As a general rule, the finer the crossing angle of a turnout, the higher the turnout speed, for example:

1 in 10.5 - 25 km/h
1 in 18.5 - 80 km/h
http://en.wikipedia.org/wiki/Railroad_switch

The geometry of the turnout is the standard design UIC60-760-1:15 with curve radius 760 m and crossing angle 1:15. The simulations were performed for the ...
linkinghub.elsevier.com/retrieve/pii/S0022460X08007475

I recently picked up a bronze LN #4 with the high angle frog - 50 degree. ... It seemed to be producing the type ii chip - the shaving was fine but crinkly. ...
www.sawmillcreek.org/showthread.php?p=961054