Total Ramp Density

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John QPE

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I am looking at the FFS component of an LOS problem where the given is "1 cloverleaf interchange per mile"

The solution uses a TRD of 4, should the TRD not be 2??

HCM states that TRD is the number of ramps (on and off, one direction) located between 3 miles upstream and 3 miles downstream of the midpoint of the segment being studied, divided by 6 miles.

SO:

1 cloverleaf interchange per mile = 2 ramps, one direction, per mile

{(2 *3 miles up) + (2*3 miles down)}/6 miles = 2 ramps/mile

 
Johnster-Monster,

I think your calcs would be ok if we were talking about diamond interchanges. But (full) cloverleaf interchanges have 4 access points per direction, right? So I believe the calc would be (4 * 3 + 4 * 3) / 6 = 4 ramps/mile.

fig7.gif


 
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