New Technology and Experimental Study on Snow-Melting Heated Pavement System in Tunnel Portal

Table 4

Optimal preheating time without thermal insulation layer.

Air temperature (°C)	Target temperature (°C)	Heating power (W/m^2)	Heating time (h)
	2	250	4.33
	2	350	4.83
	2	450	5.25
	2	600	4.83