Roadworks, are widespread and traffic incidents abound. Reliability for road trips is not measured, but poor, given that one can rely on a number of traffic incidents in every peak period, but not on a predictable trip time. Reliability is the variation in trip time, measured at the frequency deemed to be reasonable, say once in 1,000 trips. The measure has not been established for a representative set of trips for Melbourne because congestion and road safety are much more immediate problems, that must be solved before reliability.
Proven methods for reliability involve excess capacity, redundancy, fully automatic vehicles, multiple sensors, control systems, exclusive track, and no serial queues, but parallel off-line stops, off-line turns, and interchanges.
Requirements: To achieve reliability: vehicle components must be reliable; routes must have redundancy and excess capacity; and all control and propulsion components must have redundancy.