Controlling emissions from in-use vehicles: the role of inspection and maintenance (I/M) programmes

Abstract

Inspection and maintenance (I/M) programmes are needed to ensure that the benefits of emission control technologies are not lost through poor maintenance and tampering with emission controls. An effective I/M programme can significantly reduce emissions from uncontrolled vehicles as well. I/M programs serve two purposes; first, they help identify vehicles in which maladjustments or other mechanical problems are causing high emissions; and secondly, they discourage tampering with emission control equipment, so that the emission controls continue to be effective over the useful life of the vehicle. Many jurisdictions in Europe, Japan, the US, and an increasing number of developing countries have established periodic inspection and maintenance programmes for light-duty cars and trucks. Some jurisdictions have extended these programmes to include heavy-duty trucks and, in a few cases, motorcycles. These are often supplemented by programmes that identify and cite polluting vehicles on the road. There are two main types of I/M programmes: centralised in which all inspections are done in high-volume test facilities operated by the government or by a private government contractor; and decentralised, in which both emissions testing and repairs are done in private garages. The decentralised arrangement is less effective because of opportunities for fraud and improper inspections. Centralised programmes operated by contractors generally yield the best results and are recommended for most developing countries. This paper presents a comparison of decentralised versus centralised I/M arrangements with respect to institutional requirements, manpower and training needs, test procedures and costs. Costs and benefits of I/M programmes are also discussed.