8.3.6. Self-propelled vehicles used for performing work in underground work sites shall:(a) if they are powered by an internal combustion diesel type engine, be equipped with an exhaust-gas cooling system making it possible to keep the gas at 83 °C, whatever the motor’s operating conditions may be;
(b) be equipped with position lights indicating their maximum width;
(c) not discharge into the air non-diluted exhaust gas containing over 0.25% carbon monoxide.