The models of collision speed and collision Angle relating to horizontal curve radium and its direction, hard shoulder width and operation speed are derived by regression.

Throughcalculation of temperature rising callused by them, melt criterion is given, the thickness of melted layer near explosive welding interface with small collision Angle is estimated.

This means that not only were they at different altitudes but also their orbits intersected at about a 10-degree Angle. There was no danger of collision.