An Improved Model for Headway-Based Bus Service Unreliability Prevention with Vehicle Load Capacity Constraint at Bus Stops

Table 1

The level of service classified by 𝐶_𝑣ℎ for fixed-route bus service.

LOS	𝐶𝑣ℎ	𝑃(ℎ𝑖>0.5ℎ)	Comments
A	0.00–0.21	≤1%	Service provided like clockwork
B	0.22–0.30	≤10%	Vehicle slightly off headway
C	0.31–0.39	≤20%	Vehicle often off headway
D	0.40–0.52	≤33%	Irregular headways, with some bunching
E	0.53–0.74	≤50%	Frequent bunching
F	≥0.75	>50%	Most vehicle bunched

Note: (a) The probability 𝑃 means that a given transit vehicle’s headway ℎ_𝑖 will be off headway by more than one-half the scheduled headway ℎ.
(b) Applies to routes with headways of 10 minutes or less.
Source: transit capacity and quality of service manual-2nd edition.