Washington considers conversion of Seattle tidal lanes to HOT lanes

Interstate 5 within Seattle has just over 7 miles of tidal flow (reversible) lanes. The lanes operate southbound towards Seattle in the morning (5am-11am) and northbound in the afternoon (noon-11pm) (but are closed to reduce noise for residents near the Ship Canal during the night). The lanes operate from downtown Seattle to Northgate Mall. They are not tolled, but do have an HOV lane.

Map of I-5 express lanes in Seattle

The Seattle Times is reporting that the State of Washington is considering converting all of the express lanes to HOT lanes. This would mean that vehicles could only access the lanes if there was occupancy of 3+ or a toll is paid. It would require a law change and the report indicated that:

“Tolls might begin in five years, and vary from $1.55 midday to $4.30 in the morning peak or $5.50 in afternoon peak, in 2016 dollars.”

The intention is to raise revenue to support maintenance of the highway, which is apparently urgently needed, but the obvious impact will be to increase traffic on the I-5 parallel non-express lanes (which are only different in that they are part of the main highway and the interchanges along it).

The intention is that any toll would be collected using a DSRC type system, which can easily be implemented. What it shows is that the revenue squeeze for transport authorities is causing them to think how they may better use precious scarce road space, manage it effectively and have users pay for the capital tied up in such infrastructure. This HOT lane conversion is unlike all others which have involved conversions from HOV lanes.

Washington State will need to get this considered carefully, in part to ensure the costs of collection and enforcement can be optimised, but also the economic effects of the diversion onto the uncharged lanes (and the long run benefits of optimised maintenance and a long term programme to improve levels of service on the I-5). However, it will be good for other states to notice this innovative approach, and for the Federal Government to positively support it.