Vertical curve verification 1

[trivedi123]

I have transporter requirement for vertical curve is 7.5" in 50'.
I have A&E report showing profile of vertical . I need help to verify requirement.
Attached is the profile.
Any help will be appreciated.
Thanks

 

[chicopee]

Your transporter requirement being 7.5/(50*12)= 1.25% does not match any number grade number in the elevation plan.

 

[Pinwards]

If the concern is the transporter high-centering on a sharp vertical curve, then have no worry. That's a sag vertical curve, so you're only increasing the clearance underneath, between the axles. And it's a fairly gradual/long one at that for the algebraic grade difference, so should be navigable by almost any road-worthy vehicle.

If the actual longitudinal grade of the road is the concern then see chicopee's answer above.

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[trivedi123]

Thank you both.
I need to check only vertical curve requirement. I have attached the requirement that A&E has to satisfy.
Any help?

 

[BridgeSmith]

Uh, that doesn't look anything like a vertical curve, trivedi...

 

[trivedi123]

Sorry, My bad. Wrong attachment. I am attaching new attachment showing requirement for vertical curve.
Thanks for pointing out.

 

[trivedi123]

Any thoughts?

 

[CarlB]

It's nearly impossible to interpret those figures without accompanying text.
But a 7.5" chord offset to road surface is pretty clear. This equates to a 50' long vertical curve for a 10% difference in algebraic grade. It has a "k" value of 50/10=5.
The design has k values of 130 and greater, so they are much more gradual.
The sharpest curve has a k value of 130. The offset is 4" over a 200' chord, so is much flatter than the 7.5"/50 criterion.

 

[trivedi123]

Thanks CarlB,
Per Chicopee, 7.5"/50x12= 1.25%, according to you grade difference 10%. Is this related? My transporter requirement for vertical curve is 7.5" over 50'.Thanks.

 

[trivedi123]

Cont.
Also for sag curve the grade difference will be of subtraction of two grades, right?

 

[CarlB]

Chicopee was guessing what the criteria was, stated that a change of 7.5" over 50' is 1.25%, a basic calculation of slope. But your criteria is for no more than 7.5" difference between a 50' long chord and the peak (or sag) on a vertical curve. Same result for a crest or sag, a 10% grade change results in a maximum 7.5" vertical difference between the chord and the curve. You'll have to study up on the definition of vertical curves to be certain.

 

[trivedi123]

CarlB,
Thanks. Appreciate your help.

 

[BUGGAR]

I sort of mis-read the title. I was thinking that to verify a vertical curve for correct geometry, you would drive over it quickly with a weight on the seat next to you. A passenger will do. If the curve geometry is correct, the weight (passenger) will feel a constant vertical force throughout the curve, neither further rising or sinking into the seat, once the curve is entered. This is fun to test. Maybe not in your transporter, though.

 

[trivedi123]

Thanks

 

[trivedi123]

Hey CarlB,
Sorry I am not civil engineer and I saw that vertical curve is function of parabolic curve. Is there a formula or method to calculate 7.5" in 50' has grade difference of 10% ?
Appreciate help.

 

[BridgeSmith]

Maybe try this: TXDOT Roadway Design Manual, Vertical Alignment

 

[trivedi123]

Thank you all.

 

[trivedi123]

Need help from road expert. Can anyone explain how to interpret the 7% in attached sketch> it is grade change without vertical curve in road section.

 

[trivedi123]

Also How to interpret note 25C for slope transition?

 

[TerryScan]

The 7% in figure 58.1 is the maximum longitudinal slope mentioned in 25A.

25C is the maximum rate of change in slope. (the instantaneous slope at any two locations 6.5 ft apart on a vertical curve must not be more than 1% different.)