Freeway courtesy is just another way of saying Freeway Safety. it has to do with behaving in a way that other drivers expect and can therefore anticipate.

      Perhaps the first thing is the entering of a freeway. Traffic is traveling at 65 mph or better. If you enter the freeway at 45 mph you force other drivers to use brakes or swerve out of your way. This is an excellent way to create a dangerous situation and can result in multiple crashes of cars.

      In San Luis Obispo we have a situation where the original plans for the freeway through town had only three entrances and exits. The freeway was badly needed due to the presence of Cuesta Grade north of town. It is a long grade and encourages drivers to abuse their brakes. If the brakes should fail one was left with the prospect of careening down Monterey Street to Chorro Street where the highway through town took a sharp right angle turn to the left. There were a number of instances where trucks had lost their brakes on the grade and failed to make this turn, went over the curb in front of the mission and wound up in the creek. So the Highway Department was rather desperate to create the present alignment.
      But they could do nothing without the City Council's agreement and they did not agree until four more exits were added. There was not sufficient land left for these exits and entrances or money for that matter. But the desperation made the Highway Department accept the terms of the Council and the freeway was built. Work in recent years has ameliorated to a reasonable degree the short entrances by allowing an alternative lane that exits at the next opportunity.

      The short entrances however encouraged many people without a great deal of freeway experience to enter the freeway at a dangerously low speed. Fortunately traffic here is light enough to reduce the danger. If one entered a freeway at these speeds in a place like Los Angeles, an accident would be almost impossible to avoid.

      So, the rule is to be at least 60 miles per hour when one enters a lane on the freeway. Lower speeds presents a situation akin to trying to poke your figer into a fan without getting hit by the blades.

      The next most discourteous thing some drivers do is to not recognize anything but the far left lane. It would appear that they feel if they are driving the speed limit they have the right to monopolize the "fast lane". This forces people to either queue up behind them, often too close, or to pass on the right which has some danger. I was a passenger in a car once where the driver went 90 miles from San Luis Obispo to Santa Barbara without leaving the left lane once. I will never ride with that driver again!

      So the correct method is to stay in the right lane as often as possible and use the left lane for passing. One should keep their eye on the other traffic and make it possible for the traffic behind to do what they want to do. This will keep you out of trouble. If someone wants to go 90 mph, why irritate them by bottling up the freeway and perhaps encoouraging them to take a chance which may involve you in an accident.
      I once saw an example of this when two cars were racing down highway one, two lanes and two way traffic and they came upon a car at the speed limit but slower than they were. One passed in the oncoming traffic lane and the other passed on the right using the shoulder! One has to remember that there are people like that on the same road with you.

      An exception to this exists when passing through a town where there are freeway entrances. Knowing that there are people that will creep out onto the freeway at 45 mph it makes sense to plan your travel through the area so that you have no one at your side, so that if a lane change becomes necessary, that lane will be open. While this is not really possible in Los Angeles, it is possible in most of the smaller towns.