The use of reliability of trip arrival times does not normally form part of network performance monitoring and modelling. Reasons to monitor and model reliability of trip times include:
(a) monitoring the performance of road network;
(b) monitoring the performance of public transport networks and services; and
(c) evaluating future options.
Although some national guidelines point the way regarding reliability valuations (UK, New Zealand and Australia), current practice is somewhat lagging behind recommended approaches. There is considerable evidence from stated preference survey results related to demand estimation for toll roads and public transport projects, that traveller’s willingness to pay, extends to reliability of travel time, especially for time-sensitive trips.