I-405 Express Lanes Successful, Necessary for I-405 BRT

ST Express bus enters the ETL lane at Bellevue (Image by author)

WSDOT's express toll lanes on I-405 opened in September 2015. Having recently passed the two-year mark, the Legislature may consider next year whether they should continue. At stake is not only the improved efficiencies of the managed lanes. As Peter Rogoff highlighted last week, an end to tolling would force a rethink of the Sound Transit BRT program that only makes sense if buses can move reliably in well-managed lanes. The loss of tolling revenues would also defer highway investments benefiting drivers.

By many measures, the lanes have been a success. At peak, each express lane carries more vehicles than each general-purpose lane. In some places, vehicle throughput in the tolled lanes is up to 30% greater than the regular lanes. Overall, the busiest parts of the corridor are now transporting 20% more vehicles, or 30% more people, than before. Pricing allows more people to travel with greater reliability and higher speeds than the congested GP lanes.

The lanes have been popular with drivers from the beginning. Politically, they were less favored at first. Improved operations, a strategic retreat on night and weekend tolling, and toll-funded investments at the north end, have made the lanes more popular.

Transit Performance: The lanes also deliver faster and more reliable transit performance. Metro travel times on I-405 have improved 15-29% in the PM peak, and 3-7% in AM peak. Community Transit times have improved 7% northbound, and are more reliable in both directions. In 2015, Community Transit added $2.6m in schedule maintenance costs on I-5 (added service hours so buses could arrive at their scheduled times). Community Transit has not needed to make similar investments in the more reliable I-405 corridor. The variability of travel times on I-5 remains twice that of I-405.

Sound Transit reports a +1% improvement in performance on I-405 routes, vs. a 6% deterioration on other routes in the same time. Ridership has increased 4%.

Vehicle Performance: Average vehicle speeds have increased 6-7mph in all the northbound general-purpose lanes and in the northbound general-purpose lanes between Bellevue and Bothell. Between Lynnwood and Bothell, southbound peak speeds are the same as before the ETL opened.

This WSDOT slide demonstrates the far greater efficiency of vehicle movement with ETL lanes vs comparable areas on I-5. Two ETL lanes on I-405 move three times as many vehicles as a HOV-2 lane on I-5.

Highway Investments: In April, WSDOT opened a peak shoulder lane northbound between SR 527 and I-5. It was an inexpensive project, just $11 million, relieving a chokepoint and significantly reducing congestion. Throughput improved 15% to 5,200 vehicles per peak hour, with improved speeds and reliability across all lanes. Toll rates fell, with far fewer drivers paying the highest tolls.

The peak shoulder lane was funded from toll revenues. With gas tax revenues fully committed until 2030, toll revenues become critical to funding more improvements in the corridor. WSDOT projects a cumulative $1 billion of toll revenues on I-405 by 2040 that must be invested back into the corridor.

Earlier this year, the Legislature authorized $5 million toward preliminary engineering for improvements on the north end of I-405. Adding an express lane in each direction north of Bothell, and partially rebuilding the interchange with SR 522, would cost about $450 million. With pay-as-you-go toll revenues alone, the added southbound lanes could open in 2027, and northbound in 2033. Both could open as early as 2024 with bonding or other revenue sources (a small gas tax increase may be considered by the Legislature in 2018).

What will the Legislature do?: The enabling legislation specifies the lanes must cover operating costs and operate at least 45 mph speed at least 90% of peak hours. The former requirement has been easily met. Over the first 21 months of operation, tolls yielded $38.6 million in revenue with operational costs of just $13.6 million.

The speed requirements is fulfilled in the 2-ETL lane sections and in the northbound 1-ETL section. All exceed 45 mph about 95% of peak hours. The southbound single-lane section, where AM peak demand exceeds the capacity of one ETL lane at $10, only exceeds 45% about 63% of the time. That pulls the average down to 85%, narrowly missing the Legislature's target, but much better than the 56% performance in the HOV-2 lanes before tolling.

Some lawmakers have made noises about ending express lane operations, a few even demanding that they be removed as soon as practicable. More seem content to defer the discussion to the next legislative session.

ST3 and I-405 BRT: The ST3 program commits $869 million to BRT services on I-405 between Lynnwood and Burien. The Board could spend more if WSDOT makes complementary investments. For instance, when WSDOT adds express lanes at the north end, Sound Transit could fund inline stations or direct access ramps. But as Sound Transit also warned in 2016, effective operation of BRT relies on WSDOT to maintain adequate speed and reliability of the I-405 express toll lane system.

Last week at a meeting of the I-405 Executive Advisory Group, Peter Rogoff spelled out the implications for I-405 BRT if the Legislature were to end the express lanes:

The question arises: if we do away with the potential to have high-capacity transit on 405, is Sound Transit even authorized to build the BRT project? I'm not authorized to just throw more express bus service on the street. I'm charged by law with providing high-capacity transit, transit that will move. And I think that needs to be a serious consideration as to any revisiting of the managed lane regime on 405. Because we would have to have a very rich conversation among our board members " [] We're not talking small amounts of money, we're talking north of 800 million dollars " [] We are working to make this happen by 2024. But if the traffic's not going to move, there will be no rapid in bus rapid transit, there will be no high in high capacity transit, and we would have to completely rethink the investment as a Board. So I hope to be able to communicate that to those that want to revisit the regime at this point because frankly our whole plans for the I-405 BRT are premised on the facts that the lane has got to move.

It's not just transit users who would regret if express lanes were converted to HOV-2. WSDOT modeling suggests a steep deterioration in traffic conditions across all lanes in the corridor, with extended ramp queues onto I-5. The revenue sources for corridor improvements would be removed, as travel demand from fast-growing South Snohomish County continues to grow.