There was an NHDOT virtual public meeting last night regarding the Capitol Corridor Project/NH Commuter Rail extension. I only caught the end of it so I don't have much information to share, however they said the presentation slides would be uploaded within the week, and I'll be sure to post them when they're released.
During the presentation it was said that they are aiming to submit an FTA application for the project by "late 2022", and that construction would take "approximately 3 years" once the application was approved.
No new stations in Massachusetts are currently planned as part of the project. (However I would certainly expect North Chelmsford, UMass Lowell, and maybe even Tyngsborough stops to be added later as infill stations if the project is completed)
It was also mentioned that 12 new bi-level coaches are planned to be purchased as part of the project. No new locomotives are planned to be purchased.
One of the presenters briefly mentioned that "far-future" electrification was anticipated, and that the project is being designed with future electrification in mind.
Lastly, here is the proposed schedule.
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