§ Dr. A. Thompsonasked the Minister of Transport whether he will facilitate the work of the police in controlling black smoke emission from road vehicles by introducing legislation to permit the use of some form of smoke measuring instrument similar to those used in California and Durban, details of which have been sent to him by the hon. Member for Dunfermline Burghs.
§ Mr. Marples:So far as I am aware, no instrument which would materially assist roadside enforcement by the police of the law against excessive smoke has been developed in any country. I understand that the Ringelmann chart as used in California has little or no advantage for this particular purpose over simple observation, and I believe the system which exists in this country for dealing with vehicles detected on the road making smoke is no less effective than the system in Durban of requiring them to go to special testing stations.