Compatible with most wooden train toy sets (like Thomas the Tank Engine). I wanted to try a different kind of connector, so I went with an equilateral triangular connector. Only later did I realize that this geometry won't necessarily play nicely with the geometry of these sets, but I've not had any problems.

SolidWorks file is for SW2015. STEP file is available if you can't read SW2015 files.

See my other designs for train tracks as well:

Rail Connector - http://www.thingiverse.com/thing:1779150
Flexi Track - http://www.thingiverse.com/thing:1589228
T Junction - http://www.thingiverse.com/thing:1579594
Cross Junction - http://www.thingiverse.com/thing:1779661