Induced demand in the context of vehicle capacity simply means that building more space for cars encourages more people to use them. If I live in the suburbs and the city widens the freeway into downtown I might take a few extra trips into the city every month or decide that taking a job in the city is now feasible. The increase in average highway travel speeds also brings more distant suburbs and exurbs within driving distance, which encourages more development at the current sprawl boundary and beyond. These and other effects lead to more cars using the highway until the excess capacity is soaked up and traffic is just as bad as it ever was. According to most studies, about 80-90% of the excess capacity is soaked up within just five years.
Phillips then provides this chart (which is somewhat dubious due to the absence of quantifying data or source, but nevertheless works for illustrative purposes):
As you know, last year the State Legislature passed a Transportation Bill that projects $4.4 billion in transportation projects over the next six years, funded by a progressively increasing gas tax and/or internet tax revenue. Of the first $1.2 billion, over $600 million is slated for MARC and other rail transit: MARC Enhancements $100M, Red Line $170M, Purple Line $280M, and Corridor Cities Transitway $100M. You can read about the planned road improvements here (includes $49 M for construction on widening US 29 northbound to three lanes from Seneca Drive to MD 175 in Howard County).
Many on the right have accused the Governor of putting the burden of rail transit on drivers...and they are right. Every time we fill up our tank, we are helping to subsidize rail programs, which require a lower price point for viability due to lower income users. Those same people say mass transit doesn't work, pointing to under-utilized bus routes and empty light rail trains. They would much rather point that money into capacity, even with the acknowledgement that we are just going to use it up in the next five years.
Transportation is the very definition of a holistic system. Each part is dependent on the next from stop lights to bus stops to railway. If rail or bus can't get you where you need to go, its availability is of no use. Ah, but what opportunities open up with an expanded rail system? What if you did have access to rail and it got you where you needed to go? We've already discussed how rail is good for single occupancy drivers, but in the context of Shane Phillips's piece above, rail creates an entirely new artery with regulated capacity (trains can only hold so many people).
Here in Howard County, we are still a far way off from having reliable cheap rail that will get us where we need to go, but we should expect transit alternatives within the next 10 years. In the interim, transit planners and government leaders will need to evaluate how additional capacity can relieve traffic congestion rather than just make more room for it. Without both, we are going to need more audio-books.
That's all for today. Have a great Wednesday doing what you love!
