在已修成的地方道路桥梁中,发现有中型以上的桥梁,特别是木制的,它的桥面纵向倾斜度,从上(下)游侧面观察,有的成不规则曲线形,有的成直线形,有的甚至成两面坡尖形,既不美观,又不能顺畅排除桥上行事部份表面的雨水。这样,雨水会透湿桥面板,日久霉腐,使上部结构早期损坏。一般桥梁当没有设立纵向坡度,或纵向坡度较小时,往往靠着人行道或缘石旁设置的泄水孔(或不大的排水沟)泄水;但在没有行人道的比较长的桥梁中,为了美观和排水,通常在桥面上设纵横向坡度,其大小依桥上铺砌层的种类而定,一般的规定值如下表 Among the roads and bridges that have been completed, more than medium-sized bridges are found, especially in the wood. The vertical gradient of the bridge deck is observed from the upper (lower) side and some are irregularly curved, Linear, and some even into two sides slope pointed, neither beautiful, but also can not be excluded from the action part of the surface of the bridge rain. In this way, the rain will permeate the bridge deck, mold day rot, the early damage to the superstructure. When a vertical bridge is not provided with a longitudinal gradient or has a small longitudinal gradient, a general bridge often discharges by means of a scupper (or a small drainage gutter) provided along the pavement or edge stone; however, in relatively long bridges without pedestrian traffic, Beautiful and drainage, usually vertical and horizontal slope set on the bridge, the size of the bridge depending on the type of paving layer, the general provisions of the following table