The MTA has just released its most ambitious capital plan, at a jaw dropping $51.5 billion, and a huge chunk of that funding ($15 billion) is expected to come from congestion pricing. But the agency, which is in charge of the program, has thus far released no details about how it will implement the tolling on drivers.

On Tuesday the Regional Plan Association (RPA), a tri-state transportation-focused think tank that has been doling out advice to policymakers for 90 years, stepped into the breach with a comprehensive report on how to make congestion pricing work.

The report includes some suggestions on the fairest amount drivers should be expected to pay, based on calculations by energy-policy analyst Charles Komanoff and his souped-up spreadsheet.

The RPA suggests there could be a flat fee of $6.62, a price that could also go as high as $9.18 during the busiest time of the day and as low as $3.06 at night. It recommends truck drivers pay more than motorists in smaller cars.

And it suggests that any toll be a two-way toll, so there’s no incentive for drivers to find cheaper ways to get in or out of the zone. Under a one-way system, a driver could enter during the busiest time of day, but linger until the pricing drops rather than moving in and out of the area. The congestion pricing zone will extend from Lower Manhattan to 60th street, excluding drivers who stay on the FDR Drive and West Side Highway and don’t drive on side streets.

The MTA has released no details about its congestion pricing plans (or as it’s now known: Central Business District Tolling). It hasn’t even appointed the members of the Traffic Mobility Review Board, a group of six people, including a representative from Long Island, Hudson Valley, New York City chosen by the mayor, Bridges and Tunnels and a chairperson, which will set the fees and determine how exactly this will work.

“We appreciate RPA’s report and welcome their attention to and support for the effort to reduce congestion in the Manhattan Central Business District, while also raising money for MTA’s Capital Program,” an MTA spokesperson wrote in an email. “We look forward to discussing the program in more detail with them.”

arrow Possible congestion pricing numbers. Regional Plan Association

One recommendation that some lawmakers may find unpalatable is prohibiting exemptions, not even for emergency vehicles.

“The problem is that the more exemptions we carve out the more everyone else is going to have to pay,” Tom Wright, president of the Regional Plan Association, told Gothamist/WNYC. “Part of what we’re trying to do is make the system more fair across the board.”

Komanoff argues that giving 10 percent of drivers’ exemptions will result in a loss of billions in revenue and increased traffic, defeating the benefits.

The RPA says even if emergency vehicles get an exemption, the guidelines have to be very clear, otherwise, it could be easily abused. (See NYC’s placard abuse issues.)

The congestion pricing legislation, which passed the legislature and was signed by Governor Andrew Cuomo in April, gives vehicles carrying disabled people an exemption, and offers a tax credit to drivers who live in Manhattan and make less than $60,000 a year. New Jersey Governor Phil Murphy says he has a “conceptual understanding” with the governor that his residents won’t be charged to enter the zone if they were already charged crossing a tunnel or bridge. But Murphy has nothing in writing to this effect.

There is one group the RPA doesn't mind cutting some slack to: taxis and for hire vehicles. The RPA argues they’ve already been paying a congestion fee, and that it is sufficiently on track to raise $400 million a year. The RPA argues that these drivers need to enter the zone anyway and a higher charge might keep them away, so keeping the current surcharge of $2.50 to $2.75 in place is enough to keep them coming.

One of the biggest questions surrounding congestion pricing is how technically the money will be collected and how the system will know whether someone has entered the zone. The MTA received a proposal in August for a tolling infrastructure program, and expects to award a contract by the end of this year.

The RPA suggests the MTA avoid just going with E-Z Pass to collect tolls, even though it may be the simplest to implement. The RPA doesn’t have a specific type of technology in mind, but notes a more nuanced system could be more flexible and fair by charging drivers based on number of miles driven, for example.

The RPA says it has been fielding calls from Boston, Los Angeles and Chicago about what New York is doing.

"This is going to set the standard for the rest of the country,” said Tom Wright. “And I think that we have an opportunity and obligation to do it right here."