O41 Site
Site overview
The O41 site is located at the corner of North Point Drive and Belmont Street, near the West End Bridge in Pittsburgh. It is one of the key sites along the tunnel route, serving as the underground connection point where the Saw Mill Run Branch Tunnel will connect to the main Ohio River Tunnel, approximately 150 feet below ground.
Construction at O41 will include a large vertical shaft approximately 35 feet wide and 150 feet deep, along with connections to both tunnel segments and a relocated outfall.
Early site preparation, including the demolition of an existing building, was completed in early 2024.
Construction at O41 has been coordinated with Riverlife to support planning for future public access to the West End Bridge.
North Point Drive & Belmont Street, Pittsburgh Directions: Google Maps Apple Maps
Beneath the surface
Every construction site tells part of the story. Explore aerial site plans, underground cross sections, timelines, renderings, and project visuals to see how the Regional Tunnel System is being designed and built to protect our rivers for generations to come.
Underground Cross Section
Cross-section illustration of the Ohio River Tunnel facilities underneath the O41 site located near North Point Drive on the North Side. A relocated sewer connects to a regulator that directs overflow into a vertical drop shaft approximately 150 feet deep and 35 feet in diameter. The drop shaft is connected to the Saw Mill Run Tunnel, which crosses underneath the Ohio River. It also connects to the Ohio River Tunnel through an underground connector tunnel. Both the Saw Mill Run Tunnel and the connector tunnel are located about 150 feet below ground. The image also shows a tunnel vent location, a relocated sewer, and an outfall relocation. Surface buildings, bridges, streets, the Three Rivers Heritage Trail, trees, and subsurface soil and bedrock layers are displayed to illustrate the local context.
Aerial Site Plan
Aerial site plan showing the location of the Ohio River Tunnel (ORT) facilities underneath the O41 site at a parking lot off North Point Drive near the West End Bridge. The ORT is shown crossing beneath the site at approximately 150 feet below ground. A connector tunnel connects a regulator and a drop shaft to the ORT. The plan shows the Saw Mill Run Tunnel, which crosses underneath the Ohio River, also connecting to the shaft. The plan also identifies a tunnel vent, a relocated overflow sewer and a relocated outfall. Shaded areas indicate the limits of construction and locations of intermittent road closures, with local streets, parking lots, and trail providing context for the construction site location.
What to expect during construction
Nearby businesses will likely experience construction impacts, such as intermittent noise during shaft excavation, potential noise from authorized night work, and increased truck traffic during specific phases of the project.
ALCOSAN is committed to working with businesses to minimize disruption and will keep stakeholders informed of what to expect during each phase of the project.
Permitted work hours at this site will be:
General work hours*
- 6:00 a.m. to 8:00 p.m., Monday through Friday
- 7:00 a.m. to 8:00 p.m., Saturday and Sunday
*Impact-producing construction activities, such as pile driving and jackhammering, are limited to 8:00 a.m. to 6:00 p.m., Monday through Saturday. Controlled blasting activities are limited to 7:00 a.m. to 7:00 p.m., Monday through Friday, and 9:00 a.m. to 5:00 p.m. on Saturdays. Work hours exclude legal holidays; limited exceptions, including emergencies, may apply.
Extended hours for specific activities
Certain activities at the O41 site will occur outside of the general work hours. These include:
- Authorized underground work and support activities: Certain underground construction and support activities may occur during extended hours.
- Surface activities: Any authorized surface activities occurring during extended hours will be limited to on-site work.
What's happening at O41
Closures, public meetings and construction updates for the O41 site.
