Impact Evaluation of Transport Interventions: A Review of the Evidence

By David A. Raitzer, Nina Blöndal and Jasmin Sibal

This publication aims to support impact evaluation in the transport sector by assessing what has been produced against what might be possible. It reviews 91 impact evaluations of transport interventions in developing countries, summarizes findings on outcomes, identifies evidence gaps, and proposes ways forward. Most of the studies reviewed find significant effects on at least one of the outcomes investigated. However, impact evaluation has given relatively little coverage to major areas of investment, such as urban and sustainable transportation, transport corridors, and efficiency enhancing measures. New methods and increasing openness of geospatial data provide scope to generate more innovative impact studies.

• Language: English
• Publisher: Asian Development Bank
• Release date: Apr 1, 2019
• ISBN: 9789292615871

Book preview

IMPACT EVALUATION OF TRANSPORT INTERVENTIONS

A REVIEW OF THE EVIDENCE

David A. Raitzer, Nina Blöndal, and Jasmin Sibal

APRIL 2019

Creative Commons Attribution 3.0 IGO license (CC BY 3.0 IGO)

© 2019 Asian Development Bank

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Some rights reserved. Published in 2019.

ISBN 978-92-9261-586-4 (print), 978-92-9261-587-1 (electronic)

Publication Stock No. TCS190095-2

DOI: http://dx.doi.org/10.22617/TCS190095-2

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Notes:

In this publication, $ refers to United States dollars.

ADB recognizes China as the People’s Republic of China and Vietnam as Viet Nam.

On the cover: Impact evaluation needs to consider the effects of transport sector interventions on various sectors (photos by ADB).

Cover design by Joe Mark Ganaban.

Contents

Tables, Figures, and Boxes

Foreword

Strategy 2030 of the Asian Development Bank emphasizes the creation of knowledge from investment operations and the use of evidence from past projects to design new interventions. The Strategy also seeks a more proactive role for research to help to replicate good project practices across Asia and the Pacific region. For these ambitions to be fulfilled, evidence on the intended and unintended effects of interventions needs to be accumulated. Impact evaluation is a central means for generating evidence.

To build a broader body of evidence on what works in development, impact evaluation needs to be mainstreamed across a range of development investments. In recent years, impact evaluation coverage has made substantial progress in the health and education sectors. Although sectors dominated by hard infrastructure, such as transport, account for far more development investment, the number of impact evaluations on these sectors has remained limited. Moreover, transport investments have become very complex and more oriented toward making transport sustainable and inclusive. Along with these innovations has come an increasing array of behavioral assumptions underpinning interventions, which impact evaluations can help to test.

At the same time, transport sector interventions have special challenges for impact evaluation. Many transport investments, such as highways or mass transit, are small-n interventions, which affect large geographies, so that there are insufficient numbers of treated and untreated units for enabling conventional statistical analyses. Transport costs condition where households and firms chose to be located, so that exposure to transport interventions can be endogenous to household and firm characteristics over long time periods. Capturing spillover effects can also be a challenge, as changes to transport costs can be transmitted across large transit networks.

This review is intended to help offer insights