Fitchburg Line Trains at Waltham

MBTA Commuter Rail (operated by Keolis) Fitchburg Line Trains No. 406 and 407 are seen at Waltham Station. The Fitchburg Line is the former Boston & Maine Railroad route to Mechanicville, New York (north of Albany) and includes the famous Hoosac Tunnel near its western end. The route connects with the Connecticut River Line (today's Amtrak Knowledge Corridor) in Greenfield, and with the Green Mountain Railroad in North Bennington, Vermont. Passenger service west of Gardner has not existed since the formation of the MBTA, and service was cut back even further to Fitchburg in the early days of the agency due to the poor condition of the tracks. Proposals to re-extend service to Gardner and possibly even Athol or Orange have been entertained off and on over the years, but the consensus is currently that such an extension would be impractical and not financially responsible, as the steep grades over Wachusett Mountain between Fitchburg and Gardner would severely limit train speeds, making it not competitive to driving. In 2018, a new station opened at the base of Wachusett Mountain that serves as a suburban park-and-ride, which the Fitchburg terminus lacked due to the fact that it is located in an historic downtown district and also serves local bus connections.
The section of the Fitchburg Line west of Ayer Junction is also part of the primary freight transportation corridor for New England. This corridor runs from the Selkirk Intermodal Facility south of Albany, across northern Massachusetts, and ultimately up into New Hampshire and Maine. The vast majority of cargo being transported by rail between New York City or points south and New England traverses this route, since large freight trains are banned from the Northeast Corridor through southern Connecticut due to frequent sharp curves and a high volume of passenger train traffic. CSX Transportation and Pan Am Railways (with some operations contracted to Norfolk Southern) run several trains per day along this stretch of railroad, and because commuter trains have to share a single track with short passing sidings with freight trains, delays to Fitchburg Line trains have been common. To help mitigate the impact of this, starting in 2023 Keolis revised operations on the line to have roughly every other train terminate in Littleton, one stop south of the junction with the freight line, instead of continuing all the way to Fitchburg and Wachusett. There is little to no freight traffic between Littleton and Boston, meaning that commuter rail performance is generally better. This change allows for more frequent service where possible, and also mitigates the impacts of delays to the trains serving the outer reaches of the line, since passengers at the inner stops now have additional service options.
Waltham Station seen here is also unusual in that the station has two platforms, but instead of being directly across from each other (one on each side of the railbed), they are on a vertical alignment separated by a grade crossing. This means that inbound and outbound trains stop in completely different locations on different sides of the road, so it's important to make sure you are standing on the correct platform before the train arrives, since being in the wrong location isn't just a simple "up and over to the other side" as it is at most stations.