Boardman told a Senate panel Tuesday that the agency has expanded its use of explosive-sniffing dogs and is in close contact with U.S. and international security agencies.
He said promising ultrasonic and laser technologies may enable detection of track problems far ahead of trains. But he cautioned that trains are more vulnerable to attack than planes because terrorists have more ability to access trains and track.
He said more patrols of tracks are needed to identify specific points of vulnerability.
