The NZ Transport Agency's Economic evaluation manual (EEM) provides guidance on the evaluation of journey time reliability in private road vehicle trips. The EEM currently does not provide for the evaluation of reliability for commercial vehicles and freight.
Austroads has recently reviewed the question of including reliability into project economic appraisal but has concluded that a number of methodological and measurement challenges need to be overcome before the concept of travel reliability becomes standard in project appraisal.
There are two general approaches to identifying and assessing the impact of freight time delays and variability. The first approach, usually called the 'factor cost method' involves an analysis of the consequences of lateness in the freight transport operation and the related quantifiable costs. The second approach is to elicit perceived values for journey time, departure and arrival punctuality from the shipper or transporter in relation to cost using any model of shipper or carrier behaviours including stated preference and revealed preference techniques.
The research highlights the need for three main areas of further research: