A few mods which are most certainly worth checking out for those who like customization in SimCity games. A few of these DO require OFFLINE mode though!
http://community.simtropolis.com/files/file/29585-offline-only-mod-%E2%80%9Cunidirectional-networks-udon%E2%80%9D/And perhaps the best mod released for SimCity so far. Requires patch 10.1 to be installed. Providing one-way roads!