Whilst some transport modes are more harmful to the environment than others, we need to understand the commercial and logistical considerations for their selection by businesses and other organizations.
SOuRCE Based on Defra (2011).
Figure 3.1 CO2e emissions by transport mode
0 200 400 600 800 1000 1200 1400 1600 1800
Air
(short-haul) Air
(long-haul) Van HGV Rail Sea
gCO2e per tkm
Operational factors
External factors affect the choice of transport mode. The availability and quality of infrastructure differ between countries and transport modes, as does the availability and quality of vehicles and logistics service provid- ers. In addition, local law, regulations towards transport and the price for transport will impact the choice, with many developed countries trying to encourage transport modes of lower emission impact, for example through fuel taxation, aviation tax in the UK, or tax reductions for environmentally friendlier vehicles. Local climate becomes an issue when, for example, rainy seasons affect some transport modes more than others.
The availability of infrastructure needs to be seen in connection to the location where the goods need to be delivered. Accessibility by water or rail determines whether these modes can be considered as options in the choice of transport. Sea and rail transport very often need some road transport for the final leg of the journey.
Cost and service requirements
Customer requirements towards cost and service impact the selection of transport mode. Larger order sizes and longer order cycles make the use of less flexible transport modes worth consideration. An example would be a product such as white undershirts, which are a common low-value item sold in larger quantities and not subject to fashion changes. They would usually be shipped in sea freight containers from the Far East to markets in Europe or North America, as shipping by sea is a rather cheap way of transporting these large, low-value quantities.
Drivers for the growth of road freight transport in the past were the logistics strategies of ‘just-in-time’ (JIT) manufacturing, ‘efficient consumer response’ (ECR) in retailing and a trend towards centralization of operations and warehousing. JIT reduces inventory holding by having items delivered to an assembly line when they are needed, thus avoiding storage and inven- tory holding. Deliveries will therefore be optimized from an assembly line perspective, with sometimes short notice periods. This usually results in more frequent but smaller orders and transport, requiring flexibility that can usually only be provided by road transport. ECR is a common strategy in grocery retailing, and requires high levels of flexibility and responsive- ness. It aims to replenish quickly what customers have bought at the store.
Customer demand can be volatile and ECR uses a high frequency of store deliveries in response to this volatility. This way it increases the number of journeys and the proportion of less-than-truckload deliveries.
Freight Transport 71
Product characteristics
The value density and weight density of transported items as influenc- ing factors towards the choice of the transport mode have already been mentioned, but other product characteristics can also influence this choice.
Perishable products will put a focus on speed of delivery if their ripening cannot be delayed. Bananas exported to western markets, for example, are harvested unripe and then transported in temperature-controlled ships to the destination countries. The same, however, is not possible for fresh flow- ers, which therefore have to be transported by aeroplane. The transport of hazardous goods is usually regulated, affecting the speed of delivery and the choice of transportation mode to protect the public from potentially harm- ful accidents.
Consignment factors
Whether a consignment can actually fill the size of a standardized unit of transportation has a significant impact on the price for freight transport.
The loading factor (or utilization) for a transport mode, however, will be important for the environmental assessment. Whether the vehicle returns empty or other goods can be hauled back changes the calculation tremen- dously. Loads may also be incorporated into an already planned trip or may contribute to the utilization of an existent system, which may be finan- cially and environmentally more attractive than setting up the use of a new system. For example, much air freight arrives on passenger planes, which would be serving a route anyway to transport passengers. The allocation of emissions for freight transport on a passenger plane is difficult, as the flight would have been scheduled anyway.
The carbon emissions of transport modes depend on the type of fuel and engine that is used. Electrified transport modes – using electricity generated at a power station – such as the train services in many Continental European countries have lower carbon intensity than those transport modes run on fossil fuels.
Although sea transport is relatively low in energy intensity per tonne-km, the bunker fuel burnt by ocean vessels is considered as being particularly pollutant and can therefore lead to the concentration of emissions and to respiratory health problems in port cities. One way of reducing the environ- mental impact on port communities is therefore to supply ships with energy from the grid whilst they are in port or to enforce a change in the fuel that is being used. The Baltic Sea region is an example of a shift to less polluting ship fuel.
The emissions from individual fuel types differ hugely between various pollutants. To make the discussion more transparent and measures compa- rable, the guidelines for company greenhouse gas reporting use CO2e – CO2 equivalence – as a measure. The figures from this guideline are to be used to estimate the environmental impact of a company’s logistics activities in the lifecycle assessment of a supply chain.
The figures in Table 3.1 above were calculated based on average loading factors in the UK. The figures for air freight also considered the proportions of freight on passenger planes and on pure freight aircraft. This means, however, that the numbers are averaged across the entire country and individual perfor- mances may differ strongly. The guidelines are therefore quite detailed and they provide numbers based on different fuel types, vessel size, vehicle type, etc.
Additional complexity to the discussion is added by a report from PE International (2010) arguing that water and rail are not always greener than road freight transport. The study compares road and rail modes in several scenarios with various assumptions. When the comparison includes all factors like emissions from producing electricity and diesel, loading factors, type of goods to be transported, length of train, proportion of the journey from factory to freight terminals etc, it can in some scenarios show lower emissions for the lorry. In one scenario of light goods, river barge transport even has the highest emissions of all three compared modes. Since the study was conducted in Germany, comparisons in future also need to consider the reduction of nuclear energy in the electricity mix. If nuclear energy is replaced with energy from coal or other highly polluting ways of energy production, the environmental performance of electricity-powered trains will decrease.
Table 3.1 Comparison of greenhouse gas emissions by transport mode gCO2e per tkm
CO2 CH4 N2O Total
Van 537.0 0.16 3.71 540.9
HGV 127.2 0.4 1.91 129.2
Rail 28.5 0.05 3.06 31.6
Sea (general cargo, 100+ TEU)
11.0 0.00 0.08 11.1
Air (long-haul) 610 0.00 10 610
Air (short-haul) 1740 0.00 20 1760
SOuRCE Defra (2011).
Freight Transport 73 Options to reduce the environmental impact of transport operations are to reduce the emissions from the current mode of transport, shifting freight towards less polluting modes of transport, and the overall reduction of freight transport. These options are now discussed in more detail.