Table 2: The ranges of RDI and corresponding damage degrees.

RDI	Damage degree	Damage Description
RDI≤1.5	Intact	No damage or little damage to roadbed or road surface; no influence to traffic capacity.
1.5<RDI≤2.5	Slight damage	Little subsidence or uplift on road surface; little influence to traffic capacity; slight repair is needed.
2.5<RDI≤3.5	Medium damage	Obvious seismic damage to roadbed and road surface; moderate influence to traffic capacity; repair is needed to make traffic capacity back to normal.
3.5<RDI≤4.5	Severe damage	Severe fracture to roadbed and road surface; sever influence to traffic capacity; traffic is limited until major overhaul.
RDI>4.5	Destroyed	Severe fracture and dislocation to road surface; roadbed collapsed; traffic function lost resulting in traffic congestion.