The second is due to the an audacious driver who tries to pass though there is no space to return to the home lane. This happens rarely. Finally, a jam may occur when each of an adjacent pair of drivers, one on each lane, tries to pass simultaneously. Our update algorithm has been designed to eliminate super jams, as described below. Each site has a state , where 0 represents the absence of a vehicle, a stopped vehicle, a vehicle moving with speed 1 in the positive, resp. negative direction and so on.
First vehicles change lanes, then they advance.
The first condition affects vehicles on the home lane. If the vehicle in from of them is at a distance less than , then they would like to pass that vehicle. However, a pass will only be initiated if there is room far enough ahead on the passing lane, and the number of cars in front of the vehicle it would like to pass is small. Passing occurs randomly, even if all these conditions are met, the probability of changing lanes is denoted . The second condition concerns vehicles in the midst of passing.