The following article about the three major bridges along the proposed ore haul route was prepared for ASAH by Bill Ward of Delta Junction. The Johnson, Gerstle and Robertson River bridges, built during World War II, are functionally at the end of their useful lives. The in-depth article explores the known issues as well as possible solutions. These solutions should be thoroughly vetted in order to protect the traveling public and safeguard our state dollars.
Key points are:
• The Alaska Department of Transportation and Public Facilities (AKDOT&PF) determined during their 2018 bridge inspections that these three bridges are either in poor, unstable condition because of substandard substructures and limited load-carrying capacity, or they are due for immediate replacement.
• Given these bridges were determined to be unstable and in critical need of replacement in 2018, the impact of the proposed ore haul could very well lead to catastrophic failure.
• The bridge replacements cannot be completed before the proposed 2024 start of the ore hauling. AKDOT&PF has begun design for two of the replacements, but the actual replacements are currently unfunded. ASAH estimates the total cost for this work is on the order of $250M.
Facts, Findings, and Conclusions regarding the present and future status of legacy bridges
There are three long span bridges on the Alaska Highway between Delta Junction and Tok that were built during WWII. The Alaska Department of Transportation and Public Facilities (AKDOT&PF) has determined these three bridges to be either in poor condition because of substandard substructures and limited load capacity, or they are due for immediate replacement. See Map of bridges (1088 downloads )
- Gerstle River Bridge #0520, Milepost 1393 AK Hwy, Length: 1820 feet
- Johnson River Bridge #0518, Milepost 1380 AK Hwy, Length: 975 feet
- Robertson River Bridge #0509, Milepost 1353 AK Hwy, Length: 1980 feet
Information and inspection data on these bridges has been gathered from public sources, primarily from the website: https://bridgereports.com/ak/ and various AKDOT&PF website sources. The latest bridge inspection data publicly available is from 2018, five years ago, so that data may not represent the current status of these bridges. Typically, inspections are carried out every two years. A recent RFP was issued to perform passive seismic surveys on specific pier foundations on the Gerstle and Johnson Bridge with results due by 2/28/2023. Those reports may assist in bridge scour ratings or evaluating substructure stability. Refer to Attachment I (1237 downloads )
2018 National Bridge Inventory Inspection Findings
Definitions:
Bridge Scour is a term used by the US Dept. of Transportation-Federal Highway Administration (FHWA) to determine the degree of material being eroded (scoured) from around the bridge abutments and piers.
Scour Critical Bridges receive a code description with a ranking from (8)-stable to (0)-bridge failure. Refer to Attachment A (1708 downloads )
- The Gerstle River Bridge is Scour Critical (3) and the foundations are determined to be unstable. Refer to Attachment B (1060 downloads )
- The Johnson River Bridge is in Poor (4) condition and Scour Critical (3) with the foundations determined to be unstable. Refer to Attachment C (1423 downloads )
- The Robertson River Bridge is recommended for replacement because of substandard load carrying capacity or substantial bridge roadway geometry. Refer to Attachment D (1104 downloads )
The AKDOT&PF has indicated that the Johnson and Gerstle bridges are scheduled for replacement due to inadequate load carrying capacity, being functionally obsolete, and requiring extensive repairs. Refer to Attachment E (1115 downloads )
The latest Alaska Statewide Transportation Improvement Program (STIP) (11/21/22 amendment 5) project & cost estimate puts the cost of replacing the Johnson River Bridge alone at over 40 million dollars. In light of inflationary pressures and recent AKDOT&PF bid openings where the low bids were significantly higher than the engineer’s estimate, it’s possible these three bridge replacement costs could exceed 250 million dollars. Refer to Attachment F (1199 downloads )
FINDINGS OF FACT
FINDING A: Using traffic counts from the 2018 inspection reports, the daily number of truck crossings on these bridges is 91 units. If we include the projected number of truck combinations Kinross will have on the road, the following deductions can be made:
- The number of truck trips across these bridges will increase from 91 truck crossings/day to 287 truck crossings/day, a 315% increase.
- The total weight of the trucks crossing the bridges will increase from an estimated 6 million pounds per day to 28.3 million pounds per day, a 475% increase.
FINDING B: Every vehicle, and loaded trucks in particular, have a static and dynamic stress impact on the structural integrity and life of a bridge with each crossing. With the additional Kinross trucks that numerical impact will be magnified by 315%. The moving dynamic stresses create a rolling wave force on a bridge caused by a loaded truck and has a direct impact on bridge structure and foundations; the heavier the truck the greater the dynamic stress impact will be. It’s like a wave of water being pushed ahead of a ship. With Kinross trucks weighing 165,000 lbs., that’s double the normal impact of other trucks with up to 100 loaded trucks per day going on 24/7/365. If these bridges and substructures are already considered unstable by formal inspection reports and already have some load capacity restrictions, then the overwhelming impact of a Kinross truck haul may very well lead to bridge failures. Refer to Attachment J (1048 downloads )
FINDING C: ASAH’s Freedom of Information Act (FOIA) request for AKDOT&PF’s response to Kinross’s request for approval of its ore haul was denied 11/28/22 leaving open the question about the matters of bridge inventory ratings factors as referenced in their denial. If the public is forced to rely on outdated 2018 reports, there is no way to know the actual condition or rate of decline of these bridges. The bridge ratings can’t get better, they can only get worse, and we, the traveling public, don’t know if we’re traveling on safe bridges or ones subject to catastrophic failure. Refer to Attachment G (703 downloads )
FINDING D: Unless and until the AKDOT&PF bridge design engineers and the FHWA can unequivocally guarantee that the truck ore haul operation proposed by Kinross/Contango will have no detrimental effect on any of the three bridges, then the company should be denied access in accordance with Alaska Statute 17 AAC 25.100a Road Closures and Restrictions. Refer to Attachment H (799 downloads )
FINDING E: AKDOT&PF has indicated that these three bridges are due for replacement. The Johnson Bridge is scheduled for design in 2023 and construction in the years beyond. Using the STIP estimates and projecting cost overruns, these three bridge replacements could cost 250 million dollars, in today’s money. Regardless of the critical need for replacement, there will be stiff competition for STIP funding for other projects around the state. Given the remote nature and (by assumption) low public use, it’s very likely that replacing these bridges will be delayed years into the future. Even though it isn’t well known, much of Interior Alaska’s commerce, industry supply, and most of Fairbanks’ fresh food comes up the Alcan Highway and across these bridges. Also of great importance, these bridges are a vital transportation link for Tok and eastern Alaska residents to travel to Fairbanks for shopping and medical care. Refer to Attachment E (1115 downloads ) and Attachment F (1199 downloads )
CONCLUSIONS
The Gerstle, Johnson, and Robertson Bridges are part of the vital critical infrastructure of Alaska. Even though their age and condition may require replacement in the future, that process will take time and a considerable amount of funding. It is in the State’s best interest, and for the public’s benefit, to rigorously maintain these bridges to minimize the dynamic stress impacts caused by existing truck traffic and to extend the bridges’ economic life as long as possible. If allowed, the Kinross ore haul could very well accelerate the destructive impacts on the bridges and shorten their life. It’s also possible the ore haul could lead to the catastrophic failure of any one of them. Any AKDOT&PF Maintenance & Operations attempts to shore up or reinforce these bridges wouldn’t be cost effective or guarantee safety.
The risk is too great and under no circumstances is the Kinross ore haul in the public’s or State of Alaska’s best interest, especially since this ore haul is designed solely for shareholder profits of a foreign-owned company, and it does nothing to improve the quality of life for Alaskans or our infrastructure. The Kinross/Contango Manh Choh mine operations plan will do everything to reduce their costs, including using Alaska’s public highways as their mine-to-mill industrial haul road. The Kinross ore haul will pay or contribute nothing for the industrial use of the highway beyond paying highway fuel taxes and that revenue is microscopic compared to the damage the highway ore haul will cause.
The best solution for all parties is for Kinross/Contango to build a processing mill on-site or near the mine. The critical Legacy Bridge issue and all the other corridor concerns would be solved by that action. If the State of Alaska allows the ore haul to proceed but prohibits the Kinross truck configuration from using these three bridges with cause per 17 AAC 25.100a, then Kinross could choose to use the alternate route of Tok Cut-off Hwy #1 to Gakona Junction and then back up the Richardson Hwy #4. An investigation of those road surfaces, bridges, and traffic conditions may find that this route has its own perils and may also be deemed unsafe and inappropriate. Refer to Attachment H (799 downloads )
This document was prepared on behalf of Advocates for Safe Alaska Highways (ASAH) and others. For questions or information please contact Bill D Ward, Delta Junction, 907-803-3043 or bdwardak@gmail.com