When you shut down roadways, you should do so in a manner that does not interrupt the flow of traffic too much. If you do need to close the roadway then you should do so in a matter that doesn't disrupt the flow of traffic by the use of road closure signs, detour signs, notices of the closures via Bleeter, and any other means including but not limited to using the /trafficmenu to redirect AI traffic away from your scene.
When the time comes to shut down the roadway, there are multiple ways that you can go about it in order to cause the least disruptions to traffic. The first way that you can go about doing so is by shutting down the roadway during the night and re-opening it during the daytime hours. The second way is to do it at any time of day but by only closing half the road at a time which allows traffic to still flow through one side by the use of flaggers controlling who can go through in order to avoid any sort of collision. Lastly, another way you can close down a road is by doing a full shutdown during any time of day to do repairs if the repairs are either urgently needed, are going to go across more than 1 day which won't allow traffic through during daytime due to hazards, or if the crews need to work nonstop to fix the issue such as a pipeline bursting under the roadway causing it to flood the road, etc. There may be some more reasons as to why a road would need to be worked on that are not mentioned on this page.