Congestion is a function of the capacity of a roadway, and the number of vehicles trying to use it at a given point in time. I'd suspect that the only thing any

Congestion is a function of the capacity of a roadway, and the number of vehicles trying to use it at a given point in time. I'd suspect that the only thing any given citizen is able to do is reduce the number of vehicles at a given time. This means either you don't drive (at that time), you car pool, or you take public transport. Assume all drivers like to maintain a gap of approximately 3 seconds between them and the vehicle in front of them. That means that for a single lane, there is a maximum rate of 1 car every 3 seconds at any given speed. If two lanes at maximum capacity merge together, ideally they 'zipper' together but there will no longer be a 3 second gap between cars, so everybody has to slow down. Twice as many cars in the same amount of space suggests to me that everybody now needs to go half as fast, and traffic backs up. The same applies for multi-lane roads. A 4 lane highway has a capacity of 4 cars every 3 seconds, however the effects of mergers will diffuse across the lanes somewhat. Interestingly, we can treat slower vehicles in the same class as mergers, and bottlenecks. Consider a gentleman in his vintage whatever going 60kph on a 3 lane, 100kph road. Aside from being dangerous, we can actually consider this to be a moving merger from 3 lanes to 2. Now consider a leisurely cyclist at 35kph, or a broken down car in a side lane. The slower a road user is travelling relative to traffic, the more they appear like a fixed merger. We can also consider erratic movements by other drivers, which cause other road users to slow down in a similar category. Ideally, one should travel when roads aren't at capacity. That means that users are have no longer hit their 3 second limit and have perhaps 5 second spacing, or are even unable to see the car in front. This affords higher speeds, more predictable behaviour, and a more peaceful commute for everybody. If you can't avoid travelling when roads are at capacity, your only option is to reduce the number of vehicles on the road. Car pool or take public transport. If all users went from a single road user per vehicle, to four per vehicle, demand would be reduced by 400%. Interestingly, you might also consider riding a motorcycle. When cars are at a standstill, motorcycles are able to filter through slow and stopped traffic. Any given car replaced with a motorcycle will increase capacity slightly depending on traffic circumstances. Obviously, one should evaluate their interest and risks associated with such a decision before making the leap. A confident driver making the transition to an unconfident motorcyclist may not have a net positive outcome. Unfortunately, due to the bottleneck case described above, I wouldn't recommend cycling unless suitable bike trails are available or traffic speeds are low enough.