Three-layer bridge and construction method thereof

The invention provides a three-layer bridge and a construction method thereof. The three-layer bridge includes a pier, the upper end of the pier is fixedly connected with a bridge abutment. The upperend of the bridge abutment is fixedly connected with a prefabricated slab layer. The upper end of the prefabricated plate layer is fixedly connected with a cast-in-place layer; supporting steel structures are fixedly connected to the two sides of the upper end of the cast-in-place layer. The upper end of the supporting steel structure is fixedly connected with a vehicle and pedestrian layer. A bridge floor layer is arranged above the vehicle and pedestrian layer, a Y-shaped support is fixedly connected to the upper end of the pier and penetrates through the prefabricated plate layer and the cast-in-place layer, the middle of the Y-shaped support is fixedly connected with the vehicle and pedestrian layer, and one end of the prefabricated plate layer, one end of the cast-in-place layer, oneend of the vehicle and ped