Metro Transit Police say an increase in sex offenses in the past 18 months warrants the addition of rules that would allow the transit agency to ban passengers for up to a year.

Police Chief Ronald A. Pavlik Jr. will ask Metro board members Thursday to allow police to immediately suspend on a temporary basis anyone arrested on Metro property on suspicion of committing a sex offense or a crime involving a firearm. Police say such a rule would weed out repeat offenders and boost confidence in public transportation.

Pavlik wrote in his proposal to board members that suspects often are back on a train or bus — or at a rail station or bus stop — soon after an arrest.

“Suspects are placed under arrest and are typically released the same day and given a future court date,” he wrote. “Some of them are repeat offenders.”

The proposal comes less than two weeks after Metro’s inspector general’s office released a report saying transit police had no records showing they had investigated 1,200 reported crimes between 2010 and 2017, while 1,600 other case files were missing or withheld from the inspector general. Three reported felony sex offenses and 66 misdemeanor sex offenses were among the cases for which documentation was missing.

Representatives of the region’s congressional delegation and the D.C. Council said the findings were troubling and potentially damaging to Metro’s mission to boost ridership as the Washington region recovers from the coronavirus pandemic.

Under the proposed new rules, anyone caught allegedly committing a sex offense or crime involving a firearm or dangerous weapon would be banned for 14 days for a first offense, 30 days for a second offense and one year for a third offense. When arrested, suspects would receive “suspension citations” in writing that include the reason for the action, the length of the ban, the date the ban begins and a notice that violators would face criminal trespass charges.

Suspensions could be appealed within five days. Metro’s general counsel would appoint each case an appeals officer to review the appeal. The draft proposal does not say whether a ban would be lifted if charges are dropped or if a person is found not guilty. That and other details are expected to be discussed during the board’s meeting Thursday.

“This proposal is about keeping our customers safe and assuring we have every tool possible to prevent sexual offenses and dangerous acts,” Metro General Manager Paul J. Wiedefeld said in a statement Tuesday. “Everyone has the right to be and feel safe riding Metro.”

The proposal would permit exceptions from suspensions, allowing for transit travel under certain conditions. As an example, Pavlik said, a child or teenager who faces a ban could be allowed to travel with a parent or guardian.

SmarTrip credits that expire during a ban would not be restored under the proposal.

Other transit agencies, including the Los Angeles County Metropolitan Transportation, Bay Area Rapid Transit, the Chicago Transit Authority, Dallas Area Rapid Transit and the Metropolitan Atlanta Rapid Transit Authority — on which Metro’s proposal is modeled — suspend or ban people accused of crimes, according to Metro. Sanctions range from warnings to permanent bans for repeat offenders.

The proposal comes as the transit police department is undergoing internal change.

The agency’s police union is working with Pavlik to transform the department’s performance and job-evaluation standards, hiring practices and policing strategies after union officials agreed with many Black residents and D.C. Council members that officers were under pressure to reach arrest quotas and too often detained passengers for unnecessary questioning. In 2018, the D.C. Council decriminalized fare evasion in the city, partly because of those claims.

Fare evasion is still a crime in Maryland and Virginia, but Pavlik said riders caught skipping fares will not face the proposed suspensions.

According to Metro records, 89 incidents of indecent exposure were reported to transit police from January through the end of June, more than double the number during the same period in 2019. In 2020, 149 cases of indecent exposure were reported — 11 more than in all of 2019, despite a significant drop in ridership because of the coronavirus pandemic.

No rapes were reported on Metro property this year through the end of June, compared with two during the same period last year, according to Metro crime records. Aggravated assaults were up while larcenies and robberies were down.

Crimes not classified as felonies, such as indecent exposure, were down by more than 250 incidents through June compared with the same time last year. But Jeff Delinski, a former deputy chief of patrol operations at Metro who retired in 2014, attributed much of the decline to a drop in fare evasion citations in Maryland and Virginia, which fell by nearly 1,100 between 2020 and 2021, according to records.

Delinski said sexual harassment, indecent exposure and other misdemeanor sex crimes are difficult to investigate because the transit system allows perpetrators to move quickly and witness descriptions can be vague.

He said banning offenders would reduce repeat occurrences but wondered how Metro could enforce passenger bans other than blocking a SmarTrip account. Still, he said he supports the measure because it could restore confidence while the agency is seeking to rebound as the pandemic recedes.

“It is frustrating that there is a high rate of recidivism,” said Delinski, who is now director for the College of Professional Studies, Police and Security Studies program at George Washington University. “You oftentimes catch people for violations of the law, and they’re released very quickly and they’re back in the system using the transportation system.”