Minimum Vertical Curve Length

[Eddie W. Shore]

The program MVCL calculates the minimum vertical curve length for sight distances for crest curves (curve that rises then falls) and sag curves (curves that falls than rises). The equations used were determined by the AASHTO (American Association of Highway and Transportation Officials of Washington, D.C.).

HP Prime Program MVCL

Code:


EXPORT MVCL()
BEGIN
// Minimum stop speed
LOCAL g1,g2,a,c,l,s,g;

MSGBOX("Break = 2.5 s,
 Decel = 11.2 ft/s^2");

LOCAL l1:={15,20,25,30,35,40,45,
50,55,60,65,70,75,80};

LOCAL l2:={80,115,155,200,250,
305,360,425,495,570,645,730,
820,910};

INPUT({g1,g2,{c,l1}},"MVCL",
{"Grade1%:","Grade2%:",
"Speed:"});

s:=l2(c);
a:=ABS(g1-g2);

l:=2*s-2158/a;
IF s<l THEN
l:=a*s^2/2158;
END;

g:=2*s-(400+3.5*s)/a;
IF s<g THEN
g:=(a*s^2)/(400+3.5*s);
END;

PRINT();
PRINT("Stop speed (ft)");
PRINT("Crest curve: "+l);
PRINT("Sag curve: "+g);


END;

Example 1:
Grade 1: -1.75%
Grade 2: 2.25%
Design Speed: 40 mph

Result:
Minimum Vertical Curve Length
Crest Curve: 70.5 ft
Sag Curve: 243.125 ft

Example 2:
Grade 1: -1%
Grade 2: 1.7%
Design Speed: 50 mph

Result:
Minimum Vertical Curve Length
Crest Curve: 50.740740741 ft
Sag Curve: 150.925925926 ft

Source:https://edspi31415.blogspot.com/2019/02/...tical.html

Michael R. Lindberg, PE “Civil Engineering Reference Manual for the PE Exam” 11th Ed. Professional Publications, Inc: Belmont, CA. 2008. ISBN 13-978-1-59126-192-2

Link to blog post:

[DrD]

Your program led me to think about the derivatives of position, first principles in mass and acceleration, and crash analysis. I know these things have been studied very well, but I don't think this subject has been implemented as one program, on the prime!

It would be enlightening to see consequences, computationally derived, animated, and graphically displayed; using related analytical formulas! Instead of the big bang, this could be, (sort of), the little bang, (unless you happened to be the inside an involved vehicle)!

-Dale-