Contents lists available at ScienceDirect Transportation Research Part D journal homepage: www.elsevier.com/locate/trd Does urbanization lead to less energy use on road transport? Evidence from municipalities in Norway Yongping Liu a,b, ⁎ , Lizhen Huang a , Aristidis Kaloudis b , Marit Støre-Valen c a Deparment of Manufacturing and Civil Engineering, Norwegian University of Science and Technology, Gjøvik, Norway, Teknologivn. 22, 2815 Gjøvik, Norway b Department of Industrial Economics and Technology Management, Norwegian University of Science and Technology, Gjøvik, Norway, Teknologivn 22, 2815 Gjøvik, Norway c Department of Civil and Environmental Engineering, Norwegian University of Science and Technology, Høgskoleringen 7A, NO-7491 Trondheim, Norway ARTICLE INFO Keywords: Dwelling type Norway Road energy use Urban density Urbanization ABSTRACT The relationship between urbanization, energy use, and CO 2 emissions has been extensively studied in recent years, however little attention paid to the differences in urban forms. Previous studies implicitly assume that the urban form is homogenous across different urban areas. Such an assumption is questionable as urban form can have many different facets. This paper in- vestigates the effects of urbanization on the road transport energy use by considering different urban forms from a dataset of 386 Norwegian municipalities from 2006 to 2009. Using the Stochastic Impacts by Regression on Population, Affluence, and Technology (STIRPAT) model with an energy use identity equation, the main findings (1) confirm the well-established result that urban density has a negative and significant influence on road transport energy use, and (2) demonstrate that the effect of urbanization partly depends on the level of urban density. These results imply that additional increases in urbanization in dense areas yield greater decreases in road transport energy use per capita. Additional findings posit that (3) there is a non-linear (quadratic) relationship between road energy use per capita and urban population. This implies that an increase in total municipality population over a specific turning point can result in a decrease in road energy use per capita. However, (4) the ratio of urban residential buildings with private gardens has a negative and significant influence on road transport energy use. This im- plies that there may be a trade-off between compact and sprawl city development strategies, highlighting that sustainable energy use requires further investigation. 1. Introduction Around 54% of the world’s population lives in urban areas. This is projected to increase to 66% by 2050 with an extra 2.5 billion inhabitants occupying urban spaces (UN, 2014). Such rapid urbanization has generated a multitude of problems and opportunities for not only the economy, but also the environment as urban transport accounts for more than one-fifth of global carbon dioxide emissions (Liddle, 2013). The growth rate of transport energy use – three quarters of which consumed on the road – is projected to increase 2% annually (Saboori et al., 2014). This means that good understandings of road energy use are required to provide insight into the development of more sustainable cities, although the connections between urbanization and environmental impacts are not http://dx.doi.org/10.1016/j.trd.2017.09.021 ⁎ Corresponding author. E-mail addresses: ypliu.ntnu@gmail.com (Y. Liu), lizhen.huang@ntnu.no (L. Huang), aristidis.kaloudis@ntnu.no (A. Kaloudis), marit.valen@ntnu.no (M. Støre-Valen). Transportation Research Part D 57 (2017) 363–377 1361-9209/ © 2017 Elsevier Ltd. All rights reserved. MARK