Environmental Engineering Reference
In-Depth Information
As Table
2
values show, the road mode do-nothing alternative accounts for over
72.5 million tons of CO2. It can be seen how the mean increase in GHG emissions
due to the extension of the HCR network included in the PEIT accounts for near 2
million tons of CO2, which represents a 2.70% increase compared to both the do-
nothing alternative value for the road mode, and total road and rail emissions of the
do-nothing alternative. This comparison could be carried out if different road and/
or rail alternatives were assessed.
Regarding the rail mode; do-nothing alternative accounts for only 234,000 t. The
extension of the HSR network included in the PEIT accounts for nearly 170,000 t
of CO2, which represents over a 72% increase, in terms of the do-nothing alterna-
tive value for the rail mode, whereas it represents only a 0.23% increase of total
road and rail emissions of the do-nothing alternative.
The comparison of the absolute increases in GHG emissions between road and
rail modes (2 million vs. 170,000 t of CO2) gives us an idea of the significant
difference in the contribution of the above transport modes to GHG emissions,
which is obviously proportional to their corresponding traffic volumes.
Conclusions
This paper defines a methodology for the assessment of climate change effects of
transport infrastructure plans, based on the calculation of GHG emissions. The meth-
odology has proven its efficacy in deriving GHG emissions via the calculation of an
accessibility indicator, and the resulting induced travel demand that stems from travel
time savings. This approach could be of valuable use in cases when a calibrated transport
demand model is not available, which is frequently the case at strategic levels.
The application of the methodology has also highlighted the significant differ-
ences in the contribution to GHG emissions of road and rail modes, given the severe
unbalance in modal split. A modal shift towards rail mode would result in important
reductions in GHG emissions, along with other environmental benefits of more
balanced modal shares.
Accompanying measures are needed in order to encourage a modal shift from
road to rail, in order to take full advantage of network accessibility improvements
derived from infrastructure investments. Improvements in punctuality, reliability,
perceived comfort and higher frequencies are some of the possible measures that
may be effective for this purpose.
In this sense, the integration of road and rail modes in order to measure modal
shifts is on our research agenda. Finally, other future research directions we are
exploring refer to the application of the methodology to a set of road and rail alter-
natives, in order to assess the sensitivity of the results to different variables, such as
rail commercial speed.
Acknowledgments
The results included in this paper are part of the project “Assessment of the
effects of transport infrastructure plans, on mobility, the territory and the environment”, financed
