|More congestion follows more roads. Photo Copyright of The Daily Star|
Basic transport economics teaches us that changes in roadway supply have an effect on the change in traffic congestion. Additional roadways reduce the amount of time it takes travelers to make trips during congested periods. As urban areas come closer to matching capacity growth and travel growth, the travel time increase is smaller. In theory, if additional roads are the only solution used to address mobility concerns, growth in facilities has to be slightly greater than travel growth in order to maintain constant travel times.
Adding roadway at about the same rate as traffic growth will only slow the growth of congestion. But all these assume “other things equal”. No, I am not referring to “induced demand” that could potentially make the cure (road) worse than the disease (congestion). I am referring to the competence, or lack thereof, of those who design, build, and operate the facilities in the public sector.