The Gita provides a psychological ladder: Desire leads to anger, anger leads to delusion, delusion leads to loss of memory, and loss of memory leads to the ruin of reason.
From attachment comes desire, and from desire comes anger.
From anger comes delusion; from delusion comes loss of memory... and thus the man perishes.
Lust, Anger, and Greed are the three gates to hell. Abandon them.
Road rage happens because your 'desire' for an empty road is frustrated. By recognizing the root as a selfish desire, you can pause before the anger turns into a destructive action.