Suppose that the first lane begins to get congested at a volume of 10,000 vehicles per day. Each additional 1,000 vehicles reduce the speed of all cars on the lane by 1 km per hour. If the road is twice as wide, congestion kicks in at 20,000 vehicles but now declines by 1 km per hour for each 2,000 additional vehicles. The free-flow speed is 100 km/h. Suppose that the only variable cost on this road is the cost of drivers' time, which they value at $10/hour and the length of the road is 50 kilometers. All drivers travel on this full segment.

Find the equations of the PMC and SMC for the one-lane and two-lane roads