A Lime-S scooter is parked on a sidewalk in Washington. (Luz Lazo/The Washingtonn Post)

The dockless bicycles and scooters that have popped up like mushrooms in the District over the past year will be allowed in Arlington County under a nine-month trial, with a handful of limits on the size of the fleets and where the vehicles are allowed.

Bird, a California-based dockless electric scooter company, already has 500 scooters in Arlington, and Lime, another scooter- and bike-sharing operation, plans to operate in the county.

While Arlington plans to limit each company to 350 devices at first, county officials noted that the District, Arlington and Alexandria are a single market, and that bikes and scooters that originate in other jurisdictions may end up in the county.

“Arlington was on the cutting edge of regional bike-share programs when we helped found Capital Bikeshare in 2010,” County Board Chair Katie Cristol (D) said. “We are awash in opinions of scooters . . . but this county does not react based on anecdotes but on data.”

The Arlington County Board voted unanimously Tuesday to start the trial on Oct. 1 and ban scooters from sidewalks and trails. No one younger than 16 will be allowed to rent them. Companies renting the dockless bikes, e-bikes and e-scooters will have to pay Arlington a one-time $8,000 fee for each category they offer and will have to agree to provide data on usage, trips and where the vehicles are parked. Arlington is also limiting the speed of scooters to 10 mph and bikes to 15 mph.

The District is running a similar pilot program until December, and Alexandria is likely to consider its own regulations in the next few months, Arlington transportation officials said.

Last week, the first death of a man riding an electric scooter was reported in the District. He died in a collision with an SUV. Nationwide, hospital emergency rooms are reporting a major spike in visits due to injuries from electric scooters. And Arlington residents complained Tuesday night that some riders abandon the dockless bikes and scooters on private property or block driveways and sidewalks. The county is accepting complaints and observations at mobility@arlingtonva.us.