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InRoads XM. Superelevation Lennie Torgerson Engineering Applications Support Team. Basics Transitions The wizard. Basics. Normal crown. PS. PSC. Tangent Runout. Circular Arc. Spiral curve. Spiral Runoff. Full Superelevation. PC. Runoff. Tangent Runout. Tangent to curve.
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InRoads XM Superelevation Lennie Torgerson Engineering Applications Support Team
Basics Transitions The wizard
Basics Normal crown PS PSC Tangent Runout Circular Arc Spiral curve Spiral Runoff Full Superelevation PC Runoff Tangent Runout Tangent to curve Normal crown
Guiding Principles • Curves 1°and sharper • Use spiral transition • Runoff length = spiral length • Unspiraled curves 0°55’ and sharper • Runoff length = normal spiral length • Standard spirals cannot be attained • Use longest of three solutions • Give ‘em a good ride…
Spiraled Curves 1° or sharper • Use spiral transition • Runoff = spiral From: Table 5-3 ODOT Highway Design Manual 2003 English
AASHTO Wizard 3.5%
Superelevation Diagram - spiral CL LETL RETL PS PSC 0.04 0.02 Slope 0 -0.02 -0.04 Station
Unspiraled 0°55’ and sharper • Runoff length = normal spiral length From: Table 5-3 ODOT Highway Design Manual 2003 English
AASHTO Wizard 450 450
Superelevation Diagram – no spiral CL LETL RETL PC 0.08 Slope 0.02 0 450’ -0.02 Station
Non-standard spirals or runoff From: Table 5-3 ODOT Highway Design Manual 2003 English
CL LETL RETL 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 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:
The math AASHTO ODOT InRoads XM Lr = minimum length of superelevation runoff, ft max = maximum relative gradient, % n1 = number of lanes rotated bw = adjustment factor for number of lanes rotated w = width of one traffic lane, 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= 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, %
Example 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
Superelevation Diagram – short runoff PC 50% 0.08 Slope 0.02 0 192’ -0.02 Station
Relative Gradient – short runoff 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. Exceeds max. relative gradient!
Relative Gradient – short runoff Example of a 4°30’ curve, 50 mph, with an 8% super, runoff length of 192’, and 2-12’ lanes rotating about centerline. Rotation about CL reduces gradient! w is the distance between the axis of rotation and the edge of pavement (or TL)
Superelevation Diagram – CL rotation CL LETL RETL Slope Station
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, % Dp-e bw ed max (looked up) (1st dialog)
Basics - review Normal crown PS PSC Tangent Runout Circular Arc Spiral curve Spiral Runoff Full Superelevation PC/PT Runoff Tangent Runout Tangent to curve Normal crown
Guiding Principles - 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
Thank you for attending… • Give ‘em a good ride…