Converting Calculated headways to signal spaces.

[KenD]

i would like to know how you convert calulated headways to required signal types.

eg, A line has a civil line speed of 160km/h However the trains that use the line are only able to do a max of 120km/h.

Operationally thru trains require a headway of 3mins and stopping trains 6mins.

This working headway would be 125% of the calulated headway

I used the standard braking distance of 1189m, overlap 183m, 10sec for sighting. assume gradient of level.

For 4 aspect signalling I calulated a headway of 75 sec

For 3 aspect signalling 93 sec.

Would graphing help?