I-5 Toll Conversion
WSDOT is currently conducting an I-5 master plan study. The primary focus for the Seattle metro area involves converting HOV lanes into express toll lanes. While the current study won't be finalized for another four years (until 2029), previous completed studies from 2010 to 2012 that provide a good starting point.
Existing HOV to Tolled Express LaneThe previous studies discussed converting the existing I-5 HOV lane to a tolled lane. However, between Northgate and downtown Seattle the (currently free) reversible express lanes complicates matters.
The previous I-5 Express Lanes Toll Study (2012) outlined in the first phase to toll the I-5 reversible (currently free) express lanes.
It'd be relatively simple as the toll conversion would only require adding electronic readers at one place just south of the NE 42 St ramp. The toll implementation would cost $13 million dollars (2012) or around $18 million dollars (2025) today.
Tolling Phases from I-5 (reversible) Express Lane Toll Study
Current and Planned I-5 HOV LanesThe second phase would then convert the existing I-5 HOV lane from Tacoma to downtown Seattle and from Northgate to Everett. This would be relatively easy to accomplish given the existing HOV lanes from Tacoma to Everett. The estimated cost from the study was $675 million (in 2012) dollars or around $939 million (in 2024) dollars.
The dotted section from Northgate to Lynnwood adds a second peak-direction only toll lane described more below.
Northgate to Lynnwood Second Peak-Direction Toll LaneCurrently the reversible express lanes from downtown Seattle to Northgate consists 3 lanes with 2 lanes merging into I-5 and 1 dropping off at the Northgate Transit Center. With the I-5 HOV to toll lane conversion there'd only be one toll lane from Northgate to Lynnwood. It'd be ideal if there were 2 tolled lanes in the peak-direction to maintain lane continuity.
Normal operations on the left with 1 toll lane, 3 general lanes and 1 shoulder; Peak-direction operations on the right with 2 toll lanes, 3 general lanes and no shoulder
While adding a movable barrier in the median would be ideal, it's impossible due to structures such as bridge piers in the way. Instead the dynamic lane assignment study (2012) proposed a second dynamic toll lane in the peak direction. The dynamic lane would convert the outer shoulder lane into a general lane during peak traffic periods.
Dynamic lanes in the peak direction are already used in some places such as northbound I-405 near Bothell (right side shoulder to general lane) or also at southbound I-5 near Mountlake Terrace (left/inner shoulder for bus only lane).
Tacoma to SeaTac/Tukwila Second Toll LaneVarious studies proposed for adding a second toll lane in both directions from Tacoma to SeaTac, Tukwila, or further north to Seattle near SODO.
Puget Sound Gateway Project Phases mapThe Puget Sound Gateway Project (SR-509 and SR-167) study called for adding an additional toll lane on I-5 from Tacoma to SeaTac ending at the new SR-509 extension.
SR 509 Phase 1
SR 509 Phase 2This would potentially happen after the SR-509 extension is built. The configuration of two express toll lanes would allow one express lane to continue onto the SR-509 while the other toll lane would continue onto I-5.
The previously mentioned I-5 Express Lanes Toll Study proposed adding the second toll lane on I-5 from Tacoma to SeaTac and then further north to Tukwila at I-405. The construction estimate was $501 million (in 2012) dollars or around $700 million (in 2024) dollars.
The I-405 from Tukwila via Renton to Bellevue project is currently adding toll lanes along I-405 from Renton to Bellevue. There are some existing HOV to HOV connections that could easily be converted for toll lane usage connecting the I-405 and I-5 HOV/toll lanes. The I-5 southbound to I-405 northbound has an existing direct HOV to HOV rampunderpass. The I-405 southbound to I-5 northbound has a partial HOV ramp but merges into general traffic on I-5. The I-5 northbound to I-405 northbound and vice versa direction does not have any HOV connections.
I-5 Second Express Toll Lane to SODO
Dynamic Lane Assignment Map
Other plans in the Dynamic Lane Assignment (2012) call for extending the second toll lanes from Tacoma even further north to SODO district in Seattle. (Shown in solid orange above)
A I-5 direct access project was proposed in the Roads and Transit Package (2007). The HOV direct access ramp would go from the center I-5 HOV lane to South Industrial Way. The second HOV/toll lane would drop at Industrial Way connecting with the SODO busway. Originally the plan involved extending the SODO busway south of Spokane Street, but the SODO busway will be taken over by the West Seattle Link Extension. A future Industrial Way connection can still easily connect to 4th Ave S which potentially will have bus lanes.
Costs and Benefits - EverettBelow shows a chart of the costs adjusted to 2024 dollars and a suggested adjusted amount given construction cost overruns post covid. The I-5 single HOV lane to toll conversion has more recent estimates from the PSRC draft regional plan (2022).
| Project | Costs |
| Airport Way Direct Access Ramp | $83 million (2008) => $121 million (2024) adj $181 million (2024 w/ cost increases) |
| Reversible Express Toll Conversion | $128 million (2024) adj $192 million (2024 w/ cost increases) |
| I-5 Managed Lanes: US 2 (Everett) to I-405 (Tukwila) (northern half) | $356,928,335 (2022) ~= $178 million for half |
| Total | ~$500 million (2024) |
Converting the I-5 HOV lanes from Everett and Seattle's reversible express lane portion cost in total around 500 million dollars. This would allow a quick ST Express bus running in toll lanes for around 40 minutes. In comparison the proposed Everett Link Extension would take 60 minutes to travel from Everett to Westlake.
| Mode | Time |
| ST Express 510 without traffic | 41 minutes (5th & Pine) |
| Link Light Rail Line 1 | 60 minutes (Westlake Station) |
| ST Express 510 with traffic | 60~70 minutes |
| ====================== | |
| ST Express 510 without traffic | 48 minutes (5th & Jackson) |
| Link Light Rail Line 1 | 65 minutes (CID Station) |
| Sounder N | 59 minutes (King Station) |
| ST Express 510 with traffic | 75~85 minutes (5th & Jackson) |
The next couple I-5 improvements projects described, while feasible, are unlikely to happen due to greater technical difficulty or lower benefits. The projects discussed are addressing the reversible express lane, extending the I-5 HOV/toll lanes further north and south, and connecting the I-5 HOV lanes with new direct access ramps in Tacoma.
Converting Reversible Express Lane to BidirectionalCurrently the reversible express lanes in Seattle provide a bit of unbalanced capacity. They are useful in the peak direction but can leave the opposite direction with insufficient lanes. During the PM peak when the reversible lanes are configured northbound the southbound direction encounters heavy traffic.
I-5 Reversible Express Lane map annotated with one permanent southbound lane in blue1~3 reversible lanes in purple, northbound entrance/exits in orange
One proposal is to convert one lane on the reversible express lane to permanently southbound from NE 65th Street to downtown. This would relieve congestion southbound at the I-5 Ship Canal Bridge. Unfortunately it comes at the expense of closing some ramps.
The downtown Seattle Pine/Pike St ramps as well as the Stewart ramps would only continue southbound off ramps because of the permanent southbound lane. The Columbia/Cherry St and 42nd St ramps would continue working in the peak direction since they enter from the east. The Lake City Way entrance/exit connects on the west but is north of NE 65th Street.
HOV Lanes to Olympia and MarysvilleCurrently the I-5 HOV lanes span from Tacoma via Seattle to Everett. There's some HOV extensions (and potentially easy toll conversion) both south and north.
I-5 Mounts Road to Thorne Lane project map
I-5 Marine View to SR 529 project mapWSDOT is currently extending the HOV lanes. on I-5 from Tacoma south to JBLM as part of the I-5 Mounts Road to Thorne Lane (2023) project. The HOV lanes are planned in future projects to eventually reach Olympia.
In 2024, WSDOT just recently opened a northbound HOV lane on I-5 from Everett to Marysville as part of the I-5 NB Marine View Drive to SR 529 (2022) project. A future southbound HOV lane will complete the HOV connection between Everett and Marysville.
Missing HOV Ramps in Tacoma
HOV system map in Puget Sound Region by WSDOT The HOV lanes on I-5 in the Tacoma area are missing direct access ramps, forcing buses and carpool cars to weave through general lane traffic to get on and off the freeway. South of Seattle there is only the Federal Way direct access ramps. In contrast north of Seattle there exists the Mountlake Terrace Freeway Station, Lynnwood direct access ramps, Ash Way Park & Ride, South Everett (Median) Freeway Station, and Everett direct access ramps to Broadway.
aFreeway BRT Alternative Map from Tacoma DEISThe Federal Way to Tacoma High Capacity Transit Corridor Study (2014) freeway BRT alternative shown above and the Sound Transit Long Range Plan Appendix A (2014) outlined possible I-5 direct access ramps and inline flyer stations around Tacoma.
Google map of Tacoma area annotated with possible Direct Access Ramps and Flyer StationsThe Tacoma Dome Link initial study proposed adding at South Federal Way Station and Fife Station inline flyer freeway stations. Assuming a Tacoma Dome Link extension is built, those two inline freeway stations would be pretty duplicative. A Tacoma Dome direct access ramp on the other hand would still be pretty useful for an express bus from Seattle.
E. J Street HOV/Transit Direct Access Interchange - From the center HOV lanes, the direct access ramps are configured beneath I5 and through a short tunnel at E. J Street to E. 25th Street and the Tacoma Dome Station (from the Federal Way Tacoma Way HCT Study)Costs and Benefits - Tacoma
The I-5 HOV to toll conversion projects from Seattle to Tacoma as well as direct access ramps would cost around $800 million dollars. The I-5 hov to toll conversion estimates are again from the PSRC draft regional plan (2022).
| Project | Costs |
| Airport Way Direct Access Ramp | $83 million (2008) => $121 million (2024) adj $181 million (2024 w/ cost increases) |
| I-5 Managed Lanes: US 2 (Everett) to I-405 (Tukwila) (southern half) | $356,928,335 (2022) / 2 for southern half ~= $178 million |
| I-5 Managed Lanes: I-405 (Tukwila) to Pierce/ King County Line | $255,112,240 (2022) |
| I-5 Managed Lanes: Pierce/ King County Line to SR 16 (Tacoma) | $32,032,030 (2022) |
| J Street HOV Direct Access Ramp | ~$150 million dollars (ballpark estimate from $600 million of building all four freeway stations) |
| Total | ~$800 million |
The Tacoma Dome direct access ramp, combined with previously described tolling of I-5, would allow a quick 45 minute travel time from Tacoma Dome to CID on the ST express route 590. In comparison the proposed Tacoma Dome Link would take 67 minutes to travel from Tacoma Dome to CID. While spending $800 million dollars would be a bit excessive, typically WSDOT would cover the toll conversion while Sound Transit only needs to build the direct access ramps.
| Mode | Estimated Travel Time Tacoma Dome to CID |
| ST 590 (no traffic) | 45 minutes (4th Ave S & Jackson St) |
| Sounder South | 62 minutes (King Street) |
| Link Light Rail Line 1 | 67 minutes (CID Station) |
| ST 590 (with traffic) | ~60 minutes (4th Ave S & Jackson St) |
Some further extensions south are possible as well. From the Sound Transit Long Range Plan, a direct access ramp was proposed for Lakewood P&R. The HOV ramp would likely be built offset from SR 512 to the south near or connecting to S Tacoma Way. This ramp would allow bus routes ST 574 and ST 594 from Lakewood P&R and heading north on I-5 to easily enter and exit the HOV lanes.
ConclusionThe I-5 tolling of HOV lanes has some moderate potential to speed up ST Express buses. Even with Link light rail extended to Everett and Tacoma, ST Express buses could offer a faster travel time as an intercity bus service for traveling between farther city pairs. The Everett to Seattle I-5 segments already have all of the direct access ramps built, but the Seattle to Northgate segment is complicated with the reversible express lanes. On the other hand, the Tacoma to Seattle I-5 segment can easily have all-day bidirectional toll lanes, but lacks direct access ramps both at Airport Way and at Tacoma Dome.
Citations- Roads and Transit Package (2007)
- I-5 Express Lanes Toll Feasibility Study (2011)
- Dynamic Lane Assignment (2012)
- Puget Sound Gateway Project (2013)
- Sound Transit Long Range Plan Appendix A (2014)
- Federal Way to Tacoma High Capacity Transit Corridor Study (2014)
- Draft Regional Transportation Plan (2022)
- I-5 NB Marine View Drive to SR 529 (2022)
- I-5 Mounts Road to Thorne Lane (2023)
- I-5 Master Plan (2022-2029)