That page hasn't been updated in a while.The MBTA has 14 new Orange Line train sets it lists as “active service” but they’ve only ever had 10 on route at once. Is this because of the operator/dispatcher shortage or just service cuts for budgeting reasons?
Barring some insane miracle, I don't see any way the Orange Line order is done this year and neither does anyone else.
Presumably, they meant up to 14 new train cars whenever this was last updated (out of 18 train cars/3 sets at that time). It doesn't even make sense since they can't ever have only 14 cars out because each set has 6 train cars.
They are up to 82 cars delivered, which is enough for 13 sets plus 4 additional cars. However, 4 of those cars are not yet accepted for passenger service (1478 through 1481, which have been seen out in the wild testing this week), and an additional 2 cars (1400 and 1401) have been out of service for 2 years due to derailment damage sustained in March of 2021. 1400 and 1401 are just sitting in Wellington Yard, possibly awaiting repair at the end of the contract.
So, the reason you aren't seeing 14 sets is because they do not physically have 14 sets of new trains. I believe they also are only approved to run 13 sets at the maximum right now due to the dispatcher shortage; they had originally planned to run some old trains during peak hours at the beginning of the winter schedule to help meet this but that plan was scrapped or at least put on hold. That leaves them with 12 sets plus 4 spare cars in active (of new trains); they try to have 2 spare sets in the yard at any given time, which brings them down to up to 10 sets on the tracks (which was the original peak-hour limit when the dispatching issues first began). In a few rare instances, 11 sets have been in revenue service at once for brief amounts of time but typically one set will go out of service at Wellington shortly thereafter.