Query about a real time project-Bus management system

Hi, I'm a techie. I have some doubts regarding a real time project that I'm working on. It's related to a bus management system. My doubt is regarding the selection of RFIDs, have already shortlisted an RFID reader for the project. What is actually the maximum range of a reader - in case of frequency, meter and type? I would like to know about passive fixed UHF readers. Also please note that I'm using a fairly ordinary dipole antenna.

EZ Pass (toll taking system in USA)

[auto.howstuffworks.com]

will read with overhead reader
perhaps 20 feet
-- with RFID box going at 55mph

Whats this got to do with Reprap or 3d printing

I dunno, I think it is either spam or very badly targeted question about coursework

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