In 2017, C-TRAN buses began using the shoulder of State Route 14 as part of the region’s first Bus on Shoulder corridor. Buses are allowed to use the outside shoulder of SR 14 between Southeast 164th Avenue and Interstate 205 during periods of heavy traffic congestion.

C-TRAN passengers have enjoyed faster travel times since Bus on Shoulder was put into practice on SR 14. In 2020, C-TRAN and the Washington State Department of Transportation are bringing Bus on Shoulder to a second major corridor: Interstate 5.

The I-5 Bus on Shoulder corridor is expected to launch in late summer 2020. Here are some frequently asked questions:

Download the Bus on Shoulder flyer. ( pdf)

How will Bus on Shoulder work on I-5?

On I-5, buses will be permitted to use the shoulder from 99th Street to the Interstate Bridge, southbound only. Unlike SR 14, buses on I-5 will not use the outside (right) shoulder of the freeway, due to potential conflicts with numerous off-ramps and on-ramps in the right lanes of I-5. Instead, buses will use the inside (left) shoulder to bypass traffic during periods of heavy congestion.

Isn’t that dangerous?

There are several limitations to when a bus is allowed to use the shoulder. The overall speed of traffic must be less than 35 mph, and the bus is only allowed to go up to 15 mph faster than other traffic – bus only to a maximum speed of 35 mph.

What about emergency vehicles?

Priority for shoulder use is always given to emergency vehicles or stalls and breakdowns. If another vehicle is in the shoulder because of an emergency, buses are required to merge back into the regular travel lanes.

Does it work?

C-TRAN routes that use the SR 14 Bus on Shoulder corridor have seen improved travel times since it began in 2017. Bus on Shoulder has also been successfully used in other parts of the country for decades.

When does it start on I-5?

Construction will happen during summer 2020, with driver training to follow soon after. The I-5 Bus on Shoulder corridor is expected to be fully implemented by September.

Does that mean I can drive my car on the shoulder, too?

No. Please don’t.

Which bus routes will benefit from this?

Several C-TRAN Express routes will be able to use the I-5 Bus on Shoulder lane heading south in the morning, including Routes 105, 134, 157, 190 and 199. Routes 164, 65 and 41 already use the SR 14 Bus on Shoulder corridor.

Will I-5 look any different?

A little. Southbound I-5 will be paved and restriped to accommodate the Bus on Shoulder lane, and signs will be placed along the freeway noting that shoulder use is for authorized transit vehicles only. Signs will also warn motorists when buses will be merging back into traffic at the end of the Bus on Shoulder corridor.

What about I-205?

There aren’t currently plans for permanent Bus on Shoulder lanes on Interstate 205. However, temporary Bus on Shoulder lanes will be set up on the Glenn Jackson Bridge during a separate Interstate Bridge trunnion replacement project in September 2020. That project is expected to close the entire northbound span of the Interstate Bridge for nine days and cause widespread traffic impacts across the region.

Where can I find more info?

Check out WSDOT’s I-5 Bus on Shoulder project page here: https://www.wsdot.wa.gov/projects/i5/southbound-bus-shoulder/home

Existing SR 14 Bus on Shoulder corridor:

Bus on Shoulder Map1