plotfollow3: 'plotfollow3' adds a new trajectory to an existing graph.
In cartools: Tools for Understanding Highway Performance

plotfollow3 adds a new trajectory to an existing graph.

1	plotfollow3(cflist, vehicle, uf, kf, ub, leff, t4)

`cflist`	contains information about the lead vehicle, a list
`vehicle`	a vehicle identifier, a number
`uf`	speed (mph) of the following vehicle at time `t0`, a number
`kf`	density (vehicles per mile, vpm) of the following vehicle at time `t0`, a number
`ub`	breakdown speed (mph) for this trajectory, a number
`leff`	effective vehicle length, a number.
`t4`	upper range of plot, a number