The MBTA's handful of express routes are routes that travel from some of the furthest edges of the MBTA area along the highway with direct service to downtown. Sounds like a normal express route. Well, there is an exception to that... the 351.
The 351 used to not be an exception at all. Prior to 2020, the 351 used to run from Bedford Woods in Bedford, through Burlington, and along the highway to Alewife, where transfers are available to other bus routes and the Red Line. The route was temporarily suspended until August 2021, when it was brought back in its current form (the 351 I'll be discussing here).
The 351 connects a few office parks in Bedford with a shopping plaza in Burlington. Not the Burlington Mall, that's served by the 350. All that for a $4.25 express bus fare.
For a route that is a reverse-commute office park shuttle, I'm actually quite surprised by the schedule. I thought this would be a few trips at peak hours (morning to the offices, afternoon from the offices). The route still runs during peak hours, actually between 6 and 9 am, as well as between 3 and 6 pm. In both directions. On top of that, the route runs every 20 minutes during those hours.
But this isn't just an anomaly as an express route. The T has a number of other suburban routes, some of which I took a brief look at, and the 351 is an anomaly as a suburban route. The other suburban routes are either express routes, or terminate at one of the T's bus hubs. The 351 terminates at a small shopping plaza. The only other connection is the 350, which travels locally through Woburn and Winchester to Alewife. It's not too far from the 354, but that's an express to downtown.
In it's current form, I'm not sure if the 351 still needs to be operated by the MBTA. Given its local routing in Burlington and Bedford, this route might be better off as an LRTA route. The 351 parallels the LRTA 14 for the entire duration. The LRTA 14 ends up continuing north towards Lowell and stops at the same office parks as the 351. It's nice that these office parks are being served by transit, but the MBTA might be wasting resources operating these 351 runs. The only reason I see that could be why the MBTA operates this is transfers. I've never ridden the 351, but there may be a number of passengers transferring from the 350 in Burlington who don't want to pay an extra fare transferring between the MBTA and LRTA.