The Economic Evaluation Notes are arranged in three groups. The first group (TRN-6 to TRN-10) provides criteria for selection a particular evaluation technique or approach
the second (TRN-11 to TRN-17) addresses the selection of values of various inputs to the evaluation, and the third (TRN-18 to TRN-26) deals with specific problematic issues in economic evaluation. The Notes are preceded by a Framework (TRN-5), that provides the context within which we use economic evaluation in the transport sector. All three NPV, IRR, and modified IRR are summary measures of project performance. Each one provides a single figure summarizing the impact of the project on economic welfare. Each of the three measures does, however, give subtly different information: 1) NPV focuses on the total welfare gain over the whole life of the project
and, 2) IRR and Modified IRR focus on the rate at which benefits are realized following an initial transport investment.