Previously, Crossing Cambodia reported on this back in September. The article suggests that possibly as of next week the traffic law could be passed by the parliament, Cambodia's National Assembly. Some caution remains: When the law is passed, the ministry will focus on educating traffic police about the enforcement of the law. How long will that take, optimistically a couple of months?
Anyway the article also highlights the increasing traffic accident situation. It also mentions:
'unofficial figures show that there has been "enormous growth" in the number of vehicles in Cambodia".