If traffic statistics are to traffic fans as sports statistics are to sports nuts, we who are addicted to the traffic pages should have no embarrassment indulging our fascination in the SR 520 tolling project daily data feed from the Washington State Department of Transportation: a full-color array of 20 maps, 162 explanatory graphs and 37 tables on traffic waves and ripples all around Seattle and its suburbs from the SR 520 tolling.
Unfortunately, as befits the topic’s true complexity this detail, which has to be requested, is intriguing to gaze upon but both too detailed and too transitory from day to day to neatly summarize. So, like baseball slugging percentages and football quarterback efficiency ratings, a bit of selection and personal opinion is necessary for stimulating spirited discussion.
But first, some context. The start of tolling on SR 520 followed by less than two months the voters’ rejection of Tim Eyman’s I-1125 attempt to slam the door on modern tolling in our state. It’s important for Olympia to have heard unequivocally that voters are prepared to see what may happen with tolling. From my own efforts opposing I-1125, including a lot of opportunity for thought about where tolling might be appropriate and how much money it could raise, I came away with great caution toward bullish suggestions that tolling offers more than a partial contribution to the gaps in future transportation funding.
Tolling must be used as a fine-edged tool, not a financing blunt instrument, because the traffic-altering byproducts of careless tolling could have negative and inefficient effects instead of the positive outcomes we should be seeking. And I continue to strongly support the I-405 Express Toll Lane program, which will eventually add a lane in each direction from downtown Bellevue to Woodinville/Bothell.
As on I-405, tolling’s great promise is something apart from a mere construction-financing tool. This more powerful promise — necessarily using variable pricing that constantly tunes the price to fit the immediate circumstances of traffic demand and road supply — lies in the ability to make roads flow more smoothly and produce efficiency benefits, increasing the economic value of infrastructure investments. (In the I-1125 discussion, many voters and commenters clearly got this basic economic point; I-1125’s attack on variable tolling was one of its fatal paths to downfall.)
The greatest importance of the SR 520 program lies in what it will show about making roads more efficient. It’s why the results are being watched not only here but also around the country, and it’s precisely why the U.S. Department of Transportation in 2007 committed more than $150 million to support this program across Lake Washington.
The most encouraging results in the traffic numbers so far are not surprising, but interesting, problematic and unsettled questions also lurk in the details of the early data. It’s already possible to see the huge potential for tolling to point us toward ways to improve our transportation system. So it’s important from the outset to look at implications in the early numbers that remind us how carefully this path must be taken.
For me, the performance of a modern tolling program is chiefly important in relation to two meta-truths about transportation systems and traffic. The first is that traffic congestion is a product not principally at least of too few lanes of roadway but of too much unevenly timed demand. This is the heavy peak use — the daily morning and afternoon surges of drivers and their vehicles that clog the otherwise largely open roads into stop-and-go molasses.
The second is the counter-intuitive but widely agreed upon fact that during peak periods, a large share of the cars and drivers — mixed in with the expected work-commute trippers — are making non-work related trips. Generally accepted estimates of non-work-related volumes run to 40 to 50 percent of peak period trips. Those trips can’t all be made at another time or in another way, but many of them can or will be when it’s in the drivers' and passengers' interest to do so.
We’ve invested untold billions in building and maintaining highways and we face staggering monetary, environmental, and social costs of undertaking to build even more. It’s therefore axiomatic that gaining more efficient use of what we already have — the roadway stock (including the transit systems that run on the roads themselves) — is the first imperative of transportation improvement policy. That’s why low-cost/high benefit programs to speed the clearing of freeway traffic incidents became so prominent on WSDOT and the Washington State Patrol’s agenda almost a decade ago, when experts around the country were noting that traffic-disrupting incidents play such a big role in many of the worst back-up nightmares.
To tolling: the big payoff for making efficient use of roadway investments would be to reshape the daily curve of traffic demand. You can then shave the peaks, fill in the valleys, smooth the traffic flow across the day, save fuel and reduce emissions, speed freight, improve the reliability of expected travel times, and cut everyone’s personal exposure to delay and aggravation.
And, by improving the efficiency with which roads are used, we also can move to capture the really big savings in future transportation costs and trouble, because we then can gauge and pursue our needs for more investments based on how roads should perform, not on how we suffer today from traffic performance in the daily boa constrictor grip of peak-hour congestion. Efficiently used roads will always be smart infrastructure, helping to support a productive economy.
SR 520 tolling really is a national breakthrough for showing how to manage existing transportation systems as if we really cared about the efficiency of road performance and how to do so with the forward-looking techniques of toll collecting and accounting. However, like many groundbreaking efficiencies in any economic sector, SR 520 tolling is an imperfect or, perhaps better stated, an incomplete experiment.
The main flaws in SR 520 tolling start with the unwieldy design of the tolls to apply only to one part of a single cross-Lake Washington travel corridor (something created by politics). Thus the value of the program is diminished by the distortion of traffic demand bulging onto “free” I-90 rather than reshaping itself within a larger, rational cross-lake pricing plan that would embrace both SR 520 and I-90.
Secondly, the fixed and inflexible pricing tiers in the time-of-day toll schedule adopted by the state Transportation Commission and the Legislature are a weak substitute for truly variable market pricing. This frustrates the full power of off-peak discounting to maximize the use of SR 520’s all-day capacity. Only with flexible, fluctuating market pricing, tuned directly to traffic demand levels on the roads, will tolls achieve their full ability to make roads efficient.
Nonetheless, the SR 520 program is a big stride in the right direction.
What can we see in the early results? And what can we still expect to learn as drivers make their own weightings of time, distance, and money and settle into new patterns with a tolled SR 520 in the traffic management mix? Think of the big diversion question this way: It’s not most importantly about the avoidable downside of diversion to I-90, the byproduct of shortsighted politics. It’s about the effect pricing should have to divert, that is to reshape, SR 520 traffic in different patterns across the day on SR 520 itself. Success will improve the economic and social return on investment represented on SR 520 itself, a major achievement if it happens.
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