maxTransfers cannot be changed by scripts and different default than web interface

[lapseofreason]

The default maxTransfers should be the same in scripting and web interface, preferably a value of at least 4 (at least in my use case). Moreover, it would be useful to be able to configure it in scripts (see patch below).

I am running OTP in scripting mode (jython). When comparing its results to results from the web interface and to Google Maps, I noticed very long walking distances. The resulting total time is way over the actually needed time. After a lot of searching I found out that this is due to maxTransfers being set to 2 for scripts, whereas it is 4 for the web interface.

Affects OTP v1.2.0.

Patch to set maxTransfers and maxTransferWalkDistance in Scripts:

--- a/src/main/java/org/opentripplanner/scripting/api/OtpsRoutingRequest.java
+++ b/src/main/java/org/opentripplanner/scripting/api/OtpsRoutingRequest.java
@@ -91,6 +91,14 @@ public class OtpsRoutingRequest {
         req.maxWalkDistance = maxWalkDistance;
     }
 
+    public void setMaxTransferWalkDistance(double maxTransferWalkDistance) {
+        req.maxTransferWalkDistance = maxTransferWalkDistance;
+    }
+
+    public void setMaxTransfers(int maxTransfers) {
+        req.maxTransfers = maxTransfers;
+    }
+
     public void setWheelchairAccessible(boolean wheelchairAccessible) {
         req.wheelchairAccessible = wheelchairAccessible;
     }

[laurentg]

This looks OK to me, do you mind making a PR with this change?

[lapseofreason]

Here you go: #2508

What do you think about changing the default for maxTransfers to 4 or 5? Why did you choose 2 as the default in the first place? A reasonable route here would be bus to local station, train, connecting train and then a local bus to the final destination. Many reasonable routes are thus prohibited by a maximum of 2 changes and result in ridiculously long travel with several miles of walking.

[abyrd]

On 9 Nov 2017, at 20:25, lapseofreason ***@***.***> wrote: What do you think about changing the default for maxTransfers to 4 or 5? Why did you choose 2 as the default in the first place?

I think the value of 2 is just hard-wired into the initialization of the request object. I don’t think there’s any special reasoning behind this. At the geographic scale at which OTP was being used, more than 2 transfers was rare and most people wouldn’t like it. Now OTP is used at larger scales so you might want to set it higher.

A reasonable route here would be bus to local station, train, connecting train and then a local bus to the final destination. Many reasonable routes are thus prohibited by a maximum of 2 changes and result in ridiculously long travel with several miles of walking.

Actually as I hinted in an earlier email, I believe that the current default router configuration makes transfer limiting invalid from an algorithmic perspective. It doesn’t seem to be causing highly visible problems (since it’s defaulting to 4 transfers in common usage) but it could in theory cause buggy paths. We should probably just switch it off entirely. Andrew

[lapseofreason]

since it’s defaulting to 4 transfers in common usage

I would be in favour of making this the default for the scripting interface too then.

I imagine it would be a common way to try some routes in the web interface first and then write a script to automate the calculations. Any differences between the two will probably trip people as they did me. Finding the cause of those differences took me a long time, probably I'm not the only one.

[abyrd]

Looks like @laurentg merged PR #2508, closing this ticket.