A survey conducted by distributing a form postcard to travelers or by mailing such a postcard to the home, with a request that the card be completed and mailed back. (TRB)
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POSTED SPEED
Maximum allowable speed over a section of track by fixed or temporary signals and rules.
POSTMARK
A printed, stamped, or otherwise placed impression (exclusive of a postage meter impression) that is readily identifiable without further action as having been supplied and affixed on the date of mailing by employees of the U.S. Postal Service.