Environmental Engineering Reference
In-Depth Information
2.22 Air Quality Models Sensitivity to On-Road Traffic
Speed Representation: Effects on Air Quality
of 80 km h
−
1
Speed Limit in the Barcelona
Metropolitan Area
José M. Baldasano
1,2
, Pedro Jiménez-Guerrero
2
, Eugeni López
2
,
María Gonçalves
1
, and Albert Soret
2
1
Environmental Modelling Laboratory, Technical University of Catalonia. Avda. Diagonal
647, Edificio H, Oficina 10.23, 08028 Barcelona, Spain
2
Barcelona Supercomputing Center - Centro Nacional de Supercomputación (BSC-CNS).
Earth Sciences Department. Jordi Girona 29, Edificio Nexus II, 08034 Barcelona, Spain
Abstract
This work explores the changes in urban air quality caused by the intro-
duction of a maximum speed limit to 80 km h
−1
on motorways in the Barcelona
Metropolitan Area. The tool used is the WRF-ARW/HERMES/CMAQ modelling
system. Simulations take into account the entire year 2008 versus the traffic con-
ditions for the year 2007. This speed limitation has been implemented in the
HERMES emissions model, which considers hourly variable speeds and hourly
traffic intensity in the affected area, taken from measurement campaigns for the
aforementioned years; it also permits to take into account the traffic congestion
effect. Overall, for the whole metropolitan area, the emissions are reduced up to
4%; however the local effects of this reduction achieve an important impact for
specific points of the domain under study, reaching 11%. In this sense, the speed
limitation effects assessed represent improvements in air quality levels (5-7%) of
primary pollutants over the area affected. Hence, limiting the circulation speed to
80 km h
−1
has been proved as a feasible traffic management strategy for air quality
improvement in urban areas.
1. Introduction
Improving air quality in urban areas is nowadays an important environmental
challenge (Baldasano et al., 2003). The public administrations are testing manage-
ment strategies mainly addressed to reduce on road traffic emissions, because this
sector is the largest contributor to anthropogenic pollutants emissions in the urban
environments (Colvile et al., 2001; Querol et al., 2001; Ghose et al., 2004; Nagl
et al., 2006). A way of reducing traffic emissions consists in changing the speed
circulation patterns. The speed dependency of emissions varies as a function of the
pollutant, depending on the vehicle age, weight and cubic capacity of the engine.
