城市道路缓和曲线最小长度研究

摘要:

为提高行车安全性及舒适性，弥补道路缓和曲线长度现行设计方法的不足，本文从多方面对道路缓和曲线最小长度取值进行了研究。针对城市道路缓和曲线最小长度规范取值局限性及设计中存在的问题，分析研究了缓和曲线最小长度的计算方法及规范取值的侧重点，首次提出了满足汽车离心加速度的变化率、考虑驾驶者操作反应时间、超高因素和视觉美观性等4种情况下城市道路缓和曲线最小长度计算模型。计算结果：（1）考虑驾驶者操作反应时间条件下，计算结果与规范取值相适应；（2）考虑汽车离心加速度的变化率条件下，当设计车速小于等于50km/h时，计算结果与规范取值相适应，当设计车速大于50km/h时，计算结果略高于规范取值；（3）考虑超高因素条件下，计算结果为规范取值1.5~3.4倍；（4）考虑视觉美观性条件下，当R为不设超高半径，设计车速小于等于50km/h时，与规范取值相适用，当设计车速大于50km/h时，计算结果为规范取值1.3~2倍。研究结论：（1）当不涉及圆曲线超高情形下，着重考虑汽车离心加速度变化率、驾驶者操作反应时间等因素对缓和曲线长度的影响，当设计车速小于等于50km/h时，缓和曲线最小长度取值与规范取值一致，当设计车速大于50km/h时，缓和曲线最小长度取值比规范取值大5m；（2）当涉及超高因素条件下，应综合考虑汽车离心加速度的变化率、考虑驾驶者操作反应时间、超高因素和视觉美观性等因素对缓和曲线长度的影响。

Abstract:

In order to improve driving safety and comfort and make up for the deficiency of the current design method of road transition curve length, this paper studies the value of road minimum transition curve length from many aspects.?In view of the limitations of the specification for the minimum transition curve length of urban roads and the problems existing in the design, the calculation method of the minimum transition curve length and the emphasis of the specification were analyzed and studied. For the first time, a model for calculating the minimum transition curve length of urban roads was proposed under the conditions of satisfying the change rate of vehicle centrifugal acceleration, considering driver operation reaction time, ultra-high factors and visual aesthetics. The calculation results are as follows: (1) Considering the driver’s reaction time, the calculation result is compatible with the standard value; ((2) under the condition of considering the change rate of vehicle centrifugal acceleration, when the design speed is less than or equal to 50km/h, the calculation result is consistent with the specification value, when the design speed is greater than 50km/h, the calculation result is slightly higher than the specification value; (3) considering the ultra-high factor, the calculation result is 1.5-3.4 times of the specification value.?(4) under the condition of considering visual aesthetics, when R has no superelevation radius and the design speed is less than or equal to 50km/h, it is suitable for the specification value. When the design speed is greater than 50km/h, the calculation result is 1.3 times of the specification value. Research conclusions: (1) When the superelevation of the circular curve is not involved, the effects of factors such as the change rate of centrifugal acceleration and the driver's operation reaction time on the length of the transition curve are emphatically considered. when the design speed is less than or equal to 50km/h, the minimum length of the transition curve is consistent with the value of the specification, and when the design speed is greater than 50km/h, the length of the minimum transition curve is 5m larger than the value of the specification; （2）when the superelevation factor is involved, the influence of factors such as the rate of change of vehicle centrifugal acceleration, driver's operating reaction time, ultra high factors and visual aesthetics on the length of relaxation curve should be considered comprehensively.