Evening traffic backs up across the river into Shepherdtown on September 12.
Update September 12 2023: Turn restrictions added to several local roads.
The Route 340 Rockfall Remediation project detour (see related story) is expected to create spillover traffic throughout Jefferson County and the surrounding region as drivers find their own directions around the traffic backups along the official detour route (map above).
The alternative route to the north through Boonsboro, Sharpsburg and Shepherdtown is not designed to accomodate heavy traffic volumes or large trucks. This route also passes through several downtowns, with quick changes from 50 MPH to 25 MPH speed limits (images below). In Maryland, the speeding fines start at $80 (and are doubled in school zones). In West Virginia, the speeding fines start at $100. Both jurisdictions also assign points to your drivers license for speeding violations.
Route 40 Alt through Boonsboro was a state-of-the-art highway when it was paved a century ago — now it’s a low-speed (25 MPH limit) local road through a small downtown village. 
There is no left-turn arrow at the signal at Route 40 Alt westbound to head south towards Sharpsburg and Shepherdstown, so even a slight increase in traffic will likely trigger an extended bottleneck throughout downtown Boonsboro. 
The speed limit through both Sharpsburg (above) and Boonsboro is 25 MPH. 
Backups at the stop signs south of the bridge in Shepherdstown are a regular occurrence, even in the middle of the day with typical traffic volume. The speed limit in Shepherdstown is 25 MPH and traffic can be blocked by Norfolk & Southern trains several times a day.
Drivers can avoid the Route 340 detour by using Interstates 70 & 81 to bypass to the north, connecting to Route 9 (via Route 45) or Route 51 (Middleway Pike) to access Jefferson County from the west. To the south, Routes 15 & 7 offer another bypass, connecting to Route 340 to access Jefferson County from the south. These extended bypass routes have their own rush hour traffic patterns, but these patterns are consistent and the roads are designed for heavier traffic flow.
UPDATE: Traffic Restrictions In Clarke County
The Clarke County Sheriff has announced turn restrictions on Shepherds Mill Road (Route 612) and Castleman Road (Route 603) to be in effect for the duration of the Route 340 closure in Harpers Ferry:
- NO LEFT TURNS – 6 to 9 a.m. daily – from U.S. 340 South onto Shepherds Mill Road (Rt. 612).
- NO RIGHT TURNS – 3 to 6 p.m. daily – from Va. 7 onto Shepherds Mill Road (Rt. 612).
- NO THRU-TRAFFIC at any time on Castleman Road (Rt. 603) between Shepherds Mill Road and Va. 7.
UPDATE: Traffic Restrictions in Loudoun County
The Loudoun County Sheriff will be enforcing traffic restrictions on Sagle Road. Some online navigation services were suggesting Sagle Road in Loudoun County as a connection between Harpers Ferry Road and Route 9, bypassing the traffic signal. There are signs at both ends of the road that clearly indicate local traffic only, and for a good reason: the surface is not paved and the road is barely 15 feet wide — not really enough room for two cars to pass in opposite directions.
The project website (US340HarpersFerry.com) will not provide traffic updates. WVDOH representatives suggested the WV511.org website as a resource for drivers looking for current traffic information during the project. The Observer will post any project updates we receive from WVDOH on our website at WeAreTheObserver.com. You can sign up for The Observer’s email updates here.
By Steve Pearson