I am unable to find at Tor Project | Debian / Ubuntu (bridge setup tutorial) any mention of a bandwidth or traffic.
Bandwidth limits - Relay performance - Relays FAQ — Tor does not mention “bridge”.
Default /etc/tor/torrc contains bandwidth related lines, but talks about relay not a bridge. (and it should in case it is applicable to a bridge?)
Relay Search shows “Advertised Bandwidth“ which is higher than i can afford (couple of megabytes per second).