Description of the Bug
Ranch adds an unnecessary incorrect freeway loop to local bus routes, in an attempt to capture a stop node with coordinates that falls on a freeway segment. The additional loop could create unrealistically long travel times and excessive delays in the future-year transit network. This is potentially caused by limitations in the underlying Cube highway network, where stacked roadway links in the real-world network cannot be represented accurately.
Example
Ranch Routing of LA DOT Route 1758 Southeast Counterclockwise
Ranch Routing in Cube
Corrected Cube Routing
Potential Workaround
- Flag Routing Segments with Abnormal Stop-to-Stop Distances
For each transit segment, compare the stop-to-stop distance represented by the GTFS shape with the distance of the Ranch-routed path on the Cube network. Flag segments with significant discrepancies for further review. While this approach does not resolve the underlying routing issue, it helps identify problematic segments and streamlines the routing QA/QC process.
- Penalize Freeway Mid-Segment Stop Nodes for Bus Routing
Identify sequences of freeway nodes and detect nodes that are effectively located in the middle of a freeway segment (i.e. the previous node and the next node are both freeway nodes). Apply a large penalty to discourage local bus routes from selecting this node, thereby reducing the likelihood of unrealistic freeway looping during the routing process. Freeway stations that are near the ramps will be allowed.
Progress:
Description of the Bug
Ranch adds an unnecessary incorrect freeway loop to local bus routes, in an attempt to capture a stop node with coordinates that falls on a freeway segment. The additional loop could create unrealistically long travel times and excessive delays in the future-year transit network. This is potentially caused by limitations in the underlying Cube highway network, where stacked roadway links in the real-world network cannot be represented accurately.
Example
Ranch Routing of LA DOT Route 1758 Southeast Counterclockwise
Ranch Routing in Cube
Corrected Cube Routing
Potential Workaround
For each transit segment, compare the stop-to-stop distance represented by the GTFS shape with the distance of the Ranch-routed path on the Cube network. Flag segments with significant discrepancies for further review. While this approach does not resolve the underlying routing issue, it helps identify problematic segments and streamlines the routing QA/QC process.
Identify sequences of freeway nodes and detect nodes that are effectively located in the middle of a freeway segment (i.e. the previous node and the next node are both freeway nodes). Apply a large penalty to discourage local bus routes from selecting this node, thereby reducing the likelihood of unrealistic freeway looping during the routing process. Freeway stations that are near the ramps will be allowed.
Progress: