Transport Policy 14 (2007) 421–432 Transport policy and environmental impacts: The importance of multi-instrumentality in policy integration Joa˜o Vieira, Filipe Moura à , Jose´ Manuel Viegas CESUR, Department of Civil Engineering and Architecture, Instituto Superior Te´cnico, Av. Rovisco Pais, 1049-001 Lisbon, Portugal Available online 5 June 2007 Abstract Despite the introduction of many instruments in the transport system, they failed to reach their target since gains in global environmental efficiency have not been enough to cope with the consequences of transport growth. The ultimate environmental challenge for transport policy makers is to improve the effectiveness of implementation of policy instruments. This paper explores the concept of multi-instrumentality as a systematic approach for transport policy integration and implementation. Based on extensive literature review, we assess a set of 14 transport policy instruments (weaknesses, strengths and barriers to implementation) and perform a pair-wise analysis of potential synergies in their integrated implementation. Conclusions are drawn on the potential success of multi- instrumentality. r 2007 Elsevier Ltd. All rights reserved. Keywords: Multi-instrumentality; Policy integration and implementation; Transport and environmental policy instruments; Policy assessment 1. Introduction Developments in transport policy have been rather successful in many areas and global trends display extraordinary gains in the ease, cost and safety of move- ment for persons and goods in Europe, over the last 50 years (Viegas, 2003). However, transport growth generates increasing environmental impacts hardened by the growing share of road transportation. Importantly, some improvements were obtained (EEA, 2004) mainly through technological innovation (Interna- tional Energy Agency, 2004) and through the implementa- tion of Transport Demand Management (TMD) instru- ments (Online TDM Encyclopaedia 1 ). However, these have not been sufficient to reduce environmental impacts, mainly because road and air transportation that display higher average external costs have been growing faster than less harmful alternatives (INFRAS and IWW, 2000; EC, 2001). In this sense, we argue that instruments aiming to improve the environmental performance of the transport system have been implemented but, all in all, are failing to reach the goal of curbing current trends of increasing environmental impacts. In complex systems such as transportation, there are many trade-offs occurring and unexpected side-effects from isolated interventions often occur. For example, according to the EEA, road transport has gained a greater and rising share of the freight market until 2005 (EEA, 2006), which indicates that the EU is not fulfilling the objective of stabilising road freight share at its 1998 level, regardless of the massive investments in rail infrastructure and the clarification of charging systems of European roads through the Eurovignette Directive. 2 Traditional approaches to cope with the transport growth such as predict and provide strategies are no longer sustainable options mainly due to the induced demand of enlarged infrastructure capacity (ECMT, 2003). Never- theless, increasing transport demand must be accommo- dated and the combination of transport supply with other types of instruments is potentially a better approach. Planners and decision makers hold a wide and diversified variety of TPIs (Acutt and Dodgson, 1997; May et al., 2003; REFORM, 1999; PROSPECTS, 2001; SPECTRUM, ARTICLE IN PRESS www.elsevier.com/locate/tranpol 0967-070X/$ - see front matter r 2007 Elsevier Ltd. All rights reserved. doi:10.1016/j.tranpol.2007.04.007 à Corresponding author. Tel.: +351 218419715; fax: +351 218474650. E-mail address: fmoura@ist.utl.pt (F. Moura). 1 http://www.vtpi.org 2 Directive 2006/38/EC amending Directive 1999/62/EC on the charging of heavy goods vehicles for the use of certain infrastructures.