  In this paper, we consider a time-headway model, introduced in Physica A
296:320 (2001), for buses on a bus route. By including a simple no-passing
rule, we are able to enumerate and study the unstable modes of a homogeneous
system. We then discuss the application of the model to realistic scenarios,
showing that the range of reasonable parameter values is more restricted than
one might imagine. We end by showing that strict stability in a homogeneous bus
route requires careful monitoring by each bus of the bus in front of it, but in
many cases this is unnecessary because the time it takes for the instability to
appear is longer than a bus would normally spend on a route.
