How can we increase the passenger carrying capacity of our roadways? Imagine filling all the empty vehicle seats on the road with people. Then, suppose we fully utilize the roadway 24 hours a day and replace all personal vehicles and freight carriers with buses full of people. How many more people could we move than our busiest highways are moving now? This recent Oregon DOT thought exercise on theoretical maximum roadway capacity shows that our busiest highways are currently operating at about 2% of theoretical capacity (around 98% underutilized.) and hints at the potential for additional transit, TDM and technology investments to increase roadway efficiency.