This double Q & A in City Hall News with Transportation Commissioner Janette Sadik-Khan and City Council Transportation Committee chair James Vacca has a lot of revealing moments.

There’s Vacca’s desire for better cross-Bronx bus service, combined with his assessment that the MTA will have to “do more with less” and his observation that “I don’t sense at this point in time that there is a groundswell of support” for either congestion pricing or bridge tolls. Add it all together, and it paints a bleak picture: The transit system is inadequate, it’s going to have even less funding to work with, and even though we know we can do something about it, political leaders are going to sit on their hands because there’s no “groundswell of support” for the solutions.

Then there’s the question, “Have new bike lanes and pedestrian plazas won over New Yorkers, or are they seen as a temporary fad?” Sadik-Khan reached right for the numbers: 56 percent public approval for bike lanes, 40 percent improvement in pedestrian safety on streets with bike lanes, 50 percent reduction in injuries to all users on streets with protected bike lanes.

Vacca reached for outdated theories about traffic, unsupported assumptions about bike lanes, and an abiding belief that car parking is essential for commerce:

I do think the question people have to ask when they have a pedestrian-plaza proposal, and it’s a fair question: If you omit traffic here, where does traffic go, and what is the impact of the diversion on those surrounding streets? Is there a need for more pedestrian-friendly streets in this city?…On the bike lanes I think you have to look on a case-by-case basis. Perhaps in some communities, bike lanes have had a positive impact, and in other communities, we hear the bike lanes are not used. And why are there bike lanes that are not used omitting lanes of parking that could be available for the small-business community or commercial tenants? I think on bike lanes, neighborhood input becomes very important.

Does anyone who thinks seriously about transportation still believe that traffic flows like a river? That diverting it from one place will cause it to shift someplace else? There are piles of empirical studies showing this is not the case.

In addition to the classic NYC example of the vanishing traffic that followed the collapse of the old Miller Highway, we now have much more recent proof from Times Square. Data from millions of taxi trips shows that travel times improved after the Midtown plazas were implemented. As much as skeptics would like to pretend that data doesn’t exist, it is powerful evidence that traffic is not a force of nature.

And where are these unused bike lanes obliterating rows of parking? Do they exist in the real world? The new bike lanes that are generating big growth in the number of cyclists are protected by rows of parked cars.

I can think of one recent bike project that eliminated a parking lane — the Flushing Avenue bike lane near the Brooklyn Navy Yard. The city in fact chose this configuration in response to neighborhood input — the businesses in the Navy Yard said they had no problem with the conversion of parking lanes to bike lanes. I invite Vacca to come on down to Flushing Avenue any morning and join the swarms of cyclists who ride it every day.