Metro plans to transform its bus fleet next year to allow passengers to enter from both doors, aiming to speed up the boarding process to decrease wait times and delays, transit officials said.

Riders currently board through the front door, where fare boxes are located. Transit officials said all-door boarding would allow passengers to climb aboard faster, making rear doors fully functional, as opposed to serving only as exits.

During most of 2020, Metro closed off front entrances and the first few seats of Metrobuses to protect bus operators from exposure to passengers and the coronavirus. The move forced the transit agency to abandon fare collection, contributing to historic revenue losses for the agency.

Metro said the addition of fare targets at rear entrances would allow it to continue collecting fares if confronted with another health emergency that threatens operators. The targets act like fare boxes that passengers tap with their SmarTrip cards or mobile-fare-equipped cellphones.

Unable to collect fares for much of fiscal year 2021 — which stretched from July 1, 2020, to June 30, 2021 — Metro took in $20.4 million in bus fares. The agency had projected to collect $117.8 million before the pandemic.

All-door boarding is the latest advancement in public transit fast-tracked out of necessity by the pandemic. Last year, Metro introduced mobile fare cards and touchless fare gates, in part to help passengers feel more secure knowing they did not need to stand in lines or crowds to reload their fare cards at kiosks or swipe their cards at fare gates.

Phil Posner, chair of Metro’s Accessibility Advisory Committee, told board members at a meeting this month that riders want rear-door boarding to continue.

It was “one of the things that was recommended by the community members to increase the speed of buses, since a lot of the speed is lost in boarding and exit,” he said.

According to the National Association of City Transportation Officials, the time it takes a bus stop to load and unload passengers, known as “dwell time,” constitutes up to a third of bus travel time.

“With conventional front-door-only boarding, buses are victims of their own success: The more riders there are, the slower buses get,” the association wrote in a research paper. “These delays add up, costing agencies and passengers millions of hours — and potentially billions of dollars — each year. Systems across North America are finding a better way, using better boarding and fare payment methods to reduce dwell times dramatically.”

Miami, Paris, Oslo, Copenhagen and Berlin are among cities that have adopted all-door boarding, the association said. The San Francisco Municipal Transportation Agency has been using all-door boarding since 2012, resulting in dwell times falling by 37 percent. According to a December 2014 report on its boarding system, San Francisco transportation officials said all-door boarding sped up average passenger entries and exits by about 1.5 seconds.

The rear-door fare targets Metro plans to install on its nearly 1,500 Metrobuses are one part of a fare-modernization program, Metro General Manager Paul J. Wiedefeld said. Besides creating mobile fare cards for Apple and Android phones, the transit system has been installing new fare gates at all of its 91 rail stations.

Wiedefeld said 20 percent of the system’s 125 station mezzanines have the new touch-free stainless steel fare gates in service, including at the Gallery Place-China­town and Braddock Road stations, and he said installation across the system should be completed next fall.

Besides fare targets, Wiedefeld said, fare boxes are also being replaced on all buses.

Raka Choudhury, Metro’s Bus Priority senior program manager, said installation should begin in the summer, with all-door boarding beginning later in the year.