Now you start to get into the differences between the various standards :)
In NEMA TS2 (and the more modern ITE ATC), the MMU does enforce a yellow clearance time - you need the light to turn yellow for a period of time before a conflicting phase goes green. Usually this is a few seconds. Changing phases rapidly would likely confuse drivers, but in _theory_ shouldn't cause a collision if people respect yellows.
(believe it or not, in some localities a "red clearance" time - all red - is not required and lights will go from yellow in one direction to green in another.)
In CalTrans TEES, I do not believe the standard calls for the MMU to enforce clearance times - the attack you describe would potentially be possible.
In NEMA TS2 (and the more modern ITE ATC), the MMU does enforce a yellow clearance time - you need the light to turn yellow for a period of time before a conflicting phase goes green. Usually this is a few seconds. Changing phases rapidly would likely confuse drivers, but in _theory_ shouldn't cause a collision if people respect yellows.
(believe it or not, in some localities a "red clearance" time - all red - is not required and lights will go from yellow in one direction to green in another.)
In CalTrans TEES, I do not believe the standard calls for the MMU to enforce clearance times - the attack you describe would potentially be possible.