transverse slope on highway

Question

transverse slope on highway

trivedi123 (Structural)

(OP)

2 Mar 17 16:10

anybody has any idea of safe transverse (perpendicular to traffic direction)slope for highway?

Pinwards (Civil/Environmental) · Answer 1 · 2017-03-02 16:23:36

AASHTO's Roadside Design Guide has a lot of information on this subject, with regards to recoverable slopes and roadside obstructions, guardrails, etc. Geotechnical conditions (soil type, rock, etc.) can also govern the slopes you would consider. Without more information you aren't going to get a very detailed answer.

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civilman72 (Civil/Environmental) · Answer 2 · 2017-03-02 17:44:59

I believe the OP was asking about driving surface (paved) cross-slope, not the embankment/sideslope, which is where the Roadside Design Guide comes in.

Most DOT's have superelevation tables, based on speed and road widths. These would serve as a good starting point to determine maximum allowable cross-slopes.

IRstuff (Aerospace) · Answer 3 · 2017-03-02 18:27:11

under what conditions? What's OK for a turn would be different than a straight road.

You could try looking at http://nacto.org/docs/usdg/geometric_design_highwa...

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trivedi123 (Structural) · Answer 4 · 2017-03-02 19:00:37

Thanks everybody.
My case is not to find super elevation on horizontal curve. My road section is straight road.
Do I need to consider anything but drainage for transverse slope. Or 7% slope can cause any safety concern?
Sorry if I have caused any confusion.

IRstuff (Aerospace) · Answer 5 · 2017-03-02 20:05:32

Link above also includes horizontals

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trivedi123 (Structural) · Answer 6 · 2017-03-02 20:16:01

Thanks IRstuff,
The link is a big help.
Thank you.

trivedi123 (Structural) · Answer 7 · 2017-03-30 13:38:25

Any one has come across road smoothness requirement of 1/4" in 10' and 1/8' in 1'. and what is the source of this requirement?

TerryScan (Civil/Environmental) · Answer 8 · 2017-03-30 14:01:37

Typical normal cross slope on roads is 2%.

AASHTO Exhibit 4-4 from the link IRstuff provided shows a table indicating 1.5-2% for high wind, high traffic areas an 2-6% otherwise. There is considerable additional guidance given for selecting a specific slope.

What you call smoothness is also typical in specifications (1/4" in 10' is in our state DOT spec.) The biggest concern is usually "birdbaths" (spots that would collect a pocket of water (ice)).

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transverse slope on highway