Segmenting tolls on I-405 could be a bait and switch

Dec 15, 2017

*Note: this blog is part 3 of a short blog series on the University of Minnesota I-405 toll lane study released on 12/13/17. Read part 1 here and part 2 here.

In a recent report analyzing the performance of failing I-405 Express Toll Lanes (ETLs), several recommendations were provided to improve speeds so that the state can keep the toll lanes, rather than terminate them as promised.

One of the recommendations is to segment tolling and restripe for more access points so people can merge in and out more often. This means that tolls would change depending on what segment of the corridor you’re in. The report claims this open access strategy on certain parts of the ETL facility, in conjunction with quickly changing tolls, “could improve traffic flow and throughput.”

While applying toll rates to individual segments may work well where systems are more developed and sufficient general purpose capacity exists, segmenting in this corridor will further hurt drivers who cannot afford the tolls. With no guarantee of a price for downstream segments when entering an upstream segment, drivers will be forced to come to a stop in the ETLs to merge into highly-congested general purpose lanes.

Additionally, the open access strategy may very well work if toll lane speeds are equal to or slower than general purpose lane speeds, but this would also mean that traffic congestion would worsen in the general purpose lanes as more people transfer out of the toll lanes. If, on the other hand, toll lane speeds are faster than general purpose lane speeds, then there may be increased friction due to braking as people from faster toll lanes try merge into slower general purpose lanes before they cross into a new segment with a higher toll rate. Crash rates would rise while general purpose lane performance further deteriorates.

The current model “allows motorists to ‘lock in’ one corridor-long toll rate upon entering the facility…for simplicity and ease-of-use for motorists.” Segmenting tolls in this corridor would make it more difficult for motorists, not only because of the challenges an open access strategy could create, but also because it would likely lead trips to be more expensive overall. To make matters even more complicated, drivers simply won’t know what they are buying.

It would be like ordering a steak at a restaurant for $30, and about 1/3 into your meal, being told it’s now $100. People would have maybe a minute to do math and make split financial decisions while driving. The problem could be compounded further, as the Washington State Department of Transportation (WSDOT) is planning to extend the lanes to Renton, creating multiple segments where drivers may have to add up even more prices together as they drive.

A less reliable trip

The initial goal of ETLs, according to WSDOT, was to provide a more reliable trip. Segmenting tolls runs counter to this goal as the trip would become more unreliable for the driver. People would not know either the final cost of their trip or how long that trip might take, as a high price might force them into general purpose traffic half-way into their commute. If they merge back into general purpose lanes, they will still have paid to enter the toll lanes, but without the benefit of a reliable and complete trip.

The only way the driver can have total assurance of reliability is to have zero price sensitivity – in other words – commit to using the toll lanes regardless of how much the price may change. This is exactly what having a more responsive toll algorithm and increased toll cap, two other recommendations in the report, are trying to avoid. The “success” of the toll lanes depends on pricing people out, not in.

Why didn’t transportation officials choose to segment tolls in the first place? One might think it is because the toll lanes were difficult to sell to begin with. House Bill 1382, which authorized the toll lane program, was concurred on in the House of Representative 51-44 at final passage. Transportation officials made big promises about improved general purpose lane speeds and reassured drivers that the toll they chose to pay upon entrance into the toll lanes would not change.

Patty Rubstello, assistant secretary of transportation for urban mobility and access, said that segmenting tolls will require “much more investigation and conversation.”

Ultimately, most of the “solutions” in the study are about providing congestion relief in the ETLs – leaving the rest of us wondering when congestion relief will become a priority for everyone else.