New Carrollton, Md. ? The federal government Tuesday began screening rail passengers for explosives at a suburban station near Washington, D.C., to test technology aimed at halting train bombings.

Homeland Security officials said the 30-day pilot program would not lead to wide-scale screening of rail passengers but would determine whether checkpoints could be installed temporarily at stations that may be the target of a threat.

“If we had terrorist intelligence that they were targeting a subway station or area, you don’t want to close it down and might want to deploy screening like this,” Homeland Security Undersecretary Asa Hutchinson said. “We want to have this as a capability.”

He added, “We do not want to change the nature of mass transit.”

The pilot is taking place at a one-platform station in Maryland, about 10 miles from downtown Washington, where about 700 people a day board Amtrak and commuter trains linking Washington and Baltimore.

Passengers boarding the 33 trains from 5 a.m. to 10 a.m. and from 3 p.m. to 6 p.m. on weekdays enter a portal set up in a station corridor that fires a series of air jets at a person’s back and waist. The jets, which are slightly startling, blow particles from clothing, hair and exposed skin into an overhead detection system that looks for traces of explosive material.

Passengers stand in the portal for about 10 seconds, and if a red light signals the presence of explosives, they will be searched lightly by hand. Screeners from the Transportation Security Administration will run the checkpoint.

Passenger baggage goes through an X-ray machine that alerts an operator when possible explosive material is found. The pilot program involves one $500,000 X-ray machine, one $132,000 passenger portal and 11 screeners.

The TSA advised passengers who would undergo screening to allow an extra five minutes and cautioned them to wash their hands of fertilizer and other materials that may have explosive residue.

Hutchinson said the pilot will measure how long screening takes and “how much passengers will put up with.” It was announced last month, weeks after terrorist bombings on commuter trains in Madrid killed 191 people on March 11.

As the afternoon rush hour crowd grew at the New Carrollton station, so did security checkpoint lines. Three minutes before one train was scheduled to arrive, TSA officials let anxious commuters bypass the equipment and head up to the platform. “Our goal is not to make you miss your train,” TSA spokeswoman Chris Rhatigan said.