RapidRide Corridor 1049 (Route 150)

Route 150 uses a queue jump in Tukwila. Photo by King County Metro.

This week is all RapidRide as we review the Candidate Corridors analyzed in Metro's recently published RapidRide Prioritization Plan.

King County Metro Corridor 1049, a potential RapidRide conversion of Route 150, was recently set as a Tier 1 priority corridor, expected to be constructed before 2039 after the current RapidRide projects are finished. Route 150 connects Kent to Seattle via Southcenter and currently averages around 4,000 weekday boardings. When it gets upgraded to RapidRide service, Metro expects a 60% ridership increase and a 22% travel time savings.

This line will be the first RapidRide line to use a freeway alignment. Currently the route follows I-5 and the SODO busway downtown. Because the busway is planned to be taken over by the West Seattle light rail line, it would need to use 4th Avenue South instead.

Metro's one-page summary of the candidate route.Alternatives Analysis

Currently Route 150 ends at downtown Seattle, Metro considered avoiding the freeway and truncating the route at Rainier Beach Station on Henderson. While that's not where most riders want to go, it would increase reliability, schedule adherence, and flexibility but might take slightly longer to downtown due to the transfer and because the 1 Line is not as direct as the freeway/busway. Riders could continue more reliably on Link but also connect to other lines such as the 7 (or RapidRide R by then) along Rainier.

Two alternative routings for the northern portion of the RapidRide corridor under consideration by Metro.

Metro had also considered truncating the line at either SODO or TIB stations. It rejected both potential termini because SODO is already quite close to downtown and TIBS both is too far out of the way and duplicating RapidRide F.

After the main alignment 1 was chosen some further adjustments were made.

• Change northern terminus to 3rd Avenue and Virginia Street from Seattle Convention Center.
• Adjusted current downtown service to use 3rd Ave instead of the existing 2nd and 4th Ave couplet.
• Delaying realigning from SODO busway onto 4th Ave S as suggested in Metro Connects instead continuing to use busway for now.
• Realign service in Tukwila to use 66th Ave S instead of existing 61st Ave S to increase reliability.

Delays and Improvements

Most delays are centered around I-405, on S 180th St (shown on map as SW 43rd), and around Kent Station.

The improvements would increase transit priority percentage of the route from 38% (including the hov lanes on i-5) to 58%. Though it appears that the suggested improvements would surprisingly ignore the high delay regions and instead add BAT lanes in areas that are easier to implement.

• In SODO: On 4th Ave add northbound bus/BAT lane between Spokane St and Edgar Martinez Drive S, and a southbound bus/BAT lane between S Holgate St and S Spokane St. . Most likely done after West Seattle Link impacts SODO busway.
• Tukwila: Adjust Andover Park W & Minkler Blvd signal reducing cycle time. The change to using 66th Ave S instead of 61st Ave S will slightly speed up travel times as well.
• North Kent industrial area: Adds northbound and southbound BAT lanes along long stretches of 68th Ave S
• Around Kent Station: Consolidate westbound right turn lanes on Washington Ave. Add eastbound queue jump at 4th Ave N.

Station Stops

Currently the average stop spacing is 1,600 feet or about one-third of a mile (excluding the freeway segment) and approximately 40% of stop pairs are less than a quarter-mile apart. The proposed station stops would increase the average spacing to 2,400 feet or half a mile. The much farther stop spacing makes this route the closest to Community Transit's Stride bus lines. The busiest stops would remain Kent Station, Andover Park W (Southcenter) and downtown Seattle.

Costs & Conclusion

Metro estimates that the total cost for the improvements would be approximately $61million dollars, with 45% for transit speed and reliability, 42% for new bus stations, 9% for charging infrastructure, and 3% for layover facilities.

Now the main question is whether to run it directly downtown or truncate it at Rainier Beach. Assuming the route heads downtown and the transit improvements are completed, Metro estimates there could be an impressive estimated net increase of 4,000 riders per weekday, a 60% increase from current ridership.