Maximum signal spacing calculation

[s.sathish08]

Hi All,

please clarify my doubt,

a) While calculating maximum signal spacing using formulae "d" in the place of "Ht4" or "Ht3" which value has to be substituted, obtained headway time or given headway time?.
d=(Vh*Ht3)-(S+O+L)/2 for 3 aspect...
d=(Vh*Ht4)-(S+O+L)/3 for 4 aspect...

Thanks
sathish

[Peter]

Hi All,

please clarify my doubt,

a) While calculating maximum signal spacing using formulae "d" in the place of "Ht4" or "Ht3" which value has to be substituted, obtained headway time or given headway time?.
d=(Vh*Ht3)-(S+O+L)/2 for 3 aspect...
d=(Vh*Ht4)-(S+O+L)/3 for 4 aspect...

Thanks
sathish

If are starting out to work out a distance based on the headway requirements specified in the exam question, the Ht3 and Ht4 notation is not that relevant as the headway time you are required it delivery is the same whether it is 3 or 4 aspect signalling.

I am not sure what you mean by the "obtained headway". Maybe the following will assist:

If you are looking to get a value for comparison when you are starting out your calculations to work out what number of aspect want, you would put the value given the question into the formula.

If you are testing whether something you have calculated meets the requirement, you would put the value you want to test in there.

If this does not help, can you give an example of where you are using this and wondering what value to enter.

Peter