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Explaining the decoupling of freight traffic growth and economic growth. Ole Kveiborg og Mogens Fosgerau Danish Transport Research Institute. This presentation. Background Method Results Can the analysed factors explain the decoupling? Conclusions. Background.
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Explaining the decoupling of freight traffic growth and economic growth Ole Kveiborg og Mogens Fosgerau Danish Transport Research Institute
This presentation • Background • Method • Results • Can the analysed factors explain the decoupling? • Conclusions
Background • A model to forecast freight transport • Detailed data on production and transport • Data analysis • Freight transport follow same trend as economic trend • Freight traffic does not follow same trend as economic trend • Develop a model that can tell something about the historical findings
Historical development Production
The model ProductionDKK by sector Transport ton by commodity Handle factor Cmdt mix Distribution Production DKK by commodity Transport ton by commodity, veh.size, owner Value density Avg. load Avg. length Production ton by commodity Transport vkm by commodity, veh.size, owner
Model • The veh. km can be coupled to economic activity via the factors • Important: The model is an identity • What are the contributions from each factor? • Decomposition
Decomposition • Changes in traffic and transport explained by changes in factors • Calculate growth rates: • ”How much a variable grows related to its size”
Decomposition • Use this to calculate: The growth rate in veh. km equals the sum of the growth rates in the factors The impact is weighed by the relative share of veh. km.
Why decoupling? • Only traffic (veh. km) has been decoupled. Transport (tonkm) continues to grow with economic growth • Higher capacity utilization • larger trucks • (Less empty running) • However, • trips are getting longer • more goods are conveyed • Decoupling started in 1989/90 • Lasted for 5 years (primarily) • Average trip length • Handling factor
Conclusion • The decomposition methodology suitable to give insight in explanations for developments • The level of detail is quite aggregate • An indicator of which factors should be investigated further • Commodity mix does not contribute with more than sectors • Value to weight ratios perhaps not so important • Handling factor very important • How transport is performed important Fosgerau and Kveiborg (International Journal of Transport Economics 2004)
Conclusion • The analysis emphasizes the importance of knowing all underlying factors w.r.t. forecasting • Some elements increase transport and some decrease transport • Vehicle size an important explanatory factor for lower traffic growth • At some point vehicles within catagories cannot become larger and utilization reaches maximum • Then average trip length will, and veh. km will growth faster