First came e-bikes, then scooters. Now the District is adding mopeds to the mix of micromobility services available in the nation’s capital.

The motor-driven cycles are the latest entrant into the city’s app-based transportation market, and they probably won’t be the last this year. D.C. transportation officials say they’re open to testing whatever happens to be the next big thing in transportation technology.

Rocket skates? Hoverboards? Unicycles? Maybe.

For now, the District Department of Transportation is focused on luring two other modes to city streets this year: electric tricycles — trikes — and e-cargo bikes, which could facilitate the delivery of food or packages.

“There are other types of technologies that are out there, that are emerging, and we are looking very closely at,” said DDOT Director Jeff Marootian, whose agency regulates the services. “We want to give residents and visitors as many options as possible, so we will continue to expand the program as thoughtfully as we can.”

The city is finalizing an adaptive bicycles or tricycles program, Marootian said, that would give people with special needs or disabilities access to the shared transportation services.

Officials are looking at the experience of other cities where companies are renting tricycles designed not only with extra stability for users who may not be comfortable on two wheels but also with extra storage capacity for hauling things like groceries.

One opportunity, Marootian said, is to partner with a commercial delivery company interested in piloting electronic cargo bikes, which would be a more sustainable way of making deliveries and could help reduce truck traffic in such areas as downtown. UPS has been testing deliveries via electric cargo bikes in places such as Seattle and Pittsburgh.

The mopeds, which the city will allow as part of a four-month pilot program starting this month, follow the entry of motorized scooters and dockless bike-share systems within the past two years. They come as District lawmakers push for legislation to govern the popular new services that have created disruptions on sidewalks and streets and as DDOT pursues ways to ease tensions among all the road users.

But as the city looks to broaden micromobility services, critics say its efforts would be better spent expanding the existing services that many residents have come to depend on. The District hasn’t significantly increased the size of scooter and bike fleets allowed since it launched its permanent program, which promised operators the potential for regular growth. Companies say it limits them from meeting the high demand for their services. Some operators say scooter usage is higher than that of their shared bikes, with some scooters being used up to six times daily.

For others, the addition of mopeds means the potential for more devices cluttering city sidewalks and jostling for space on already crowded streets. DDOT has created a team whose job is to work with the service operators and facilitate the inclusion of the services in the overall transportation system.

“Scooters have already made a mess of our city,” said Steven Reichert, a personal fitness trainer in Washington who has been a vocal opponent of the devices and argues they create a hazard for pedestrians. “Adding more vehicles like mopeds and trikes will only add to the chaos on our sidewalks and make it more unsafe for pedestrians.”

City officials say there are no immediate plans to significantly grow or scale back the fleets. Marootian said the city prefers to allow the programs to grow organically to facilitate their use and lessen the number of car trips.

So far, officials say, anecdotal evidence shows that people are using e-scooters and e-bikes to make short trips that otherwise would be made by car, including ride-hailing services such as Uber and Lyft. The devices are also filling gaps in the transportation system, providing options where Metro or bus service is limited, connecting people to transit, jobs and neighborhoods, they say.

Eight companies are licensed to operate in the District and combined are deploying as many as 5,600 shared scooters and bikes. Bird, Bolt, Lime, Lyft, Skip, Spin and Razor operate scooters only. Jump, which is owned by Uber, operates e-bikes and scooters.

Two companies — Revel and Muving — have expressed interest in participating in the four-month moped pilot. Under the program, each participating company will be allowed to deploy up to 400 of the vehicles.

“We hope to be fortunate enough to be selected by DDOT so that we can introduce our shared electric mopeds to the whole District soon and provide a reliable and convenient way to help people get where they need to go,” said Frank Reig, chief executive and co-founder of Revel, which operates in the New York area.

Reichert, who works with the elderly and people with disabilities and has been documenting scooter misbehavior, said he had hoped the city would have set more rules before allowing new personal mobility devices onto the streets.

“DDOT has proven it isn’t able to control the existing scooter fleets, so it’s irresponsible for them to expand the program,” Reichert said. “There are few regulations, and even then DDOT can’t enforce those regulations. Riders routinely ignore rules against riding on downtown sidewalks. Children are riding scooters illegally. And riding double, often with a parent and child on the same scooter, is common. We need the D.C. Council to act with real regulations and enforcement, and we need it fast.”

Legislation that aims to address the myriad complaints about e-scooter operations is pending in the D.C. Council.

Under the pilot, companies will be required to register their mopeds with the Department of Motor Vehicles, as well as to ensure users wear helmets, Marootian said. City law requires drivers to wear helmets and have a valid driver’s license. Mopeds are not allowed on sidewalks, and drivers must follow all traffic and parking rules.

D.C. officials said companies that apply for the pilot could have their mopeds on city streets as early as this month, if they meet all the requirements.

The city also is beginning to address some of the issues that have arisen with the proliferation of e-scooters and e-bikes, chiefly sidewalk clutter and conflicts among road users. DDOT is creating curbside parking for scooters and bikes at locations where their use is high and plans to have designated parking at 15 locations by fall.

Meanwhile, officials say, they anticipate the moped services, which have proved popular in other cities, will give residents and visitors another convenient option for getting around.

“We wanted to give our residents and visitors the opportunity to experience them,” Marootian said.

Mopeds have not been without controversy, however, having already raised concerns about people riding them recklessly and without helmets. They are typically built to have a maximum speed of about 30 mph.

John Townsend, spokesman for AAA Mid-Atlantic, said the automobile club is concerned about the potential danger to riders and other road users, including pedestrians and cyclists. He said the experience elsewhere has shown that moped crashes — even at lower speeds — can result in broken bones, scrapes and bruises.

“Moped safety must come first and so must moped safety training,” Townsend said, noting that research shows a high share of moped riders are young. In the District, the minimum age for moped riders is 16.

“Given the age of most moped drivers, where is the call for a compulsory basic training program or course for moped riders in the District?” Townsend said.

In the District and most states, moped operators are required to follow the same traffic rules as other motor vehicle operators. D.C. officials say they have looked at safety and operational feedback from other cities that have them, including New York and Atlanta.

“Like any mode of transportation, it is important that users follow the law and the rules and the terms and conditions that the companies set,” Marootian said.

Revel, which operates about 1,000 e-mopeds throughout Brooklyn and Queens, says its service costs $1 to start a ride, plus 25 cents per minute after the first minute.

“The first minute is free to give riders a chance to get comfortable and put their helmet on,” a company spokesman said. The company charges a $19 one-time registration fee to verify the user’s driver’s license and driving record. A discount is available for qualifying low-income residents.

Marootian said all the services the city is embracing, including mopeds, are electric, which in part aims to reduce carbon emissions and create more sustainable options for people moving throughout the city.

“The technology is emerging on a daily basis, and we have a great opportunity here in the District to embrace it and to see what our residents and visitors prefer as modes of transportation,” he said.