Tunnel sunshade with adjustable brightness

The tunnel sunshade is arranged on a tunnel portal highway and comprises an arched sunshade frame, shading blades are arranged in all openings in the sunshade frame, a plurality of transmission rods capable of moving back and forth in the longitudinal direction of the highway are supported below the sunshade frame, the transmission rods are annularly arranged along the sunshade frame, guide rods located in the transverse direction of the highway are arranged in all the openings, and the shading blades are arranged in all the openings. The shading blades are provided with long-strip-shaped guide grooves formed in the longitudinal direction of the road, the guide rods are slidably located in the guide grooves, the same ends of all the shading blades are hinged to the transmission rods through hinge shafts, the hinge shafts are located in the transverse direction of the road, and the transmission rods are driven by a driving mechanism fixedly arranged on the shed frame to move. The driving mechanism is electrica