The structure design of the project is diverse and novel, there are many types of construction methods and frequent process changes, the tunnel entrance adopts the three-layer 7-hole three-dimensional superimposed design of highway and rail transit tunnel, and the underground tunnel excavation has a maximum section area of 392㎡. The minimum thickness of the upper and lower tunnels is only 2.03m, which is a typical shallow-buried, large-span, super-close-range multi-cavity superimposed tunnel group. It is a world-wide technical problem. The project adopts the lower orbital loop double-layer two-line + upper-level Hongyan Village tunnel foundation grouting reinforcement + upper span beam and slab structure + zone control excavation and successfully achieved super-small clearance and over-span construction.