The HSR Nangang Station started operation on Jul. 1, 2016. Nangang extension line construction adopted the JIS60 profile rails and started from the north end of Taipei Main Station to the end of Nangang Station, in other words from (1K+000) to -(3K+583). The rail welding procedure is outlined as follows: the rail depot is set at the daylighting section in the vicinity of Dakeng River, then, 25-meter standard length rails are welded via flash-butt welding (FBW) into 200-meter long rails. The FBW method uses the welding machine to melt the ends of the two rails via high-voltage current then applies axial pressure on the ends for extrusion and welding. The entire welding process is automatically controlled via computer settings.
There are a total of 822 weld craters generated via FBW in the rail depot of the Nangang extension line. Each crater must go through four grinding procedures to reach the smoothness requirements (1.5-meter range): 0 ~ + 0.2mm for rail head and gauge side; <1mm for rail foot. The welding quality will be determined by hand-held ultrasonic flaw detectors (UT) and magnetic detection equipment (MT) and the rail number will be sprayed on the rail at 20 cm away from the crater. Finally, the 200-meter long rails will be moved to the construction site to assemble with sleepers and fastenings forming track frames and concrete will be poured subsequently.
As for the gap in between 200-meter long rails and the connecting points with turnouts, the thermit-welding (TW) method is utilized which melts the solder agent via a crucible and then lets the agent flow into the mold to bind the rail. This process also requires smoothness and quality check of the craters upon completion. There are a total of 342 craters generated via TW method connecting a 9.5-meter consecutive long rail from Taipei Main Station to the north end of Nangang Station.