Environmental Engineering Reference
In-Depth Information
considerable fuel savings from lower speeds. This scenario assumes a medium-intensity
application of this package - a 30 km/hr (20 mph) speed limit on all residential roads and
80 km/hr (50 mph) on the strategic road network in London. Effective speed limit and driving
style enforcement is also assumed; potentially this is assisted by ICT means, such as speed
delimiters.
PP10 long-distance travel substitution:
This package deals with long-distance travel substitu-
tion, say from short-haul air to rail, but considers the Greater London part of the journey only
(the part of the trip within the urban area boundary). The increase in long-distance travel
within the UK, particularly by short-haul air travel and air freight transport, causes particular
concern for CO2 emissions. The modal share of air transport is still very low, but growth
rates are much above those of all other modes. Also, air transport is operating with a type of
'extraterritorial' status, being exempted from taxes that in national contexts are charged to all
other modes. Long-range leisure travel and airborne freight transport are growing on the basis
of the present cost situation. As increasingly important economic structures are relying on
cheap air transport, attempts to internalise at least a part of the considerable externalities will
become increasingly difficult in future years. Some travellers are also becoming used to the
availability of inexpensive, short-haul flights. This growth is being driven by growth in real
income levels and in the globalisation of economies, at least until recently. Rail has the
potential to offer a serious alternative to air travel over distances of around 300-500 km,
particularly for High-Speed Rail (HSR). The considerable improvements brought by HSR on
a limited number of national and international routes, together with faster services on existing
infrastructure (e.g. with tilting technology and new signalling), technical harmonisation,
organisational cooperation and strongly improved conditions for competition. These changes
would mean that there is considerable potential for long-distance rail-air substitution (beyond
the current Eurostar service) and even co-operation with HSR serving air travel for longer
distance travel. This scenario assumes a medium intensity application of this package and the
CO2 reduction impacts remain small.
PP11 freight transport:
The freight sector has a major role to play in helping to reduce
transport sector CO2 emissions. McKinnon (2007) gives a good overview of the possibilities.
Load factors are particularly important in the freight sector - the use of average emission
factors in analysis can over-simplify the analysis. In terms of the prevailing trends at the UK
level, CO2 emissions from heavy goods vehicles (HGVs) account for the highest proportion
of freight emissions (79 per cent). They appear to have risen by over 5 per cent (1990-2005),
even though the data are a little uncertain. There is also rapid growth in distance travelled by
light goods vehicles (LGVs). Because of the difficulties in finding good quality data in this
sector, uncertainties remain as to the real nature of the trends. The current declining CO2
intensity per tonne-km for HGVs can be attributed to a combination of reduction in empty
running, net consolidation of loads and improved fuel efficiency. Aggregate emissions continue,
however, to rise over time.
McKinnon discusses a number of areas that may help reduce emissions in the freight sector,
including improving handling factors (number of links in the supply chain), reducing length
of haul, improving mode share, proportion of empty running, fuel efficiency and choice of
fuel/power source.These can be considered in terms of subsidiarity (local production
and knowledge transfer) and dematerialisation (miniaturisation, advanced logistics and
distribution networks, load matching and material consumption). All can lead to savings, some
substantial. This scenario assumes a high-intensity application of the package. CO2 reduction
