|---|
| X → Y | ✘ | ✔ (a, b, c) | ✔ (a, b, c) | ✘1 |
| X → Z | ✘ | ✘ | ✘ | ✔ (a, b, c, d, e, f) |
| Y → Y | ✔ (d) | ✘2 | ✘ | ✘ |
| Y → Z | ✔ (e) | ✔ (d, e) | ✔ (d, e, f) | ✘3 |
1 Journey dropped as retainSubJourneys is set to False and trips a, b, c, d, e and f are included as part of X → Z.
2 Journey dropped as retainSubJourneys is set to False and trip d is included as part of Y → Z.
3 Journey dropped as retainSubJourneys is set to False and trip d is included as part of Y → Z.
Trip Chaining Scenario 2
The following scenario demonstrates how each parameter may influence the results of an Origin and Destination.
| Altitude Name | API Name | Selection |
|---|---|---|
| Chaining Within Origins | tripChainWithinOrigin | False |
| Chaining Within Destinations | tripChainWithinDestination | False |
| Include Inbound Chaining | retainBackwardChainingOrigin | N/A |
| Include Outbound Chaining | retainForwardChainingDestination | N/A |
| Include Sub-Journeys | retainSubJourneys | False |
Journey (trips that comprise the journey)
| O/D Pair | No trip chaining | Trip Chaining Threshold: 10 min | Trip Chaining Threshold: 15 min | Trip Chaining Threshold: 20 min |
|---|---|---|---|---|
| X → Y | ✘ | ✔(b, c)1 | ✔ (b, c) | ✘ |
| X → Z | ✘ | ✘ | ✘ | ✔ (b, c, d, e)2 |
| Y → Y | ✔ (d) | ✔ (d)3 | ✔ (d) | ✘ |
| Y → Z | ✔ (e) | ✔ (e)4 | ✔ (e) | ✘ |
1 Journey does not include trip a since tripChainWithinOrigin is set to False.
2 Journey does not include trips a and f since tripChainWithinOrigin and tripChainWithinDestination are set to False.
3 Journey remains since tripChainWithinOrigin is set to False and trip d cannot be included as part of Y → Z.
4 Journey does not include trips d and f since tripChainWithinOrigin and tripChainWithinDestination are set to False.
Trip Chaining Scenario 3
The following scenario demonstrates how each parameter may influence the results of an Origin and Destination.
| Altitude Name | API Name | Selection |
|---|---|---|
| Chaining Within Origins | tripChainWithinOrigin | False |
| Chaining Within Destinations | tripChainWithinDestination | False |
| Include Inbound Chaining | retainBackwardChainingOrigin | N/A |
| Include Outbound Chaining | retainForwardChainingDestination | N/A |
| Include Sub-Journeys | retainSubJourneys | True |
Journey (trips that comprise the journey)
| O/D Pair | No trip chaining | Trip Chaining Threshold: 10 min | Trip Chaining Threshold: 15 min | Trip Chaining Threshold: 20 min |
|---|---|---|---|---|
| X → Y | ✘ | ✔ (b, c)1 | ✔ (b, c) | ✔ (b, c)2 |
| X → Z | ✘ | ✘ | ✘ | ✔ (b, c, d, e)3 |
| Y → Y | ✔ (d) | ✔ (d) | ✔ (d) | ✔ (d)4 |
| Y → Z | ✔ (e) | ✔ (e)5 | ✔ (e) | ✔ (e)6 |
1 Journey does not include trip a since tripChainWithinOrigin is set to False.
2 These journeys are included since retainSubJourneys is set to True.
3 Journey does not include trips a and f since tripChainWithinOrigin and tripChainWithinDestination are set to False.
4 These journeys are included since retainSubJourneys is set to True.
5 Journey does not include trips d and f since tripChainWithinOrigin and tripChainWithinDestination are set to False.
6 These journeys are included since retainSubJourneys is set to True.
Trip Chaining Scenario 4
The following scenario demonstrates how each parameter may influence the results of an Origin and Destination.
| Altitude Name | API Name | Selection |
|---|---|---|
| Chaining Within Origins | tripChainWithinOrigin | True |
| Chaining Within Destinations | tripChainWithinDestination | True |
| Include Inbound Chaining | retainBackwardChainingOrigin | N/A |
| Include Outbound Chaining | retainForwardChainingDestination | False |
| Include Sub-Journeys | retainSubJourneys | False |
Journey (trips that comprise the journey)
| O/D Pair | No trip chaining | Trip Chaining Threshold: 10 min | Trip Chaining Threshold: 15 min | Trip Chaining Threshold: 20 min |
|---|---|---|---|---|
| X → Y | ✘ | ✔ (a, b, c) | ✔ (a, b, c) | ✘1 |
| X → Z | ✘ | ✘ | ✘ | ✘ |
| Y → Y | ✔ (d) | ✘2 | ✘ | ✘ |
| Y → Z | ✔ (e) | ✔ (d, e) | ✘3 | ✘ |
1 Journey does not exist because the retainForwardChainingDestination parameter is set to False, so if the last trip leaves the destination, Zone Y, below the Trip Chaining Threshold, the entire journey is dropped.
2 Journey does not exist because retainSubJourneys is False, tripChainInOrigin is True, and the trip d is included in the larger Y → Z journey.
3 Journey does not exist because the retainForwardChainingDestination parameter is set to False, so if the last trip leaves the final destination, Zone Z, below the Trip Chaining Threshold, the entire journey is dropped.
Trip Chaining Scenario 5
The following scenario demonstrates how each parameter may influence the results of an Origin and Destination.
| Altitude Name | API Name | Selection |
|---|---|---|
| Chaining Within Origins | tripChainWithinOrigin | True |
| Chaining Within Destinations | tripChainWithinDestination | True |
| Include Inbound Chaining | retainBackwardChainingOrigin | False |
| Include Outbound Chaining | retainForwardChainingDestination | N/A |
| Include Sub-Journeys | retainSubJourneys | False |
Journey (trips that comprise the journey)
| O/D Pair | No trip chaining | Trip Chaining Threshold: 10 min | Trip Chaining Threshold: 15 min | Trip Chaining Threshold: 20 min |
|---|---|---|---|---|
| X → Y | ✘ | ✔(b, c) | ✘1 | ✘ |
| X → Z | ✘ | ✘ | ✘ | ✘2 |
| Y → Y | ✔ (d) | ✘3 | ✘ | ✘ |
| Y → Z | ✔ (e) | ✔ (d, e, f) | ✔ (d, e, f) | ✘4 |
1 Journey does not exist because the retainBackwardChainingOrigin parameter is set to False, the stop duration prior to trip b is below the Trip Chaining Threshold, and the trip prior (a) started outside the zone.
2 Journey does not exist because the retainBackwardChainingOrigin parameter is set to False, the stop duration prior to trip b is below the Trip Chaining Threshold, and the trip prior (a) started outside the zone.
3 Journey dropped as retainSubJourneys is set to False and trip d is included as part of Y → Z.
4 Journey does not exist because the retainBackwardChainingDestination parameter is set to False, the stop duration prior to trip d is below the Trip Chaining Threshold.
