Based on geometry alignment data and speed difference, by stat. Formula are established about the relation between downgrade, curve radius and deflection and speed change.

• 依据样本路段的几何线形数据和速度变化特征，利用统计手段得出了纵坡坡度、平曲线半径和偏角等线形指标与速度变化之间的关系公式，根据这些公式，给出了一定线形组合求解速度特征曲线的方法。