Cape Fear Memorial Bridge
The Port City's Green Monster
The Henrietta III river boat is made small by the large bridge behind it.
Without a doubt this is North Carolina's mightiest bridge. Its 408-foot polygonal Warren truss span is by far the longest in the state, beating the closest contender, the nearby Isabel Holmes Bridge, by nearly 100 feet. It is also one of the longest simple truss (non-cantilevered) spans in the Southeast. The towers lift the bridge 135 over the Cape Fear River, and are a visible part of Wilmington's rather humble skyline. At one time in its existence this giant carried four US highways between Brunswick and New Hanover counties. Today it marks the start of the US 76 expressway into Brunswick County, and is an important component of the region's transportation network.
By the time this bridge was constructed in 1969 engineers had "simplified" the designs of truss bridges. As opposed to "stitching" small beams together to make a larger, stronger structural member, these newer bridges used members that came as one piece from the foundry. Compare this bridge to Wilmington's 1911 6th Street Bridge to see what I mean. This modern reduction in complexity makes for a cheaper and easier-to-maintain design, but at the price of aesthetics. The Warren truss design seemed to displace all others around this time, likely due to its simpler design compared to others such as the Parker. Finally, all of the connections on this bridge are made using bolts instead of rivets. Bolts, in my opinion, have a crude, "temporary" look to them, and look even worse when they rust. Nevertheless, this is still a pretty interesting bridge to look at, especially from a distance. The elongated curved shape of the top chord gives it a semi-arched look. On shorter spans, polygonal Warren trusses have a more angular look to the top, but this bridge's length gives the main span its more streamlined shape, since the angles are so minute.
Of course, any aesthetics that this bridge possesses are merely unintentional; it was obviously designed to be purely functional. The railing, for example, is of the steel tube style that was common in NC before the advent of the Jersey barrier. In addition to being ugly, this railing style does not appear to be particularly strong. The tops of the towers, under which much of the lifting mechanism is concealed, are covered with corrugated steel, with absolutely no attention paid to visual appeal. Finally, the green color of the main span provides a rather unsightly contrast against the gray of the towers (the designer must have been color blind). Wilmington is one of the most beautiful cities in the state; it deserves a bridge painted uniformly, a bridge painted when it needs it. But as I have stated before, there is nothing more irksome to the NCDOT than a truss bridge.
The Wilmington approach to the bridge includes a partial cloverleaf interchange with Front Street, which becomes "Truck 421" south of the bridge. The interchange is used quite a lot by trucks heading to and coming from the Port of Wilmington. The ramp onto the bridge is a tight circular one that the trucks ascend rather slowly. Fortunately there is a pretty long merge lane between this ramp and the main span. Non-truck US 421 traffic makes it way onto or off the bridge at a signalized intersection with US 76, at the ends of the approaches. The longer approach spans near the lift span are steel stringers, while the shorter ones use prestressed concrete beams.
I'm not sure whether or not this bridge opens much in the 21st century, when the majority of the port facilities north of the bridge have been removed. The only vessel I saw in the near vicinity that would require its raising would be the U.S.S. North Carolina battleship, and its fighting days are over. There is a Coast Guard ship that docks at the wharf downtown, but this probably comes in during off-peak traffic hours. Its 60-foot or so clearance when closed is probably sufficient for most recreational boats. Nevertheless, this bridge causes traffic jams, mostly because it doesn't have enough lanes for two counties that have grown massively since 1969.
The steel grate deck of the main span dips and rises subtly, as if it's bowing underneath. Hopefully this is just a design quirk rather than actually bending of the metal. Like most of NC's truss bridges, it hasn't been well cared-for, though it's by far better than most. Most of the red you see in the pictures is the primer underneath the green paint rather than rust.
The Facts
- Year built: 1969
- Route Carried: US 76, 421, and Bus. 17 (formally US 17 & 74)
- Crosses: Cape Fear River
- Location: Wilmington, New Hanover County, NC
- Design: Vertical lift with polygonal Warren truss main span, and steel stringer and prestressed concrete approaches.
- Length of main span: 408 ft. Total length: 3033.3 ft.
- Inside width: 54 ft., four lanes
- Vertical clearance underneath: 135~ ft. raised, 60~ ft. closed.
- Average Daily Traffic: 46,000
- Sufficiency Rating: 35.8 out of 100
- National Bridge Inventory ID: 1290013
- Coordinates: 34°13'38.79"N, 77°57'6.41"W
Photos
- Left: the vertical lift span. Center: a distant view, showing some steel stringer approaches. Right: an oblique view.
- Left: Warren truss panels. Center: the underside, showing the see-through steel deck. Right: a bridge tower.
- A gusset place connection on the upper chord, showing the bridge's use of bolts instead of rivets.