For those of you who are interested, I've been able to piece together what happened just so you can see how the situation developed and how it was mitigated.
Thursday's P521, the 5:05 PM outbound express from South Station, is the same set of equipment that is used for the next morning's P508. While outbound through Westboro and Grafton and to Worcester, it encountered a problem with the locomotive (which was #1072). Rumors indicate it had a problem with a traction motor.
At some point overnight that locomotive (#1072) was swapped out with a different locomotive (#2004). I only mention this here because some folks might be wondering if the problems from Thursday night were the reason for the Friday morning problems - and as far as I can tell, the problems were unrelated.
That brings us to this morning (Friday 5/12/2017). The first indication of trouble came across at 6:43 AM when T-Alerts alerted that P508 would be delayed due to a mechanical problem. Indications are that locomotive #2004 had a failed Head End Power (HEP) unit and a failed air compressor. Learn about the HEP in the glossary, but the important point is that the train can't operate without a functioning air compressor - since the brakes use that compressed air!
Without reproducing the entire schedule, which is available here, the relevant movements from Worcester after 6:45 AM are:
P508 departs 7:00 AM (using Thursday's P521 equipment from the layover yard)
P510 departs 7:30 AM (using the equipment from P503 arriving Worcester at 7:07 AM)
P552 departs 8:05 AM (using the equipment from 'deadhead' (no passengers) outbound 6501, arriving Worcester around 7:40 AM)
The layover yard at Worcester has capacity for 4 train sets. Those 4 train sets are used for P500, P502, P504, and P508. After 6:30 AM, the only set in the layover yard is for P508. This is relevant because it shows that there was no 'spare' set (or even just a locomotive) available in the layover yard to be substituted for the dead P508.
Once P508 was determined to be dead and unavailable, the scramble started to 'cover' the trip with other equipment and keep all of us passengers somewhat close to on time.
The only reasonable solution was to use the P503/P510 equipment as P508. There was no other equipment within 40 minutes of arriving at Worcester (and 6501 is an even smaller capacity set than P503/P510). It's also not reasonable to switch out a locomotive from a 'good' set and tack it onto the intended P508 set. Because of the arrangement of the layover yard and switches at Worcester, that would have required multiple connections, disconnections, and shifting movements. It would have taken an hour.
Using the P510 equipment as P508 presented a capacity problem, since the P503/P510 set had only 3 doubles and 2 flats while P508 usually has 8 doubles. The numbers:
8 doubles = capacity of 1,440
3 doubles + 2 flats = capacity of 768
In 2016, P508 had documented daily ridership of over 1,600 passengers - that's correct, documented ridership above the capacity of the usual train set. [Hence the reason for my petition last year and the change of P506 to an express train starting in 2 weeks...if you're reading this and you usually take P508, consider switching to P506 after 5/22! I digress.]
This explains the flurry of T-Alerts warning about reduced capacity and delays. Fridays typically have lower ridership than other weekdays, but everyone knew once the P510 set was substituted for P508 that capacity was going to be a problem.
The new P508 using the P510 equipment departed Worcester at 7:13 AM - only 13 minutes late, but with the expectation of capacity issues down the line.
With the P510 equipment being used for P508 - leaving the Framingham-Worcester line short one set - Keolis had to make some quick decisions. The options available were the cancellation of P510 (or another Worcester or Framingham originating train) or the use of a spare set to keep all the trains operating.
The normal service plan for Commuter Rail includes one spare set stationed in Boston to cover any problems on any of the South Side lines. Earlier this spring, when the equipment shortage was most severe, that spare set was used in normal revenue service - meaning there were no spares. Luckily for us, there was a spare available and it was sent out to help.
After 7 AM, with the Worcester layover yard empty, all the inbound trains have to be 'turns' of outbound equipment. There are no sets that layover in Framingham, so all of the Framingham inbound trains 'turn' from outbound equipment. The normal outbound sequence after 7 AM is:
P503 arrives Worcester at 7:07 AM - becomes P510.
6501 arrives Worcester at 7:40 AM - non-revenue deadhead move of equipment from Boston to Worcester for use as P552 (Heart To Hub).
P585 arrives Framingham at 7:32 AM - becomes P584.
P505 arrives Worcester at 8:24 AM - becomes P512.
Keolis made the following adjustments:
The 6501 equipment was held in Framingham and became P584.
P585 went to Worcester and became P552 (Heart to Hub)
The extra set went to Ashland and started from Ashland as delayed P510.
Why did they shuffle 6501 and P585? That's not clear to me, but it could have been due to set size - an attempt to get the set with the larger capacity into a position to take the trip with the higher expected ridership. It does appear that holding 6501 in Framingham prevented the extra set from proceeding west past Framingham due to the traffic congestion at Framingham - hence the reason why it was only able to get to Ashland (not Southboro or further west) to originate there as P510.
The 7:45 AM - 7:50 AM time is a critical moment in Framingham with the usual arrival of P585 & P508 along with the departure of P584. As many Framingham riders are aware, a delayed P508 can result in confusion about which train will leave first - P508 or the local P584.
This morning, the line-up at 7:50 AM appears to have been:
P508 at Ashland operating about 20 minutes late and getting very full.
P585 past Framingham and continuing outbound to Worcester to become P552.
6501 standing by at Framingham to become P584.
The extra set standing by east of Framingham waiting to get past the traffic in Framingham to go west.
As expected, there was significant confusion at Framingham with 6501/P584 on track 1 (the "outbound" track) but waiting for P508 to pass before departing Framingham. There were some reports of P508 passengers being left on the platform at Framingham, and MOST passengers waiting for P508 at West Natick were NOT able to board P508. A fellow Framingham-Worcester posted this picture of the conditions on P508:
The remainder of the commute proceeded as expected, with cascaded delays for everything after P508. Final answers:
P508 arrived South Station about 25 minutes late.
P584 arrived South Station about 25 minutes late.
Note: If you intended to take P508 but couldn't get on due to overcrowding, you actually got to Boston 50 minutes late (vs. your intended arrival time).
P510 arrived South Station about 20 minutes late.
P552 arrived South Station about 20 minutes late.
Note: if you intended to take P510 from Grafton, Westboro, or Southboro, you ended up on P552 and were about 40 minutes late (vs. your intended arrival time).
P586 arrived South Station about 10 minutes late.
Could Keolis have done anything better? Hard to say, but considering the largest set broke down without a replacement immediately available, keeping everyone delayed less than an hour has to be a minor success. I'm not sure about the 6501 / P585 shuffle - if they had kept 6501 going to Worcester it could have become a delayed P510 from Worcester. P585 could have continued to Worcester to become P552, and the extra could have been used as P584. That would only have reduced the delay for the P510 passengers from Grafton, Westboro, and Southboro - everyone else probably would have had similar delays to what actually happened. And I'm not clear on set size decisions, so that might have been why they did what they did and they might have made good decisions.
An argument can be made that P508 should not have even tried to stop at Framingham or West Natick to attempt to squeeze more passengers on board. They could have gotten on P584. That's a valid point. I think that Keolis and the MBTA are reluctant to have trains skip scheduled stops due to the possibility of 'interzone' passengers becoming trapped on a train past their station.
Also important to note that P508 was able to operate express ahead of P584, which helped to reduce the delay for P508 passengers - otherwise the delay for them could have been an hour.
Clearly it would have helped us to have a spare set standing by in Framingham or Worcester. That just isn't possible with the equipment inventory that the MBTA owns - and note that it is the MBTA that owns and allocates equipment, NOT Keolis. So perhaps call your legislator and invite them to increase funding for Commuter Rail so we can have more spare sets.