Senators are getting trapped in a subway built exclusively for their convenience, leading to calls for more funding and some amusement for those who opt to walk the Senate’s tunnels instead.

Riding the tiny, three-car train, which shuttles between the U.S. Capitol and two Senate office buildings, has become a gamble for senators, staffers, and congressional reporters alike. It was constructed to cut down on walking time, and when operating smoothly can travel from end to end in under two minutes. But the train’s automated system, brought online in the 1990s, also stops abruptly and can leave riders briefly stranded on the tracks.