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Construction to Impact Traffic on I-5

H Frame ConstructionCity Light is working to increase the electrical capacity and reliability to the Duwamish Valley with the H-Frame Replacement and Feeder Installation Project. This project will impact traffic on I-5 with intermittent ramp closures, lane closures, rolling slowdowns and traffic detours and surface street closures between the West Seattle Bridge and S 188th St as workers remove transmission cable currently spanning across the highway.

The construction work will occur during the hours of 9 p.m. to 5 a.m. on Sept. 7 (Sunday night into Monday morning) and Sept. 8 (Monday night into Tuesday morning).

City Light is replacing eight outdated H-Frame structures and cables that transmit electricity on high voltage lines across I-5 due to their age and increasing electricity demand. The project will improve system safety and increase electrical reliability for customers.

The traffic impacts and restrictions for this project are necessary for motorist and worker safety. Drivers are advised to carefully obey the direction of the on-site uniformed law enforcement Officers, follow traffic detours and consider using alternate routes during construction.

Several I-5 north- and south-bound on-ramps within the traffic impact area will be closed intermittently during hours of construction as well as surface street, exit and I-5 lane closures. Uniformed law enforcement officers will control traffic flow onto the interstate both Northbound and Southbound, and within the affected area.

H-Frame Traffic Map_Template_Final

Traffic advisory map for 9/7 and 9/8

Lane Closures

  • Traffic will be reduced to one lane on SB I-5 in the vicinity of Exits 158 (Boeing Access Road) & 157 (Martin Luther King Way S)
  • Traffic will be reduced to three lanes on NB I-5 in the vicinity of Exits 157 (Martin Luther King Way S) and 158 (Boeing Access Road)

Intermittently closed on-ramps:

  • S Columbian Way to I-5 SB
  • West Seattle Bridge to I-5 SB
  • Carlton Ave to I-5 SB
  • Interurban Ave to I-5 NB
  • Southcenter to I-5 NB
  • I-405 Carpool to I-5 NB
  • I-405 to I-5 NB
  • S 188th St to I-5 NB

Street Closures:

  • Southbound Martin Luther King Jr Way S/SR 900 at Boeing Access Road (follow detour)
  • Northbound Martin Luther King Jr Way S at S 129th St (follow detour)

On-Ramp Closures:

  • Boeing Access Road/Martin Luther King Jr Way S/Ryan Way S intersection to I-5 SB
  • Northbound Martin Luther King Jr Way S to I-5 NB

Exit Closures:

  • Northbound I-5 Exit 157 (to Martin Luther King Jr Way S/SR 900)
  • Southbound I-5 Exit 157 (to Martin Luther King Jr Way S/SR 900)
  • Northbound I-5 Exit 158 (to Boeing Access Road)

For more information about this and other City Light construction projects, please visit

About Seattle City Light

Seattle City Light is the 10th largest public electric utility in the United States. It has some of the lowest cost customer rates of any urban utility, providing reliable, renewable and environmentally responsible power to nearly 1 million Seattle area residents. City Light has been greenhouse gas neutral since 2005, the first electric utility in the nation to achieve that distinction.