This single lane pile up is enough to paralyze our road network and wreck our cities because of multiple problems that arise from vehicles not getting to their destination. Here is a simple picture with marked road. By using this combination of a dead end road with roads that lead to and from this main road you change the arrows on the end segment of the main road and with that change the whole usage of the lanes.
If you want to stop a lane from being a forward AND turn lane you have to add new road segments after it to influence the arrows on that part of the road/highway while at the same time adding new road segments to the side of that lane and a sort of a dead end road a bit farther off in the distance from the main road. So while lane arrows control traffic you can control the traffic arrows by how you lay down each next consecutive road segment.
The only way to change a traffic lane arrow, when not using mods, is with the road that comes after it, more specifically, the lane onto which this arrow leads to.
When playing with no mods you have to use some creative means to change the way these arrows work in order to make paths that the traffic AI will use in it's calculation before it spawns a vehicles that is going to use that path. What you must understand to be able to solve this lane usage problem with the traffic AI is that his actions are directly influenced by the white arrows, lane direction arrows, on the roads and highways themselves. This last part of their plan, the lane from which they will turn into another road is where all our problems come from and where player frustration is created. All the vehicles coming in from the region have already planed out routs which include roads which they will drive on, lanes on those roads that they will drive on and places where they will change their lane to be able to turn from a multi-lane road to another road. The regular gameplay starts of vehicles on the regional highway entrances on multiple lanes, which shows us that the traffic AI is capable of utilizing all lanes of a road, in this case the highway. However, this is not the case, as I will write down below. This makes a lot of players conclude that the traffic AI is incapable of using more then one lane and that anything more then two lane roads are a waste of money and space. If you want to find out what makes up for such a high traffic volume, read up on the previous part of this guide which is about vehicles. And to our amusement, horror or annoyance they do this by filling up only one lane out of two out, or out of three or even out of six lanes. The main problem we all have are the traffic jams created when the vehicles in our cities fill up our road capacity to the point that the traffic flow comes to a standstill.