BY SCOTT SHENK

After last year's deadly Sky Express bus crash in Caroline County, there were calls for, and promises of, better enforcement and safety regulations on the interstate bus industry.

The primary focus was on "curbside" bus companies that skirt the rules, causing dangerous situations like the Sky Express crash in which four died.

In the past year, enforcement has been ramped up, as seen by last week's multi-state roundup of alleged rogue bus companies. But proposed regulatory and safety laws continue to languish amid congressional budget battles.

"I think a lot of things have happened," said Peter Pantuso, president and CEO of the American Bus Association. "I think the [Federal Motor Carrier Safety Administration] has learned a lot from the Sky Express accident."

Still, he added, plenty more needs to be done.

Curbside bus companies make up a small percentage of the interstate bus industry. Most bus companies work out of terminals. The curbside companies have cheaper fares and no central location. Instead, they pick up passengers at designated places along interstate highways.

According to an October 2011 study by the National Transportation Safety Board, the agency reported that only 71 of 4,172 bus companies are the curbside variety.

But, the report stated, the fatal crash rate is much higher for those discount bus companies.

Pantuso said they're "a small piece, but it's a piece that gives the industry a bad name."

The Sky Express crash happened shortly before 5 a.m. on May 31, 2011.

The bus left Greensboro, N.C., the previous night and was headed for Chinatown in New York City, but ran off Interstate 95 in Caroline County, hit an embankment and overturned, killing four women and injuring another 53 people.

The driver, Kin Yiu Cheung, 38, has said that he fell asleep. He and a Sky Express dispatcher, 41-year-old Zhao Jian Chen, each face four counts of manslaughter. Chen is accused of forcing Cheung to work after the driver reportedly said he was too tired.

Sky Express epitomized the problems with the curbside bus companies, which authorities have a difficult time tracking.