Paw Paw Tunnel Scaling Project

A rockslide covers the towpath near Paw Paw Tunnel.
This image shows a rock slide in early 2013 before repairs were made to the towpath near the northern (downstream) entrance of the tunnel. The current scaling and repair project is one to prevent rock slides like this in the future.


The Paw Paw Tunnel is currently open. Phase 2 of construction began spring 2019. During construction, both portals of the tunnel will remain open and flaggers will be stationed to control traffic. Visitors should expect some delays.

Frequently Asked Questions

When will the project begin and end?

Construction began on the Paw Paw Tunnel project in June of 2017. Construction and area closures were expected to last through fall of 2017, but the timeline has been changed. Phase 1 of the project, which addressed the most urgent sections of the deteriorating rock slope, has been completed. Due to the availability of additional funds, however, the park will begin Phase 2 to address additional hazards downstream of the newly completed section. This will provide long-term safe passage through this stretch of towpath. The National Park Service is doing everything possible to minimize closure time and impacts to visitors.

What is the need for the project?

Loose rock above the towpath at the “cut” and north portal (downstream entrance to the tunnel) presents potential safety hazards to visitors. This rock also threatens to damage the boardwalk section of the towpath. This project provides for visitor safety from rock fall as well as protection for the boardwalk/towpath.

What does the project include?

The project includes “scaling” or removing loose and unstable rock and debris from above the towpath/boardwalk in the “cut” approaching the north tunnel portal. Additionally, rock will be “pinned” in place to provide further stability and long-term protection. Rock scaling and pinning has occurred in this area before. The project also includes temporarily storing rock debris on the berm side of the Canal for future removal. To provide thru-access for bicyclists during the project, a trail will be opened using an old logging road on the berm side of the Canal upstream of the south tunnel portal. A temporary “bridge” will be installed across the Canal prism that connects with an abandoned logging road that provides a gentler grade to the top of Tunnel Hill. This temporary by-pass then connects with the existing Tunnel Hill Trail. The existing Tunnel Hill Trail will remain open during the project but for safety reasons, cyclists will be required to dismount and walk their bikes across the mountain using the signed bypass trail detour.

To facilitate the work, construction equipment staging will require closing a section of the Paw Paw Tunnel picnic area parking lot. Additionally, temporary delays on the towpath approaching the south portal should be expected as work crews and equipment move to/from the work site. Work crews will use the tunnel to gain access to the site.

What is the history of the Paw Paw Tunnel?

The Paw Paw Tunnel is one of the most significant engineering features on the Canal. To save building six miles of canal along the river, the C&O Canal company decided to construct a tunnel through a steep topographic ridge now called Tunnel Hill. When work began on the tunnel in 1836, the builders estimated the project would be complete within two years. The tunnel ultimately required 14 years to complete due to labor issues and violence, funding shortfalls, work stoppages, and the challenges of digging a 3,118-foot tunnel through the hard, loose shale. The tunnel opened in October 1850 with rock slides continuing to be a challenge throughout the tunnel’s history.

View of the southern entrance and boardwalk leading to Paw Paw Tunnel
This portion of the towpath (northern tunnel entrance and boardwalk) will be closed for the duration of repairs. There will be detours for thru-bikers and hikers, as well as limited access to the tunnel's interior.

Monica Larcom | NPS

How will this project benefit park visitors?

Visitor safety will be improved by removing loose rock and debris from above the towpath and by stabilizing the remaining rock to reduce potential for future rock fall. This work will also protect the boardwalk section of the towpath from potential rock fall.

How will this project impact natural and cultural resources?

The project helps protect the north tunnel portal stone and brickwork along with the towpath itself. The temporary canal prism crossing upstream from the south tunnel portal will also be designed to minimize impacts to the wetland species and function. The temporary crossing will be removed and restored once the project is complete.

What is the park doing to protect resources during the project?

National Park Service resource protection experts will be monitoring the stone and brickwork in the tunnel, along with contractor’s operations and visitor safety during the project with the goal of safely protecting this unique cultural resource and the environment surrounding the project. Every project undertaken by the National Park Service is conducted in compliance with the National Environmental Protection Act (NEPA), the National Historic Preservation Act (NHPA), and other regulations.

How do I visit while thru-passage of the tunnel is closed?

Visitors will be able to access a substantial portion of the tunnel entering through the south/upstream portal throughout the project. Long distance Canal hikers and bikers will continue to have access either across the existing Tunnel Hill Trail (hikers) or using a temporary bypass connecting the towpath to an old logging road across the canal prism, which leads back to the Tunnel Hill and the existing trail (bikers and hikers).

How much does the project cost?

The project costs just over $750,000.00 and is funded by the National Park Service’s National Recreation Fee Program.

Who can I contact if I have further questions or concerns regarding the project?

Park Headquarter at 301-739-4200
A map showing the elevation change and length of the detour.
A graph and map showing the detour route and elevation change.

Andrew Landsman | NPS

Bike Detour Route Info

How long is the bike detour route? How steep is it?

The Tunnel Hill Trail bike detour route is approximately a mile and a half in length with an elevation change of 375 feet. From the upstream (parking lot) end, the detour begins by crossing the canal prism and climbs 0.63 miles to the top (or about one foot of rise per nine feet of distance). On the downstream (construction) end, the detour begins where the Tunnel Hill Trail meets the towpath near mile marker 155 and climbs 0.82 miles to the top (one foot of rise per 11.5 feet of distance).

Cyclists are reminded that they are required to dismount along the detour.

What else should I know about the detour?

Wear sturdy shoes that have good traction. Carry and drink lots of water during ascent and descent. Plan for the detour route taking between one and a half to two and a half hours depending on your load, fitness level, and pace.
Paw Paw Tunnel closure detour map using alternate routes
This map shows the construction and closure area, as well as detour routs for bikers and hikers.

Joe Reed | NPS

Last updated: August 9, 2019

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1850 Dual Highway, Suite 100
Hagerstown, MD 21740



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