Japan's super-sleek locomotives that dart across the island nation at breakneck speeds have earned the nickname "bullet train." Closer to home, if Maryland's commuter rail system doesn't pick up its pace, it may be dubbed the "slug train."

To the chagrin of daily commuters, for the past few months MARC trains on the Penn Line - a route that snakes through Anne Arundel County with stops in Odenton and BWI Thurgood Marshall Airport - have been late and canceled more than usual, especially during rush hour, Maryland Transportation Administration data shows.

"All I want is to see my train arrive on time, every day," said Patrick...