Substantial investment has been made at national and European level in tran
sport infrastructure over the past 50 years and is likely to continue in th
e future. The need to appraise transport projects in economic and social te
rms has developed alongside this in both scope and complexity. The state-of
-the-art in the economic appraisal of transport projects is reviewed, progr
ess is assessed and future challenges are identified. The review addresses
the general framework, treatment of major impacts, presentation of outputs
and issues such as uncertainty. It draws on national practice in Western Eu
ropean countries, which varies substantially reflecting a range of cultural
and economic differences. Some points of commonality exist and the princip
le of monetizing direct transport impacts is generally accepted. Progress h
as been made towards the measurement of environmental impacts, but the asse
ssment of the wider impacts remains underdeveloped. Increased sophisticatio
n and complexity has brought increasing data and presentation requirements,
where computerized decision support methods have potential. Many challenge
s exist for the future of appraisal and the review is concluded with a disc
ussion of some key issues. At the heart of these is the continuing debate o
ver the relative roles of national and European government in decision-maki
ng and resource allocation.