INTRODUCTION
Italian leader in postal services and in mail delivery is a public utility with an extensive
presence throughout Italy, consisting in a network of about 14,000 post offices, over
46,000 postmen and over 40,000 vehicles. As concerns environment protection, it is
necessary to pursue the aim of reducing noise pollution; for this purpose, limit values for
sound level must be respected; subsequent reductions in limit values and changes in
testing procedure may be decided on the basis of available technological potential and
analysis of cost/benefit ratios, in order to permit production of vehicles able to meet more
stringent limits.

Present paper gives a contribution to noise control, showing results of a comparison
between a traditional two wheel motorcycle and an electric four wheel motor vehicle, as
concerns acoustic performance. Sound pressure level and SEL produced by tested
vehicles, belonging to mail delivery service, were measured in different test conditions
according to standards. The effects of road surface and slope, together with exhaust
system noise emissions, were particularly taken into account. Finally an assessment of
noise mitigation granted by electric motor was carried out.

STANDARD REFERENCES
Both two and four wheel vehicles under test already obtained certificates of component
type-approval regarding noise pollution and documents fitting free movement of vehicles
and free placing on market of components; however measurement procedure according to
standards was applied in the present study as a reference to assess acoustic
performance.

Directive 97/24/EC
Directive 97/24/EC [1]of the European Parliament and of the Council of 17 June 1997,
concerning certain components and characteristics of two or three-wheel motor vehicles,
applies to permissible sound level and exhaust systems too. Procedure governing the
granting of component type-approval in respect of permissible sound level was set out in
Directive 92/61/EEC. The Commission takes into account and assesses the costeffectiveness
of proportionate and reasonable measures for reducing pollutant and noise
emissions; Member States may make provision for tax incentives only for motor vehicles
conforming to air-pollution and noise-pollution measures.
Directive 97/24/EC describes measuring conditions and method for vehicle testing during
component type-approval. As concerns noise, tests are provided both for vehicles in
motion and for stationary vehicles.

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