It occurs to me that toll roads and transit may be natural political allies. If I build a toll road, I have a financial interest in being the best possible transportation alternative, and prefer if any alternative roads are more congested than my own, because that provides an incentive to pay for the use of my toll road.
Now, I can improve on my toll road if I charge variable tolls, in response to changing conditions. Because the cumulative effect of additional cars is greater with each additional car, I thereby need to charge more for each additional car.
Because of the Bureau of Public Roads congestion curve, we have a pretty good idea at lane efficiency, and thus of the rate to charge to represent the impact of an additional vehicle on all vehicles already on the roadway.
Ergo, both transit (with dedicated ROW) and toll roads have an incentive for alternatives to be congested, and thus a political/financial incentive to fight against expanded capacity.
Better yet if the toll road is privately owned, because private owners are immune to certain political pressures. I'm semi-perpetually kicking around the idea of a share-based system, with different landowners kicking in land for ROW and receiving shares in return, with the shares entitling them to revenue from the toll road... Now, if a transit agency were to buy into such an arrangement, providing capital for construction of the facilities, and receiving right of use for its vehicles in return, you could have a very interesting system.