self driving carpools (and MBTA debt)
You don't have to wait until every last automobile in North Adams gets upgraded to self driving to get self driving cars to make a difference with highway congestion.
Consider what happens if you simply assign 1000 self driving cars to a single congested highway corridor.
(Tesla expects their average weekly production in 2015 to be around 1000 vehicles. They'll probably be doubling that every year or two for at least the next several years.)
Let's asume those cars are fully autonmous and can each travel to four different residential addresses to form a carpool. (In the US, carpooling currently seems to take two forms: one is that you have a fixed travel time every weekday with a fixed set of people you always travel with; and then there's casual carpooling. People considering the former tend to decide they need a single occupancy vehicle if they might need to leave work early on rare occasions for childcare, or might need to stay late occasionally to finish a long task, and the latter seems to have fixed pick up / drop off points that could just as well be served by 40' buses driven by transit agency employees. It's likely that the computerized driving will provide more flexibility for carpools to be different each day so that carpoolers can leave work at whatever time is convenient.)
If we distribute the 1000 self driving vehicles across two consecutive peak hours in the morning commute and two consecutive peak hours in the evening commute, that's 500 vehicles per hour and 2000 people per hour. If we ignore the possibility of self driving cars following more closely than human drivers can safely manage, and set a goal of 1500 vehicles per hour (which I believe is what the Boston MPO's I-93 north of Boston HOV study concluded a lane could carry while operating efficently), we can have 500 self driving carpool vehicles plus 1000 conventional vehicles per hour sharing a lane, carrying 3000 people per hour, double what we would have gotten in a conventional well flowing SOV lane, and the capital cost at $70,000 per base Tesla Model S times 1000 vehicles is around $70 million.
Maybe you can just ask the Boston MPO whether they can figure out how to build another lane for $70 million, but that also fails to take into account that each $70,000 carpool Tesla replaces four vehicles that probably would have cost 4 x $20,000 or more, and then buying electricity for the Tesla is going to cost a lot less than buying gas for the $20,000 cars, so instead of trying to charge the $70 million to the concrete budget, you might be able to just have it replace what people were going to spend on their cars anyway.
Some of these assumptions might be slightly off; I believe there are a few places in the traffic counts published on the CTPS website where actual lanes in Massachusetts actually handle 2000 vehicles per hour, and some of the Tesla carpool vehicles would probably be occupied by people who are currently carpooling in $20,000 vehicles and putting up with inflexibility as to when they leave work. But on the other hand, I haven't been exploring the possibility of the Tesla carpool vehicles operating at 1 second or .5 second headways instead of roughly 2 second headways (are we allowed to say headways when we're talking about highway following distance and not transit?) or the possibility that the $35,000 Tesla might materialize. And if a new lane is an HOV/T lane where there previously was no HOV lane, perhaps some new conventional carpools would form, but the traffic counts I remember seeing for the HOV lane on I-93 through Somerville suggest that it's only at about half capacity at the peak hour; if you simply got everyone currently using that lane to switch to Teslas that wouldn't be much of a win, so maybe there you'd need 3000-5000 self driving carpool vehicles to really make a difference there. Then again, currently two people in the vehicle counts as a carpool, and I'm thinking about what happens with carpools that would typically have four people per vehicle.
And I'm not sure how there's any difference between ``MBTA'' debt and ``Massachusetts'' debt when we consider who is ultimately responsible for paying for it.
