Release – Thursday, December 18, 2025. (Click on image to enlarge).
PENNSYLVANIA – PennDOT has announced plans to designate U.S. Route 15 as Interstate 99 from Williamsport to the New York state line, with construction starting in spring 2026 and ending in fall 2027. The project includes signage upgrades and safety improvements, and aims to boost regional connectivity, economic growth and freight efficiency.
This project is significant because it transforms a key transportation corridor into a federally designated interstate, unlocking long-term benefits for safety, mobility, and economic development across north-central Pennsylvania. By upgrading U.S. Route 15 to I-99, PennDOT ensures the route meets modern design and weight-limit standards, which protects infrastructure and improves freight compliance. The designation also strengthens regional connectivity by linking major highways like I-80 and I-86, making travel more efficient for both commercial and personal vehicles. Ultimately, this investment supports local communities by attracting business growth, enhancing logistics, and improving overall roadway clarity and consistency.
For many years, PennDOT has made steady and long-term investments to modernize and transform U.S. 15 from a two-lane road between the City of Williamsport and the New York state line into a four-lane limited-access highway that meets Interstate standards. This final project will designate U.S. 15 as Interstate 99 (I-99) between I-180 interchange in the City of Williamsport in Lycoming County, and the New York state line in Tioga County. Designating U.S. 15 as I-99 will:Â
- Improve highway consistency and driver clarity. The route will be part of a continuous, signed Interstate corridor from Bedford to the New York border, making navigation simpler for both freight and passenger traffic.
- Enhance economic opportunity. Interstate designation promotes regional commerce by strengthening north–south connections to I-80 and I-86, encouraging business investment and growth throughout north-central Pennsylvania.
- Strengthen freight movement safety and compliance. Converting the route to Interstate status aligns it with federal weight-limit rules and modern design expectations, protecting pavement and bridge assets and ensuring fair, consistent permit enforcement statewide.
The department is in the final stage of seeking Federal Highway Administration (FHWA) approval to designate this roadway section as I-99. If approved, the current U.S. 15 between the City of Williamsport in Lycoming County, and the New York state border in Tioga County, will become I-99.
In November 2025, the department put out for bid a project which will upgrade the roadway signage along the 62-mile-long corridor in 2026. The project includes:
- Trailblazing signage along the Route 220 corridor from the I-80/I-99 Interchange near Bellefonte to I-180 in Williamsport along the Route 220 corridor.
- I-99 signing will be added to the current U.S. 15 corridor from I-180 to the New York state line.
- While the signs are being upgraded, three sign structures will also be upgraded as part of the project.
- Additionally, the Four Mile Road intersection with U.S. 15 Northbound above the Trout Run interchange will be closed to enhance safety on the corridor and meet federal requirements.
What is a trailblazing sign?
A trailblazing sign is a directional sign along a road that that directs motorists towards the desired route.
Why will there be trailblazing signage along Route 220 between I-80 and I-180?
With the establishing of I-99 north of Williamsport, a gap will remain between Bellefonte and Williamsport, requiring trailblazing signage to guide motorists between the completed sections of I-99. To address this, PennDOT will install trailblazing signs along Route 220 and I-80, ensuring clear directional guidance. This strategic approach will enhance regional connectivity and ensure motorists can easily navigate the new interstate designation.
Additional Project Information
The designation of I-99 will be a major change for companies that hold annual over-dimension hauling permits. Currently on U.S. 15, hauling permits can be issued for divisible loads of certain commodities up to 95,000 pounds. After designation as an interstate, per federal law, the maximum weight will be reduced to 80,000 pounds for divisible loads if there is no federal exemption for the commodity.
Impacts to Hauling Industry
- In accordance with federal law, once designated as I-99, the weight restriction will be reduced to 80,000 pounds for divisible loads.
- Divisible overweight permits will no longer allow travel on the designated section.
- Milk haulers are permitted under federal law to operate overweight on interstates including the future I-99 corridor.
- Haulers will be required to comply with the weight limits or reroute using alternate, approved state routes under their current Annual Network permits.
- After the designation is finalized, the Automated Permit Routing and Analysis System (APRAS) will prevent the issuance of new divisible overweight permits for this corridor.
- Permits for non-divisible oversize or overweight loads will continue to be issued and remain valid for travel along I-99.
Designation History and Background
Over the past four decades, PennDOT has made steady and long-term investments to modernize and transform U.S. 15 from a two-lane road between Williamsport and the New York border into a four-lane limited-access highway that that meets Interstate standards.
Beginning in the 1970s, PennDOT advanced a series of construction projects to replace outdated two-lane sections of U.S. 15, with a new four-lane, limited-access highway, and modern interchanges.
These coordinated projects, delivered in partnership with the Federal Highway Administration, have created a continuous, high-speed, limited-access corridor through north central Pennsylvania that enhances regional connectivity, freight movement, and economic development.
This section of U.S. 15 was included in the 1995 National Highway System Designation Act, which congress officially designated Corridor 9 as Interstate 99.
Link to project: https://shorturl.at/FHR16
