Does anybody know how exactly these will phase in? Part of the order is fleet expansion, part is fleet replacement. Will they start removing old cars from service immediately or will the first 3-4 new train sets add to the fleet to get the immediate capacity boost?
It'll phase in the same sequence the Blue Line 0700's did.
1. You'll have 2-3 six-car sets sprinkled into revenue service for revenue burn-in testing, with no displacements on the old fleet. Few and far between, and you may not see them at all on the off-peak as they'll be taking data collection. This scarcity will last a few months as testing is the primary goal.
2. Then you'll see more of them graduate into revenue service, and a few old sets idled for certain peak shifts but still taking turns other times. So while the new cars are now starting to take up a portion of regular fleet %, because they still have to pass warranty milestones and because any fleet-wide problems may cause all of the newbies to be pulled at once for inspection they still have to have a full-service old fleet. This stage is where you'll start to see customer service tweaks in the ASA, speaker volume, door timings, hanging straps, etc. start to be applied in the very newest cars, as well as small fixes for things like rattles and ill-fitting plastic that only showed themselves after lots of burn-in. For a brief spell you'll be able to tell the very newest cars hot-off-the-press from the very first revenue pilot cars, because the pilots will still be carrying some of the first-timer annoyances that won't be modded out until midway through deliveries (example: The very talky ASA on the Blue 0700's was extremely, rage-inducingly annoying on the first revenue pilots until they toned Frank's verbosity down a notch in the later deliveries, then bumped the ASA firmware on the pilots to match.)
3. Old cars will start being idled at Wellington by order of sorriest condition, as the new car numbers swell. They still have to be maintained enough to go back into service on days' notice (but not hours) if there's some catastrophic fleet-grounding flaw in the new cars, but day-to-day maintenance starts getting curtailed and parts start getting raided from the reserve line to patch the shrinking in-service fleet so these are the de facto first retirees. The 01200/01300's are currently all in-service in similar overall condition, so there's no junkers leaps-and-bounds worse than the rest where you'd be able to guess at first retirees. Most likely things like snow casualties or crap-outs on the hardest-to-find parts set the order of removal from service.
4. Yard space will be at premium and enough warranty milestones will be passed that it's time to start removing the out-of-service reserves from the property. Cars are stripped of some key usable parts universal to the rapid transit division or which can feed the Red Line 01500/01600/01700's for a couple more years, and combed for some good-condition fixtures like rollsigns and over-the-door maps to re-sell through the gift shop. With the Blue 0700's and Flyer trackless trolleys they were taken by flatbed truck to Billerica Shops to pile up until whoever won the scrap contract could take them. Removal from the home yard is considered the "official" point of retirement, since they've now been stripped enough to be no trivial matter to get running again and are scrapper responsibility for removing from the temporary boneyard.
5. The final old units remaining in-service are any that have underwriter refinancing/leaseback deals, which are a common insurance money-saving scheme for railcars of all types. For example, the final 24 Blue Line 0600 cars that still ran alongside the full-delivered 0700's for several months were ones that had underwriter contracts that hadn't expired, and thus had to be maintained ready-to-run for the duration of that contract. And a number of Boeing LRV's remained at Riverside 3+ years after their last run to wait out expiring leases. I don't know how many Orange cars are under these lease-back deals. Usually (but not always) if they are on leaseback there'll be a nameplate for the underwriter affixed near the manufacturer builder's plate by the operator door.
5a. The overlap between full
replacement fleet delivery and running out the clock on the old 012/013's that have leasebacks would be first opportunity to expand service. New cars will still be actively delivered for the expansion order, but they now have enough active reserves to scale-up. It depends on how many more months the leaseback 012/013's have to malinger on, and whether parts scarcity makes that a good idea to push them. With the Blue 0600's, they ended up being pulled from service and placed in dead storage at Orient Heights well before the lease terms ended on those cars simply because they were too unreliable and bereft of spare parts to keep running in limited service. If I had to guess, the T's experience with the last Blue 0600's will make them gun-shy about using the last leaseback Orange 012/013's as the service expander. More likely they'll wait for enough new cars on the expansion order to arrive and get themselves on a homogeneous fleet before cranking up the service levels. Lease expiration games probably mean that 1-2 dozen old cars will remain in the Wellington dead-line rostered but out-of-service for up to 2 years after final revenue appearance, then end up getting covered on a separate scrap contract (probably rolled in with some of the first Red Line scrappings).
6. Seashore Trolley Museum and any other interested museums get their pre-negotiated cars out of this remainder dead line. I don't know if there are any individual cars in the Orange fleet with unusual historical significance, other than they'd probably try to set aside first units 01200/01201 for Seashore. Some cars from these leaseback remainders may also be retained for non-revenue service as work trains. A bunch of the predecessor Orange 01100's ran for 6 extra years on the work trains for both Orange AND Red (the platform gap on Red obviously not being a problem for the overnight shift). And the 4-car set of Red 01400's lasted nearly 20 years on the overnight trash train until their propulsion finally crapped out and they moved into storage at Codman Yard. Orange badly needs more dedicated work equipment, so this is a cheap way to address that need even if there are no guarantees for further longevity of the designated work sets beyond "run 'em till they can't run no more".