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Air emissions from two- and three-wheelers: Initial issues assessment

This report is intended to present a summary of the current regulatory environment, provide appropriate background information, and introduce potential control measures for consideration in future policy development. It is expected that ICCT staff will prepare a subsequent and more focused report on policy development options that builds off of the material presented herein. Except where specifically noted, the term “motorcycle” is used generically throughout this report to describe both two-wheeled and three-wheeled motor vehicles. Three-wheeled vehicles are typically developed from two-wheel technology. Both utilize the same engine designs and have similar emissions issues. Thus the term “motorcycle” includes all equipment commonly referred to as mopeds, scooters, and motorcycles, as well as three-wheeled vehicles that are known locally by such names as autorickshaws (India and Sri Lanka), baby taxis (Bangladesh), mishuks (Bangladesh), tempos (Bangladesh, India, and Sri Lanka), and tuk-tuks (Thailand).

Motorcycles play important roles in fulfilling both personal and commercial transportation needs in most Asian and many southern European cities. The smaller physical size of motorcycles allows residents to navigate heavily congested areas in a reasonably efficient manner. Purchase and maintenance costs are also substantially lower than the corresponding costs for even small automobiles, making the types of low-cost motorcycles sold throughout most of Asia and Southern Europe a more economically efficient transportation option, especially for lower income residents. Asia accounts for almost 85 percent of new motorcycle sales, with Europe a distant second at about 8 percent. In recent years, there has been tremendous growth in motorcycle sales in Asia, with annual growth rates at or above 5 percent in most countries.

Asian markets reflect a pronounced bias toward small displacement engines of 125cc and less. This is in dramatic contrast to the distribution of motorcycles in the United States and northern Europe, where 500cc and larger engines dominate sales, and sales of small motorcycles are modest. Given the dominant role of Asia in the global motorcycle market, the bias found in Asian markets translates directly into a global bias for small motorcycles.

In light of the importance of smaller motorcycles in the global market, the emissions-related discussions presented in this report focus primarily on small displacement motorcycles (i.e., those with displacements of up to about 250cc). From both a design and cost standpoint, small displacement motorcycles present a more difficult emissions control target, so that the small motorcycle focus reflects a more challenging emissions control analysis.