Going to comment on the lane closure topic and how others travelling to the end of the closed lane either impede or help the flow of traffic.
Please play with this website.
http://www.traffic-simulation.de/
More specifically, choose the lane closure option. Tweak the options a little bit and you will notice two things. One is that flow is best when vehicles merge ahead of time when the speed different between both lanes is negligible. Second, as soon as a vehicle travels up the closed lane to the end and is forced to merge into traffic, the inability to get to speed instantly slows down the traffic flow. So merge ahead of time and this wouldn't happen.
Now, that theory is completely thrown out the window because you have rubberneckers and it only takes one person to travel to the end to royally screw up the flow for everyone. That is, if they are allowed to merge
As for the main topic on hand, slower traffic stay right.... try using the simulation "Uphill Grade". The trucks (black) are the slower traffic and when not in the right lane, hold up the left lane considerably.