US9 was truncated (in TM) back to the I-87 ramps in Nov 2015 per the linked issue.
At that time, the endpoint was moved farther south on the east service road, to the NB ramps, with no graph connection to I-87. I was considering the west service road as a separate road, not a part of southbound US9.
Now, I've relocated the endpoint to the same coords as the I-87 interchange, counting the west service road as part of SB US9.