13Further provisions as to charging of tolls
(1)A toll order may contain provision exempting from liability for tolls such descriptions of traffic as may be specified in the order.
This does not affect the power of the person authorised by the order to charge tolls to grant such other exemptions from toll as he thinks fit.
(2)A toll order shall contain provision exempting from liability to pay any toll—
(a)a police vehicle, identifiable as such by writing or markings on it or otherwise by its appearance, if being used for police purposes;
(b)an ambulance as defined in section 4(2) of the [1971 c. 10.] Vehicles (Excise) Act 1971;
(c)a fire engine as so defined;
(d)a vehicle exempt from duty under that Act by virtue of—
section 4(1)(g) of that Act (invalid carriages),
section 4(1)(kb) of that Act (vehicles used for carriage of disabled persons by recognised bodies), or
section 7(2) of that Act (vehicles used by or for purposes of disabled person).
(3)A person authorised by a toll order to charge tolls may, subject to the provisions of the order—
(a)suspend the collection of tolls;
(b)enter into agreements under which persons compound in advance, on such terms as may be agreed, for the payment of tolls;
(c)charge different tolls according to—
(i)the distance travelled, or
(ii)the day, time of day, week, month or other period; and
(d)charge different tolls for different descriptions of traffic.
In the case of a concessionaire the powers mentioned above are exercisable subject to the provisions of the concession agreement.