Reverse Curves
Reverse Curves
(OP)
Does anyone help me in finding minimum tangent lenghts between reverse curves for rural/local urban strrets? Does AASHTO green book has any info on this? Thanks for the help.
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RE: Reverse Curves
RE: Reverse Curves
"...students of traffic are beginning to realize the false economy of mechanically controlled traffic, and hand work by trained officers will again prevail." - Wm. Phelps Eno, ca. 1928
"I'm searching for the questions, so my answers will make sense." - Stephen Brust
RE: Reverse Curves
RE: Reverse Curves
RE: Reverse Curves
AASHTO does not have any minimum tangent lengths, only minimum lengths of runoff/runout for roads that are superelevated; these runoff/runout distances are generally then considered minimum tangent lengths.
If your road is superelevated, you minimum tangent lengths are driven by the runout/runoff lengths, and a few other design parameters.
If your road is not superelevated, then minimum tangent lengths should be included in your local review agency road design standards - some do not require any at all.
As a designer for numerous low-volume roads, I am usually OK with designing reverse curves with no tangent length, but I do use minimum tangent lengths when designing compound curves ("broken-back") with largely differing radii.
If your new to road design, read Pgs. 229-230 of the PGDHS (2004)(updated "AASHTO Green Book") for some very useful discussion about horizontal road design issues.