Editor’s note: This story has been updated to clarify the VTA’s interactions with organizations representing tech employers.

Tech companies aren’t just secretive about their future products. They’re also unwilling to share information about their shuttle buses.

After requests for company data in its effort to count corporate shuttles along Highway 85 did not yield results, the Santa Clara Valley Transportation Authority set up cameras to determine how many buses are on the road.

“The best we can do is spy on them in video cameras,” said Adam Burger, the transit agency’s senior transportation planner, at an advisory board meeting in Cupertino on Monday.

Tech shuttles have long been a controversial topic in San Francisco, where they’re blamed for clogging neighborhood streets and sending housing prices near stops skyrocketing. But companies like Google and Apple operate a network of buses throughout the Bay Area, picking up employees from points south and east of their headquarters, not just from the city.

The transportation agency is examining the impact of corporate bus fleets as part of a study that will analyze potential transit projects on Highway 85. One reason the buses are popular with workers is the lack of convenient connections from major rail lines like Caltrain and BART to corporate campuses. Facebook and Apple are each about 4 miles from the closest rail station.

The agency set up cameras on Nov. 14 and 15 in six locations in the region: Middlefield Road, El Camino Real, McClellan Road, Quito Road, Leigh Avenue and Blossom Hill Road. Finding out more information about the buses could help South Bay cities and the agency better determine how to improve traffic. Potential projects that could be explored include light rail, dedicated bus roads or even a bus-only lane that the tech shuttles could also use.

The agency estimates that companies spend roughly $249,000 a year to operate each shuttle, with an annual cost per rider of $12,000 to $15,000. At peak times, in the northbound direction, there were 111 shuttles on Highway 85 at El Camino Real in the morning and 130 buses in the evening, according to the agency’s study. At Middlefield Road, there were 97 shuttles northbound at peak times in the morning and 106 shuttles in the evening. Peak times were from 6 to 10 a.m. and 4 to 8 p.m. The study also noted that half of the shuttle trips during peak times had no passengers, as the buses deadheaded back to pick up more passengers.

“Using our limited roadway space more efficiently is a strategy that may be worth encouraging with a separated guideway that allows corporate shuttles,” said Holly Perez, the transportation authority’s public information officer.

The traffic on Highway 85 is getting worse, said Cupertino Councilman Barry Chang. While tech buses carry more passengers than individual cars, they are still using the roadway, said Chang.

“If the highway gets congested, everybody gets stuck on the highway,” he said.

The agency says it asked companies for shuttle bus data through the Silicon Valley Leadership Group and the Bay Area Council but did not receive it. The Silicon Valley Leadership Group declined to comment on why their members did not respond to the requests. Adrian Covert, the Bay Area Council’s vice president of public policy, acknowledged that his organization was contacted but said he had expected “more follow-up” by the agency. The council says it has cooperated with other agencies in such requests. Apple and Google, two of the region’s largest employers, are members of both organizations.

Chang said the firms may not want to the public to know how many employees work in each location, information that could be deduced from shuttle counts.

The initial phase of the Highway 85 study cost $400,000, including the tech bus data. It is unclear how the next phase of the study will be funded.