scary in an unusual way is the Washington Crossing bridge. It spans PA - NJ, over the Delaware River, from Washington Crossing, PA to Washington Crossing, NJ.
The bridge was built in 1905, and its road deck is only 15 feet wide, meaning that lanes in each direction are only 7.5 feet wide. In addition, while the access road on the PA side is straight onto the bridge, on the NJ side it's nearly a 90° turn from the access road to the bridge. The 90° isn't too bad when going from PA into NJ, but when going from NJ to PA, you pretty much can't turn onto the bridge unless there is a break in the cars coming from PA.
Due to the narrowest of the road decks, even on bright sunny days, it's pretty rare to go the entire length of the bridge (@ 877 feet) without encountering a car coming in the opposite direction that stops due to concerns that they're going to side-swipe a car driving in the opposite direction. As such, backups frequently occur on the bridge due to cars stopping as the driver loses their nerve.
I believe the Delaware River Joint Toll Bridge Commission, which owns the bridge, issued Request for Proposals earlier this year for a consulting team, to start the environment review process, for the purpose of eventually designing and constructing a replacement bridge.