In early May, we will be adding new safety restrictions for large vehicles travelling through Pioneer Square. Vehicles weighing more than 10,000 pounds will no longer be allowed to park or drive in the lane closest to the sidewalks on First Ave in Pioneer Square due to concerns about the underground road support structures.
A quick history lesson
As you probably know if you’ve taken a tour underneath Seattle’s historical Pioneer Square district, many of the sidewalks in this part of town are built on top of empty spaces called areaways dating back to when the streets were rebuilt after the Great Seattle Fire of 1889 burned down 25 city blocks.
Residents decided to rebuild in the same location. New buildings were built over those that had been damaged by the fire, one to two stories above the original elevation.
As a result, many of the sidewalks in the area, especially along First Avenue, are built on top of empty spaces that date back to when the street was rebuilt. Over time, many of these areaways were turned into basements and cellars for buildings in Pioneer Square while others are still empty space.
Today, the weight of Pioneer Square roads and sidewalks are still being held up by support walls right under the outer edge of the sidewalk.
Underground support walls hold up the weight of cars and people above
Many of these street support walls were built from brick, rubble, and mortar over 100 years ago. These underground walls were not designed to support the weight of today’s large trucks and buses or to meet modern earthquake safety standards.
We have been monitoring the condition of underground areaways and street support walls for many years. Recently, when the SR 99 Viaduct closed and several bus routes moved onto First Ave, we conducted a new comprehensive analysis in order to identify safe locations for new bus stops. This led us to find new structural vulnerabilities which we had not identified before.
We found that the street support walls were all safe to support the weight of normal cars, but in some cases could not continue to hold the weight of large trucks and buses parking and driving next to the curb.
New rules for large vehicles on First Ave to keep everyone safe
In order to ensure the safety and integrity of the road, we need to add new safety restrictions for large vehicles travelling through Pioneer Square. Vehicles weighing more than 10,000 pounds will no longer be allowed to park or drive in the lane closest to the sidewalks on First Ave between Marion St and Railroad Way S.
This means that commercial load zones will be relocated and large trucks will need to park on another street. It also means large vehicles will not be able use the right turn lane at some intersections.
There is no change to for the rules about normal sized cars. The new rules will take effect as soon as we install new weight-limit signs. This could be as soon as Monday, May 6.
Pioneer Square roads are still completely safe
Don’t worry! You can (and should) still visit the neighborhood. It’s one of the oldest and most vibrant neighborhoods in Seattle.
Our engineers routinely monitor underground areaways and street support walls and are confident that the streets and sidewalks are safe to use, as long as large vehicles over 10,000 pounds remain in the inside lanes.
We’re also completely confident that the Pioneer Square sidewalks are safe for everyday activities (such as walking, sidewalk dining, and moving furniture). We’ve also checked to make sure that the tours underneath the sidewalks are completely safe too.
What’s the repair plan?
The first step is to conduct a thorough inspection of every underground areaway and road support wall in Pioneer Square.
We’ll be working with local businesses over the coming months to assess the condition of underground support walls throughout Pioneer Square and to install monitoring equipment.
We have also identified safe areas to relocate commercial load zones which are not near these kinds of underground areaways and support walls. This will likely result in additional weight restrictions and changes to commercial vehicle load zone locations throughout Pioneer Square this summer.
We’re committed to doing everything possible to keep you informed. In partnership with the Alliance for Pioneer Square and other City departments like the Office of Economic Development, we will work closely with the neighborhood to provide ongoing information about the safety assessment and repair work.
We will be talking to the community about these potential locations and will respond to feedback with clear, concise and thoughtful answers on whether their suggestions are viable. Our goal is to provide adjacent businesses and residents with accurate and timely information as we move forward to implement safety.