(a) Subject to the provisions of section 1023.1 of this Part, no vehicle shall be operated in excess of the speed limit as posted in or upon the bridge crossings, in tunnels between portals and at the approaches to the toll booths.

(b) In the tunnels between portals, the minimum speed limit shall be 10 miles per hour in the slow lane and 30 miles per hour in the fast lane, except as posted.

(c) Nothing herein contained shall be construed to apply to police and fire department vehicles, ambulances, and to Triborough Bridge and Tunnel Authority emergency vehicles.