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The big news so far is no surprise. The peak period price ($3.50 a crossing at the five hours daily at the height of customary travel) has dramatically shaved peak volumes on SR 520 at the same time it has handed remaining SR 520 drivers the benefit of slashing their time in traffic. The number of drivers who judged the savings in time worth the toll has climbed day after day since tolling began. Last Thursday and Friday mornings’ (Jan. 5 and 6) eastbound traffic volumes on SR 520 were at about 75 percent of pre-toll levels, yet traffic continued to speed along, a transformation of the old SR 520 traffic experience.
By Thursday evening’s peak period, westbound traffic at one point came very near to the typical pre-tolling experience, yet continued to move at good speeds, reflecting another well-documented traffic fact: Very modest easing of traffic volumes can turn clogged highways back to reasonable speeds. .
Less happily, off-peak traffic seemed, on the early experience, to have sustained a very large reduction in volume, dramatically and disproportionately reduced from pre-tolling experience. The off-peak price ($2.25 for one evening and four midday hours) seemed not sufficiently discounted (especially considering that in these hours the alternative on I-90 features no price and no congestion) to draw the traffic to the SR 520 Bridge that it easily should handle.
This suggests a hypothesis that the SR 520 off-peak price should be lower: More people would use the SR 520 bridge, rather than choosing, for many of them, a longer gas-guzzling detour over I-90. With greater volume at a lower price, midday revenue from the SR 520 Bridge could actually be higher. With true variable pricing, this issue would be solving itself.
By late in the first week, however, the midday numbers seemed to be showing a somewhat better trend. Early in the week the noontime traffic volume on SR 520 was well below half of pre-tolling experience and the graphing of volume across the midday hours resembled a deep ravine. But as the week ended, that noontime number was slightly over 50 percent of the pre-toll volume, still too low, but the graph line of volume drawn across midday between the peaks began to resemble a more attractive gentle swale.
Data for the shoulder periods (just before and after the peak hours) is very interesting. On SR 520, the price is lower (at $2.20) before 7 a.m. and after 9 a.m. (and for the afternoon, before 3 p.m. and after 6 p.m.). On I-90, drive times are faster (a lower price in congestion) in the shoulder periods. The evidence is that the shoulders are starting to see proportionally heavier use. That's exactly what should be expected in light of the fact that so much peak period traffic actually is made up of drivers and vehicles not rigidly tied to peak period commuting. But how strong or lasting the trend will be remains to be seen.
All of this early data falls against this important overview. Week one showed not just a shift in route and time travel patterns, but an appreciable drop in overall cross-lake vehicle traffic when SR 520, I-90, and SR 522 north around the lake are combined. WSDOT has put out a typical pre-tolling benchmark of about 280,000 cross-lake trips each day: 101,000 of those on SR 520, 138,000 on I-90, and 41,000 on SR 522. Against the benchmark slice of 101,000 for SR 520, last Tuesday 48,000 of those trips were missing from SR 520, and about 11,000 extra trips showed up on I-90 and SR 522. By Thursday, the meltage against the benchmark on SR 520 was down to 42,000 and the uptick on I-90 and SR 522 was up to about 25,000. So, even as traffic by Thursday was moving towards a new equilibrium, about 6 percent of the total crossing pre-tolling volume estimate couldn’t conveniently be accounted for on the other two routes.
Sorting out that early riddle will bring some of the most important information about the SR 520 program. As time passes, some of the missing cross-lake trips may reappear on the roads. Some may not cross the lake at all: a shopping trip closer to home! Some may move into virtual space: perhaps a worker will shift to a day a week of teleworking.
But an important clue to look for as soon as tomorrow (Jan. 10) is Metro Transit’s first report on how many new bus riders, including on Sound Transit express buses, showed up last week. Park-and-ride lots were said to be filling earlier, and buses were reported to be fuller than usual. New bus riders saved travel time in peak periods from an uncongested SR 520, just like the toll payers, but they did so by paying a bus fare, still a discount from the toll, and many of them they may also have saved parking costs at their destinations.
An appreciable gain in shared-vehicle ridership — not only on Metro and Sound Transit buses but also on private mass transit like the Microsoft Connector — would be a powerful gain for efficiency on the highway system. If the transit statistics reveal signs of that gain, it will underscore what many have long been convinced of: the significant latent power of transit service on SR 520 to make an ever-larger contribution to an efficient regional transportation system.
That neatly sets up a special perspective on one of the largest transportation planning issues now facing the region: What will the final plan look like for completing the SR 520 replacement program on the westside connecting from the lake bridge itself to Seattle and I-5? Will that plan adequately support the most effective long-term future use of transit on that route across the lake? That’s a critical next step in the discussion.
Here’s a clue: It’s not about light rail on SR 520, a terribly suited option for moving large numbers of people among the dispersed residential and job locations east and west that SR 520 quite literally bridges. Rather it’s about designing a complete infrastructure investment for SR 520 and its connection to I-5 and elsewhere that furthers the potential for tomorrow’s modern, flexible transit suited to our economic geography. And it's also about taking advantage, as future transit will, of emerging transportation technology.
A future smart bus likely will look and operate as little like today’s transit coach as a smartphone resembles a hardwired rotary-dialed telephone. Tomorrow’s transit fleet will be far less dominated by rubber-tire buses, although they will still be important. What we will come to think of as transit will also see vast and convenient expansions of powerful commuting tools foreshadowed by the Microsoft Connector and King County’s nationally admired vanpools.
And many of tomorrow’s transit users will first park their electric cars at a park-and-ride lot, where they will choose from an array of conveyances for the rest of their trip to a worksites. These are the springboards for visioning the future power and use of transit on SR 520. SR 520 must be fashioned from end-to-end to anticipate a big role for that coming transit transformation.
Tolling shows we can put SR 520 up to speed. Fitting the rest of the package for SR 520’s future to make the most of that potential is the next big hurdle.
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