Total Ramp Density

[jngraham89]

In PE practice exam from NCEES the following information applies toa four-lane urban feeway.
volume: 2,400 vph (in one direction)
peak hour factor 0.90
base free flow speed 60mph
5% truck traffic in peak hour
12-ft lanes
10-ft outside shoulders
3 interchanges in 6 miles
level terrain
no recreational vehicles

in the solution they came up with a Total Ramp Density of 6 ramps/6 miles=1 ramp/mile.
This is where I am confused. I thought since 3 interchanges in 6 miles the TRD would be 0.5 ramps/mile?

 

[ptatohed]

I am so far removed from this stuff, sorry, but quick thought is Total Ramp Density (TRD) is the on and off ramps in one direction so wouldn't 3 interchanges = 6 on and off ramps?

 

[CharlieHotel47_CE_WER]

I am so far removed from this stuff, sorry, but quick thought is Total Ramp Density (TRD) is the on and off ramps in one direction so wouldn't 3 interchanges = 6 on and off ramps?

That is correct. You have an entry and exit ramp per interchange.

 

[Zuma]

I am so far removed from this stuff, sorry, but quick thought is Total Ramp Density (TRD) is the on and off ramps in one direction so wouldn't 3 interchanges = 6 on and off ramps?

how do we have an entry and an exit in one direction? did you possibly mean in the whole Freeway segment?