1. Safety: If the rainwater outlet is improperly set, it may affect the structural safety of the bridge, increase the maintenance cost of the bridge, and even pose a threat to the safety of people and vehicles below.
2. Environmental impact: The setting of the sewage outlet should consider the impact on the downstream water body and the surrounding environment to prevent the setting of the sewage outlet from polluting the surrounding environment.
3. Laws and regulations: When setting sewage outlets, it should also comply with local laws and regulations and environmental protection standards to avoid being fined or held accountable for violating relevant regulations.
4. Actual situation: The setting of the sewage outlet should be evaluated according to the actual situation, taking into account the topography and water flow under the bridge, as well as the surrounding buildings and roads.