Tunnels for road and street traffic become increasingly important for
transport provisions, primarily in large cities. Currently, there are in
Stockholm and Gothenburg high-volume tunnels in the primary road network. In
addition, many new tunnels will soon be finalised or are planned both in
Stockholm and Gothenburg. The exhaust emissions in road tunnels may not
exceed certain limits. Road tunnels are equipped with ventilation systems to
make sure that limits for air quality are not exceeded, primarily emissions
of NO2. The ventilation systems are dimensioned using data on maximum
expected emissions per unit of time. VTI has obtained a commission from the
Swedish National Road Administration (SNRA) to develop a model for
calculation of exhaust emissions in tunnels, which in addition shall take
into account oversaturated conditions. Currently, SNRA has no satisfactory
model for calculations at hourly level. The objective of the development
effort has been to formulate a calculation model for travel speeds and
emissions in motorway tunnels, to be used when tunnel ventilation systems are
dimensioned. For a complete structure, the model shall provide individual
tunnel tube emission data for hourly traffic, split upon homogenous - from
the viewpoint of traffic engineering - road links and ventilation segments.
This report describes the results of the development project for calculation
of emissions in tunnels. The completed model comprises two parts, one for
calculation of speed and corresponding hourly flow at given demand level and
one for calculation of emissions, using hourly flows and speed as input data.
For each part, there is a computer program with user manual. Test runs of the
model for some basic typical tunnel cases, has been carried out to illustrate
the results of the total model. The total emissions of NOx (kg/km) as a
function of traffic flow have been calculated for different degree of traffic
load. In addition, the model has been validated by comparisons of calculated
NOx values from the model with measured NOx values in three different
tunnels: the Gnistäng tunnel and the Tingstad tunnel in Gothenburg and the
Southern Route tunnel in Stockholm.
Linköping: Statens väg- och transportforskningsinstitut., VTI meddelande 968 , 2004.
Swedish, Sweden, Tunnel, Emission, Model, Air pollution, Limit, Calculation, Speed, Traffic flow, Nitrogen oxide, Ventilation