The invention discloses a flat slab ceiling screen. The flat slab ceiling screen comprises a smoke detector (1), a marking controller (2), a control line (3), connecting lines (4), a reserved steel bar (5), a telescoping device (6), a smoke barrier plate (7), a floor slab (8), angle iron (9) and a supporting frame (10). By adopting the above structure, the smoke barrier plate does not affect the space at normal time, and is horizontally fixed below the floor plate, and the smoke barrier plate automatically sags through the smoke detector and the controller when a fire hazard occurs in order to realize smoke baffle, so the floor height is reduced, and energy is saved. The invention also discloses a novel vehicle gateway height limiting rack. The novel vehicle gateway height limiting rack comprises a height limiting rack crossbeam (1), a signboard (2), a solar photovoltaic cell panel (3), a horizon (4), a height limiting rack column (5), a storage battery (6) and a charging controller (7). By adopting the above structure, the solar photovoltaic cell panel converts solar energy into electric energy stored in the storage battery during the day, and powers up the LED lamp of the signboard at night, so the renewable clean energy solar energy is used, and pollution is reduced.