The Collaborative International Dictionary of English v.0.48:

Pontage \Pon"tage\ (?; 48), n. [LL. pontagium, from L. pons,
   pontis, a bridge: cf. F. pontage.] (O. Eng. Law)
   A duty or tax paid for repairing bridges. --Ayliffe.
   [1913 Webster]

Bouvier's Law Dictionary, Revised 6th Ed (1856):

PONTAGE. A contribution towards the maintenance, rebuilding or repairs of a
bridge. The toll taken for this purpose also bears this name. Obsolete.