(
Archived Bridge Hunter;
Bridge Hunter; no Historic Bridges;
pghbridges;
Satellite)
The bridge is 4,544' (1,385m) long with a 750' (227m) main span. [BridgeHunter]
This is the northern part of the bridge that goes over the navigation channel in the Ohio River.
Turning around, we see the rest of the bridge to the south because these views are on a ramp that goes down to Neville Island.
 |
pghbridges
"TYPE OF CONSTRUCTION / DESIGN: steel through tied arch; deck girder approach spans and ramps"
This source specifies a length of 725' (221m) for the main span and it has a clearance of 68' (21m)
"The crossing at Neville Island was the final link in the 180-mile north-south Interstate 79."
"The main channel crossing is one of the few places where bicycles are allowed on an Interstate highway. Signs direct cyclists to stay on the shoulder. They are permitted only between the Glenfield (19) and Neville Island (18) exits." |
pghbridges has a separate page for the Back Channel Bridge, i.e. the southern part.
The back channel bridge gained worldwide notoriety in the winter of 1977. Only five months after a gala ribbon-cutting which opened the final link in the 180-mile Interstate 79, a 10-foot long crack in one of the bridge girders was noticed by a tow boat operator. The $50 million bridge was closed for three months while PennDOT made repairs.
The defects were blamed on an electroslag welding process. Other bridges built during this time, including the 1976 Birmingham Bridge over the Monongahela River, were also checked and repaired. The Federal Highway Administration prohibited further use of electroslag welding on all bridge tension members. Over the past 20 years, conventional processes, such as submerged arc welding and shielded metal arc welding, were used instead. A new technique Narrow Gap Improved Electroslag Welding (NGI-ESW) has been developed.
From the FHWA website: "Electroslag welding is a process used to join thick steel plates in a vertical position. A consumable guide bar is placed between the plates. This bar guides an electrode wire. The plates are joined together by melting the plate edges, the guide bar, and the electrode wire in a pool of molten metal shielded by a flux bath (slag). The flux is kept molten due to electrical resistance to the current passing through the slag."
"With NGI-ESW, the magnitude of electric current applied is much greater than in conventional electroslag welding, and the gap between the plates, and hence the amount of molten material used, is relatively small. This results in a higher welding speed."
More hairline cracks were found in the Neville Island girders in 1999. $1.8 million was budgeted for those repairs. Holes are bored at the ends of the cracks to relieve the strain and prevent the cracks from spreading further.
Pittsburgh Press Roto article, June 5, 1977:
view page - "The Award-Winning Bridge That Failed" by William Allan Jr.
.jpg)
.jpeg)
.jpeg)
