If Lightfoot forges ahead with congestion pricing in Chicago, what form should it take?

After coming clean about Chicago’s $838 million shortfall, Mayor Lori Lightfoot talked about “exploring revenue options to address rampant congestion that solves the problems of traffic, pollution … while simultaneously bringing in a fair source of funding.”

But what exactly would or should a Chicago congestion fee look like? Would it follow the leaders by drawing a ring around the downtown area and slapping a uniform, hefty fee on every vehicle entering the zone?

Or would the fee vary, as Chicago transportation experts have suggested, based on vehicle type, location, time of day, number of passengers and their ability to pay?

Those are just some questions Lightfoot must answer as she dips her toe into the brave new world of congestion pricing 44 years after Singapore blazed the trail.

There are no easy answers. None of it can happen without years of study, politically volatile debate and substantial spending on surveillance cameras, sensors and transponders.

“Congestion pricing means different things in different cities. We don’t know what’s best for Chicago yet. That’s why we’re asking the city to analyze the different options,” said Kyle Whitehead, a spokesman for the Active Transportation Alliance.

Brooks Rainwater, director of the Center for City Solutions from the National League of Cities, called congestion pricing a “valuable tool in the tool box” — but only for cities with “robust transportation systems that are able to move people out of personally-owned automobiles.”

“It accomplishes incredible reductions in overall vehicles on the road while you’re able to find additional support for public transit within the city,” Rainwater said.

He cautioned, however, that “a robust education campaign” is needed so people paying the fee know where the money is going.

“If you’re utilizing the dollars from a congestion pricing scheme to support existing public transportation system, the end result will be a net positive for everybody,” Rainwater said.

Singapore invested $110 million to implement the world’s first congestion pricing system in 1975.

According to a recent National League of Cities study, variable rates as high as $3 depending on time of day, road type and traffic conditions are imposed Monday through Saturday between 7 a.m. and 8 p.m. Inner-city traffic has declined by 24 percent, even with “massive population growth,” the study said.

In 2003, London jumped in. Its fee started at $6.15-per-vehicle and grew to $14.14 by 2014. It raised $3.9 billion in that first decade. Traffic congestion dropped by 30 percent in the first year alone. But it required an initial investment of $214 million.

Four years later, Stockholm spent $236.7 million to launch its “variable pricing” system. The investment was recouped in four years. Traffic volumes declined by 22 percent, and travel times during afternoon and evening rush were cut in half.

The maximum daily fee is $11.30. There is no charge on weekends, public holidays, the day before holidays, during evening and overnight hours, and during the entire month of July.

In 2021, New York City is poised to become the first U.S. city to try congestion pricing.

There’s talk of weekday rates of $25.34 for trucks and $11.52 for cars to raise anywhere from $780 million to $1.4 billion a year.

Details are still being sorted amid demands for exemptions. New Jersey congressional members complain congestion pricing is a “double tax” on New Jersey motorists already paying hefty tolls on bridges leading into Manhattan.

Rich Hein/Sun-Times

That is the political minefield Lightfoot is stepping into.

If she wants a quick fix for the $838 million shortfall she inherited, the best the mayor could hope for is to slap a higher, more equitable tax on ride-hailing vehicles now clogging Chicago streets.

The 72-cent flat fee on each ride booked on Uber, Lyft and Via “does not fully support the goals of equity and reducing congestion and green-house emissions,” transportation experts from the Metropolitan Planning Council and seven other groups wrote in a June 27 letter to Lightfoot.

Planning Council President Mary Sue Barrett, for one, wants the mayor to steer clear of a London model that she claims is “very dated thinking” and “doesn’t match Chicago’s reality.”

“It’s really complicated. You can’t just slap a circle around a city and say, ‘Everyone here is doing something good, and everyone here should be penalized,’” Barrett said.

One alternative is a higher fee on solo trips.

“If you’re the only passenger in [a private vehicle or] that Uber or Lyft, you would pay a supplemental fee. That’s where the congestion pricing conversation has evolved to. It’s much more responsive and incentive based.”

Rainwater said it makes sense for Chicago to “get this right” before autonomous vehicles hit the streets, drop people off and “ghost through the city waiting for another ride.”

“If you think about pricing the streets beforehand, you could make it so that’s not the direction these vehicles go. Instead, they might have to park somewhere outside of the city and only come in when people are actually calling for them, rather than a constant churn,” he said.