Public Transit and Congestion Relief

The Moving Beyond Congestion project's Situation Analysis ("SA") cites traffic congestion relief as one of the primary benefits of public transit. Citing the Texas Transportation Institute's Urban Mobility Index, the SA claims that public transit saves the region $1.6 billion in congestion-related costs. (SA, pg. 4)

The 2005 Urban Mobility Report and Chicago Data Tables indicate that congestion on Chicago-area roads is increasing. This finding is in line with the common experience of every auto commuter. We can all agree that stop-and-go traffic is wasteful and soul deadening. What is not apparent from the TTI's data, however, is how effective a major investment in the region's public transportation system to grow the system will be absent the kind of funding, operational and governance changes that the MBC folks are loathe to embrace, much less even discuss.

First, the real-life fact is that even when motorists encounter congestion and significant delay on their trip, they are still likely to arrive at their destination faster than if they took public transit. The Mobility Report's congestion indices are based on the following assumptions: "Free-flow speeds (60 mph on freeways and 35 mph on principal arterials) are used as the comparison threshold." The Mobility Report (pg. 12) defines the Travel Time Index as follows: "The ratio of the travel time in the peak period to the travel time at free-flow conditions." The Travel Time Index for Chicago is 1.57 (Data Tables pg. 2).

If my math is right, then during rush hour the average commuter on the freeway is averaging about 38.2 mph (60 mph/1.57) and the commuter on the arterial roads are averaging about 22.3 mph (35 mph/1.57). This sounds like a shocking reduction, but how would these people fare on the public transit system? The SA helpfully sets out (pgs. 10-12) the average travel speeds on the region's transit system:

Metra rail: 30 mph
CTA rail: 18.5 mph
Pace bus: 14.1 mph
CTA bus: 9.8 mph

Since the CTA bus system carries roughly half of the public transit passengers in the region, the speed differential between private auto and public transit travel for most people is quite high, over 100%. Metra cannot match the speed on the congested freeways at peak period and Pace buses are 50% slower than traffic on arterial streets during the peak of rush hour.

These differentials actually understate the competitive disadvantage of public transit. Auto drivers typically have easy access to their cars. They neither face the wait at bus stops and train stations nor the kind of uncertainty associated with waiting for the next bus or train. Auto travel offers other conveniences--privacy, the ability to make unscheduled stops, the chance to try out one's singing voice--that public transit cannot offer.

Second, despite the travel time advantages of the private auto, the existing transit system delivers substantial congestion relief benefits. The TTI estimates that the system delivers 22 hours in time savings to peak travelers and saves the region almost $1.6 million in congestion benefits. (Data Tables, pg. 2) These benefits are substantial, are worth preserving and should be extended where feasible.

Third, it will take an unprecedented expansion of the public transit system to deliver significant additional congestion relief benefits. The TTI estimates that it would take an additional 182,000 transit riders going forward just to maintain the existing level of congestion. (Data Tables, pg. 2) This is approximately a 9% increase over current ridership levels. Each year would have to see other large jumps in transit ridership just to keep abreast of increases in population, jobs and travel demand. Obviously, such increases are unrealistic, even if the MBC folks hit a home run in Springfield and bring back an additional $300 million annually in operating subsidies plus more capital money. Certainly, no one expects public transit to carry to full burden of fighting traffic congestion. However, is even a 3% growth rate for public transit ridership feasible in the current environment?

Fourth, if public transit is such an effective congestion relief tool, then why haven't we seen strong gains in public transit ridership during the past two decades, as road congestion in the region has worsened quite substantially according to the TTI. (Data Tables, pg. 6) If transit is such an attractive alternative to congestion plagued driving, then why haven't the service boards been inundated by frustrated motorists sick of the grind of rush hour on the expressways? Indeed, the SA admits (pg. 4) that in recent years, as the travel time index was soaring, transit ridership is up a bit but "auto travel is growing even faster." This was also at a time when the benefits from the Illinois FIRST capital program were being felt, which makes transit's poor performance doubly troubling.

There is thus a real question whether in the current operating/road pricing/institutional environment public transit can play an increased role in providing congestion relief. Indeed, it will be a struggle for them just to maintain their current level of effectiveness.

An upcoming entry we will look at whether the capital plans of the service boards are directed at projects likely to provide the most congestion relief benefits for the region.