Tanana River Pipeline Suspension Bridge - Big Delta, Alaska
Posted by: 
BruceS
N 64° 09.381 W 145° 50.900
6W E 556013 N 7114943
Suspension bridge used to span the Tanana River by the Trans-Alaska Pipeline in Big Delta, Alaska.
Waymark Code: WMB9AX
Location: Alaska, United States
Date Posted: 04/22/2011
Views: 3
The span between the tower is 1,200 feet and this bridge is the second longest of the 13 major bridges along the 800 mile pipeline length. A suspension bridge was used at this site due to the cost and danger of other crossing techniques. A more traditional truss bridge would have required footings to be place directly in the river with a strong current and would have been more costly to construct and maintain. Due to the strong current it was determined that burying the pipeline under the river as used for other river crossings would not be safe as the scouring action of the river could uncover the pipe and expose it to the rocks moved by the river when in flood stage.
The bridge employs for 2-3/4 inch cables in each of its main cables and wind cables of 2 5/8 inch diameter on each side. The bridge employs nearly 25,000 feet of cable in its construction.
Due to the soil conditions along the Tanana River the towers and anchors are set on pilings driver 68 feet in depth into the ground. The towers each rest on 32 piles and the main cable anchors rest on 81 piles. More than 18,000 feet of pilings were used in the construction.
The bridge is designed to withstand a magnitude 7.5 scale earthquake and also to withstand a wind speed in excess of 100 mph.
About 155 pipeline miles south another suspension bridge spanning the Tazlina River is about 600 feet longer and is the longest bridge on the pipeline.
Usage: Automobile
Length: 1200 feet
Date Completed: Not listed
WWW: Not listed
|
Visit Instructions:
Log your find with the picture of the bridge that you like. No gpsr required in the photo...different seasons and lighting for the pictures is what will be the goal.