InRoads XM
Superelevation
Lennie TorgersonEngineering Applications Support Team
Basics
Transitions
The wizard
d
ncw
d
e
eb
ewn1
)( 1
Normal crown
Normal crown
Full Superelevatio
n
Circular Arc
Tangent Runout
Spiral Runoff
PS
PSC
PCRunoff
Tangent Runout Tangent to
curve
Spiral curve
Basics
Give ‘em a good ride…1. Curves 1°and sharper Use spiral transition Runoff length = spiral length
2. Unspiraled curves 0°55’ and sharper Runoff length = normal spiral length
3. Standard spirals cannot be attained Use longest of three solutions
Guiding Principles
Spiraled Curves 1° or sharper Use spiral
transition Runoff = spiral
19215.0
4)24(min L
From:Table 5-3ODOT Highway Design Manual2003 English
wdr b
ewnL
max
1)(
AASHTO Wizard – Roadway Designer
AASHTO Wizard
3.5%
AASHTO Wizard
Superelevation Point Controls
Slo
pe
Station
0
0.02
-0.02
0.04
-0.04
Superelevation Diagram - spiral
LETL RETL
CL
PSCPS
Unspiraled 0°55’ and sharper
From:Table 5-3ODOT Highway Design Manual2003 English
Runoff length = normal spiral length
AASHTO Wizard
450
450
Slo
pe
Station
0
-0.02
0.08
Superelevation Diagram – no spiral
LETL RETL
CL
PC
450’
0.02
Non-standard spirals or runoff
From:Table 5-3ODOT Highway Design Manual2003 English
LETL RETL
CL
Relative Gradient – grade difference/runoff
“…the length of the superelevation runoff should be based on a maximum acceptable difference between the longitudinal grades of the axis of rotation and the edge of pavement.”
Relative Gradient – spiral or spiral runoff
r
d
L
we
From my earlier example of a 4°30’ curve, 50 mph, with an 8% super, runoff length of 450’, and 2-12’ lanes rotating about low side ETL:
%43.0'450
%8'24
x
The math
wdr b
ewnL
max
1)(
s
WeL ds 2
AASHTO
ODOT InRoads XM
•Lr = length of superelevation runoff, ft = maximum relative gradient, %•bw = adjustment factor for number of lanes rotated, based upon number of points on template between Pivot and furthest Range Point.•Dp-e = distance from Pivot to furthest Range Point, ft•ed = design superelevation rate, %
•Ls = length of superelevation runoff, ft•s = relative slope, % (same as )•W = distance from ETL to ETL, ft•ed = design superelevation rate, %
Lr = minimum length of superelevation runoff, ftmax = maximum relative gradient, %n1 = number of lanes rotatedbw = adjustment factor for number of lanes rotatedw = width of one traffic lane, fted = design superelevation rate, %
wdepr b
eDL
max
)(
Example
'192%5.02
%8'24
2
x
x
s
weL ds
From my earlier example of a 4°30’ curve, 50 mph, with an 8% super, and 2-12’ lanes rotating about low side ETL:
AASHTO Wizard
192
192
Slo
pe
Station
0
-0.02
0.08
Superelevation Diagram – short runoff
PC
192’
0.02
50%
Relative Gradient – short runoff
r
d
L
we
Example of a 4°30’ curve, 50 mph, with an 8% super, runoff length of 192’, and 2-12’ lanes rotating about low side ETL.
%1'192
%8'24
x
'192%5.02
%8'24
2
x
x
s
weL ds
Exceeds max. relative gradient!
Relative Gradient – short runoff
r
d
L
we
Example of a 4°30’ curve, 50 mph, with an 8% super, runoff length of 192’, and 2-12’ lanes rotating about centerline.
%5.0'192
%8'12
x
w is the distance between the axis of rotation and the edge of pavement (or TL)
Rotation about CL reduces gradient!
Slo
pe
Station
LETL RETL
CL
Superelevation Diagram – CL rotation
InRoads XM Interpretation
InRoads XM Interpretation•Lr = length of superelevation runoff, ft = maximum relative gradient, %•bw = adjustment factor for number of lanes rotated, based upon number of points on template between Pivot and furthest Range Point.•Dp-e = distance from Pivot to furthest Range Point, ft•ed = design superelevation rate, %
wdepr b
eDL
max
)(
Dp-e
bw
ed
max(1st dialog)
(looked up)
Cross Section in Super
Normal crown
Normal crown
Full Superelevatio
n
Circular Arc
Tangent Runout
Spiral Runoff
PS
PSC
PC/PTRunoff
Tangent Runout Tangent to
curve
Spiral curve
Basics - review
Curves 1°and sharper Use spiral transition Runoff length = spiral length
Easy to use AASHTO Wizard without editing
Unspiraled curves 0°55’ and sharper Runoff length = normal spiral length
Edit “Calculated Runoff Length” in Wizard
Standard spirals cannot be attained Use longest of three solutions Edit “Calculated Runoff Length” in Wizard
Guiding Principles - review
Give ‘em a good ride…
Thank you for attending…