Both SpeedTraps 1 

Demo of the 'straight' SpeedTrap (use on straight track) and a 'curved' SpeedTrap I also made to work on the 12.5" radius track on my test track which is shown in the video. Shows speed in MPH or KPH.
Build info, print files and software (almost all up) at ....
1fatgmc.com/Ra...
NOTE: SpeedTrap speedometers will record the speed automatically regardless of which direction the loco goes through them.