Union representatives and safety consultants say the case of the man charged with attempting to assassinate President Donald Trump at a media dinner is the latest example of someone allegedly trying to use the country's passenger trains to smuggle guns for an attack. And they say it won't be the last time until ground transportation companies address security and passenger screening at the vast network of stations. Rail passenger advocates argue that TSA-style checkpoints are impractical at both rural stations and bustling hubs of commuter traffic with many entrances and exits.