Changing San Francisco’s corporate shuttle bus system from one with shared stops scattered across the city to one employing a smaller collection of hubs would drive thousands of tech commuters into their cars and choke streets and freeways, a report concludes.

The Municipal Transportation Agency board will discuss the report at its meeting Tuesday, when a status report on the existing shuttle program will also be discussed.

The current shuttle system has come under fire from residents, who complain the buses clog city streets, and activists, who say the buses enable higher-paid workers to live in the city, resulting in increased housing prices and a rise in evictions.

Under the program, the corporate shuttle buses, which haul about 8,200 workers between San Francisco and jobs at tech and biotech firms on the Peninsula and in Silicon Valley, are allowed to stop at 125 locations and are restricted to larger streets.

The report on alternative systems was released Friday. The agency, and the San Francisco County Transportation Authority, looked at four scenarios for a hub system that would limit the large, sleek shuttle buses to a relative handful of stops for passengers.

The study considered plans for a single hub, a system of five hubs situated near BART, nine hubs close to freeways, and one employing 17 stops along a collection of designated routes.

All of those options would cause a steep drop in shuttle ridership — from 20 percent to 45 percent, the study found. About 90 percent of the former shuttle riders would climb into their cars, leading to increased traffic on city streets as well as on freeways, particularly Highway 101.

Officials with the Bay Area Council, which represents the corporate shuttle providers in negotiations with the MTA, said the study predictably showed that making it tougher to catch a ride to work on the buses would lead to a decrease in ridership.

“The hub study was crystal clear,” said Adrian Covert, vice president of policy. “The more you concentrate shuttle service, the worse the consequences. If you’re going to be making it more difficult for people to use a transit system, people are going to stay away, and use their cars.”

Critics said they’d like to see the big tech corporations invest in public transportation improvements instead of private shuttle buses, and said they still want the city to investigate the impact the shuttles have on housing.

“Our studies have shown that evictions and rents have gone up in areas near tech bus stops,” said Erin McElroy of the Bay Area Anti-Eviction Mapping Project and a shuttle critic. “ It seems as if the city is subsidizing the lives of people who ride the luxury commuter shuttles at the expense of those who don’t.”

A single hub, located in downtown San Francisco, would lose the most riders, the study found — about 45 percent. All of the others, it estimated, would retain roughly 75 percent of their passengers.

With more traffic on the streets, the number of collisions would likely rise, but the number of conflicts between Muni buses and corporate shuttles would be reduced. Fewer buses would travel on the city’s quieter streets, but the hub plan would take away more parking spaces and require more enforcement, the study found.

A separate evaluation of the existing shuttle program concluded that the system is working as planned.

Michael Cabanatuan is a San Francisco Chronicle staff writer. Email: mcabanatuan@sfchronicle.com Twitter: @ctuan