Abstract
To grasp railway clearance is important for the safe operation of trains. In view of the difficulties to inspect railway clearance rapidly and precisely from actual positions of rails, this paper proposes a methodology for extracting the track center point of rail clearance gauge and visualizing the clearance gauge by using with Mobile LiDAR Systems directly above the rail. First, two MMSs are settled on directly above rails for data acquisition of the center positions of the railhead. Since the original reference point of the clearance gauge is the middle point of the level line on top of the two rail heads, it is calculated and evaluated using point cloud in every scanline of the laser scanner of MMS. Second, the prototype program has been developed to visualize three dimensional models of the expanded clearance gauge which is consecutively stepped down from curve to straight line along the curve track using center points. Finally, this method was applied to the test rail line where an obstacle was installed 5m up above the rail and it was identified within 0.02m precision inside of to the clearance gauge. The applicability of this method has been verified to both curve and straight tracks.
