appendix a - Velocidade

Executive Summary
2
The effect of speed on noise, vibration and emissions
from vehicles
May 1998
This report is Working Paper 1.2.1 for the MASTER project. This document provides
information on the relationships between vehicle speed and:
1) exhaust emissions and
2) noise and vibration
for roads of different types taking into account the effects of areas of transition of speed and
the effects of various speed management measures that may be applied. The effects are
considered in relation to changes to the vehicle fleet as the proportion of vehicles equipped
with catalysts changes.
This document also provides an overview of a variety of emissions models available which
may be suitable for incorporating in the MASTER framework. The report aims to provide a
qualitative overview rather than an account of quantitative performance of models. It also
provides a reference source for those using the MASTER framework to obtain the most
appropriate models/components for assessing the effects of speed management policies for
specific cases/locations. Some example data for basic cases are given in appendices.
The review of environment impacts of speed management systems indicates that the
following five factors need to be taken into account when assessing the impacts of speed
management strategies.
• The environmental impacts in terms of noise and emissions of speed management are not
straight forward.
• Changes in speed have different effects on different pollutants.
• Speed management measures may increase or decrease noise levels depending on specific
circumstances.
• Speed management measures may increase some pollutant emissions.
• Measures that induce acceleration and braking events (through either physical
intervention or through changes in behaviour) within the traffic stream will increase some
pollutant emissions.
In some circumstances the changes in speed during a journey may produce more pollutants
than the rest of the journey. This implies that the driving style may be as important as the
overall speed in terms of the environmental impacts. Further information is needed on the
effects of speed management strategies on driver behaviour, particularly in terms of
frequency and levels of speed changes.
The emissions from vehicles may not map directly onto local air quality. Dispersion models
will be required to predict pollutant concentrations at specific locations.