Perhaps stating the obvious but the 4017 Reset function (in addition to clearing any "illegal" states) puts the count back to 0 where the Q0 output is high. In your circuit this puts Red on the E-W direction.
To add some interest to your layout, if your intersection is near a grade-crossing you could have your train-detector (ITAD, isolated-rail, etc.) reset the 4017 to immediately stop E-W traffic going to the RR crossing. I don't know if there is a standard but I see this behavior on traffic signals next to RR crossings near me.
Depending on how you do block detection, it could be as simple as a 10 cent transistor and a couple resistors but no more than, say, 50 cents using an opto-isolator chip.