A tweet may not be worth a thousand words, but a well-crafted tweet can be worth a few hundred at least. On Monday, Stephen Smith asked, "Can someone explain to me how the hell an I-287/Tappan Zee BRT could cost ("as little as"!!) $1 billion?" With those few words, Stephen put his finger on a major weak point in the "enveloping BRT" strategy practiced by transit advocates. There is no "cheap" option for transit among the alternatives that were considered for the Tappan Zee corridor in the last round of discussions. Every transit option adds at least a billion dollars to the cost. When nobody can even find five billion for "just the bridge" (with a little stealth widening thrown in, naturally), it's too tempting for our austerity-obsessed "car guy" governor to cut the transit completely.
So why are the transit proposals so expensive, especially compared with the car proposals? The answer is a combination of four interconnected factors. First, all new busways are vulnerable to the dreaded "empty lanes" attack. Second, you're trying to serve a sprawling population with transit, which is always expensive. Third, the transit proposals all include some part of the "full corridor" from Suffern to Port Chester, while the current road proposal only covers the bridge. Fourth, transit advocates didn't have - and never have had, in this country - the political will to formally propose true dirt-cheap BRT.
The "empty lanes" attack has probably been attempted on every busway and HOV lane in history. In part it stems from basic physics: vehicles traveling slower can fit closer together safely, but faster ones have to leave more stopping distance between themselves and the vehicle in front. If the bridge managers succeed in speeding up bus traffic, the bus drivers need to leave more space. Drivers stuck in nearby traffic see that space and clamor for the lanes to be opened to them.
If demand for the bus or HOV lanes is at maximum (for example, the Lincoln Tunnel XBL with its steady stream of buses flowing down into the tunnel), drivers can't really say anything. But if it's anything less - say for instance that the project is just getting started - the clamor will start immediately and just keep building until the bureaucrats give in and open the lane to all vehicles.
Note that the bridge itself was pretty empty when it first opened - but there was nothing anybody could do about that. Tearing down the bridge wouldn't bring the money back. So they made the best of it. That's the double standard that all busways and HOV lanes face.
The transit agency could always run a bunch of buses whether anyone's riding or not, but that just opens them up to the related "empty buses" attack, another perennial favorite.
A strong political leader or movement could protect the busways and say "fuck you, it takes time to build ridership, we're not letting you drive in the lane." So a new busway has to have strong political sponsorship, or else it has to have a certain amount of ridership from day one.
It would add almost nothing to the cost of the current proposal - a rounding error - to build a new bridge with three general-purpose lanes and a busway in each direction. But if the busway is not immediately full of buses, car advocates will hit fast and hard with the "empty lanes" attack. I don't see any political leaders ready to stand behind a half-empty busway. The staff at Tri-State knows this well, and I'm pretty sure that's why they didn't object to the "BRT" actually being high occupancy/toll lanes on the bride itself. They don't want an actual busway on the bridge until they know it'll be full enough to stave off the empty lanes attack. So how do you build that ridership? That's where the other three factors come in.