What is the fine-grained topic of the following text: TxDOT Information Officer Andrew Carlson said the delay comes as part of a redesign of the railroad bridge after it was originally designed to have a 16 ½ feet clearance, but with recent changes to TxDOT policies it must now have an 18 ½ feet clearance. Only return the topic.
Redesign delay of a railroad bridge due to clearance policy changes in TxDOT