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Published byLuis Preston Modified over 2 years ago

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InRoads XM Superelevation Lennie Torgerson Engineering Applications Support Team

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Basics Transitions The wizard

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Normal crown Full Superelevation Circular Arc Tangent Runout Spiral Runoff PS PSC PC Runoff Tangent Runout Tangent to curve Spiral curve Basics

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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

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Spiraled Curves 1° or sharper Use spiral transition Runoff = spiral From: Table 5-3 ODOT Highway Design Manual 2003 English

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AASHTO Wizard – Roadway Designer

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AASHTO Wizard 3.5%

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Superelevation Point Controls

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Slope Station Superelevation Diagram - spiral LETL RETL CL PSCPS

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Unspiraled 0°55 and sharper From: Table 5-3 ODOT Highway Design Manual 2003 English Runoff length = normal spiral length

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AASHTO Wizard

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Slope Station Superelevation Diagram – no spiral LETL RETL CL PC

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Non-standard spirals or runoff From: Table 5-3 ODOT Highway Design Manual 2003 English

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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.

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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:

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The math AASHTOODOTInRoads XM L r = length of superelevation runoff, ft = maximum relative gradient, % b w = adjustment factor for number of lanes rotated, based upon number of points on template between Pivot and furthest Range Point. D p-e = distance from Pivot to furthest Range Point, ft e d = design superelevation rate, % L s = length of superelevation runoff, ft s = relative slope, % (same as ) W = distance from ETL to ETL, ft e d = design superelevation rate, % L r = minimum length of superelevation runoff, ft max = maximum relative gradient, % n 1 = number of lanes rotated b w = adjustment factor for number of lanes rotated w = width of one traffic lane, ft e d = design superelevation rate, %

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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:

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AASHTO Wizard

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Slope Station Superelevation Diagram – short runoff PC %

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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!

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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. w is the distance between the axis of rotation and the edge of pavement (or TL) Rotation about CL reduces gradient!

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Slope Station LETL RETL CL Superelevation Diagram – CL rotation

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InRoads XM Interpretation

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L r = length of superelevation runoff, ft = maximum relative gradient, % b w = adjustment factor for number of lanes rotated, based upon number of points on template between Pivot and furthest Range Point. D p-e = distance from Pivot to furthest Range Point, ft e d = design superelevation rate, % D p-e b w e d max (1 st dialog) (looked up)

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Cross Section in Super

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Normal crown Full Superelevation Circular Arc Tangent Runout Spiral Runoff PS PSC PC/PT Runoff Tangent Runout Tangent to curve Spiral curve Basics - review

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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

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Give em a good ride… Thank you for attending…

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