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Induced Demand is All Around

The construction of the new “tower” and parking garage at the UNM Hospital began in January, 2021. One lane on westbound Lomas Boulevard has been closed to vehicles since the construction fences went up. That’s over two years that one of our city’s main E/W arterials has been minus one lane of traffic. Has anyone’s life been ruined? Does traffic congestion seem noticeably worse there?


In Philadelphia earlier this month a major overpass on heavily trafficked I95, which carries about 160,000 vehicles a day, collapsed without warning. City officials, local and national media, and even Transportation Secretary Buttegieg all predicted a traffic calamity so long lasting and dramatic that the resultant supply chain disruptions would compound national inflation. What happened? Well, it’s true. The next day, traffic was a hot mess. By the end of the week, though, traffic times for commuters and truckers was pretty much back to normal. Coincidentally, use of the regional transit system went up 14 percent on the lines serving that corridor.


This is what is called “induced demand.” It’s a well-documented phenomenon which works in two directions. When we add an additional lane to a road in order to move more vehicles more efficiently, the  efficiency is short lived. As soon as drivers are used to the new lane, its addition provides no significant time or safety advantage to drivers. Why? When driving appears to become more efficient, more people hit the roads, sometimes literally. Conversely, when we remove a lane, whether to expand a hospital or to reconstruct a bridge or maybe even to create a protected bike lane (!), fewer people drive and traffic efficiencies/drive times stay pretty much true to their former measures. The biggest study of lane reduction impacts on driver behavior examined 70 cases and found that traffic on roads that lost a lane experienced an average reduction in traffic of 41 percent.


What do you say we work to reduce a few lanes on some of our fast and dangerous arterials here in Albuquerque? Maybe we could start on Lomas when the hospital construction is done.



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