This vignette highlights some known limitations or bugs with OpenTripPlanner as well as suggested solutions.
If you find OTP can not find a route here are some common reasons to check:
OTP will snap fromPlace and toPlace coordinates to the road network, but only for a limited distance. If your points are far from the road network (e.g. in a lake or middle of a park) then OTP will fail to find a route.
OTP does not support all mode combinations (e.g. walk + drive) so some places may only be accessible by certain modes. For example, you can’t walk on a motorway or drive on a path. Use the debug layers to check for mode restrictions.
By default, OTP caps the maximum walking distance to a transit stop at a low level, so some areas are unreachable by transit. Increase the maximum walking distance to get better results.
A known bug that stops driving on any road with cycling infrastructure. https://groups.google.com/forum/#!topic/opentripplanner-users/BOv1J32k6Sc
If you are doing a large amount of routing consider the following options.
It is common for GeoTIFF to have a no data value often the maximum possible value. OTP can misinterpret this as an elevation value. So set your no data values in your elevation data to something more plausible like 0.
Note that OTP does not support all types of GeoTIFF compression so you may have to change the compression type of the image if you are experiencing problems.