Curb gutter Roadway Cross Slope formula |
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\( m_c \;=\; \left( \dfrac{ Q \cdot n }{ 0.56 \cdot m_l^{1/2} \cdot q^{8/3} } \right)^{3/5}\) (Curb Gutter Roadway Cross Slope) \( Q \;=\; \dfrac{ 0.56 }{ n } \cdot m_c^{5/3} \cdot m_l^{1/2} \cdot q^{8/3} \) \( n \;=\; \dfrac{ 0.56 }{ Q } \cdot m_c^{5/3} \cdot m_l^{1/2} \cdot q^{8/3} \) \( m_l \;=\; \left( \dfrac{ Q \cdot n }{ 0.56 \cdot m_c^{5/3} \cdot q^{8/3} } \right)^2\) \( q \;=\; \left( \dfrac{ Q \cdot n }{ 0.56 \cdot m_c^{5/3} \cdot m_l^{1/2} } \right)^{3/8} \) |
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| Symbol | English | Metric |
| \( m_c \) = Roadway Cross Slope | \(dimensionless\) | - |
| \( Q \) = Gutter Flow Rate | \(ft^3 \;/\; sec\) | - |
| \( n \) = Manning's Roughness Coefficient | \(dimensionless\) | - |
| \( m_l \) = Gutter Longitudinal Slope | \(dimensionless\) | - |
| \( q \) = Gutter Flow Width | \(ft\) | - |
Curb gutter roadway cross slope are design features of a street that work together to manage stormwater runoff. The roadway cross slope is the angle at which the surface of the road is inclined from the center towards the edges. This gentle slope, typically expressed as a percentage, ensures that rainwater flows laterally off the driving lanes.
At the edge of the roadway, the curb acts as a barrier, and the gutter is the shallow channel formed between the curb and the road surface. The gutter cross slope is the transverse slope within this channel, directing the water along the gutter towards designated drainage inlets. This combination of roadway cross slope and gutter cross slope efficiently moves water away from the traveled way, preventing ponding, reducing the risk of hydroplaning, and contributing to overall road safety and longevity.
