Bitterroot Bridges Coalition web page
Maclay Bridge is an old single lane bridge over the Bitterroot River west of Missoula. According to Historical Research Associates in a report for the South Avenue bridge project, in 1953 the bridge’s main truss section (called a Parker truss, pictured above) was salvaged from an old Blackfoot River bridge crossing and erected at the Maclay site. It was intended to replace part of a previous bridge that washed out in 1948. The old bridge now consists of 3 piers in the river and 4 sections: the old Parker truss installed in 1953, one pony truss (a short connecting section), and two reinforced concrete spans erected in 1964, with many repairs over the years as parts wore out, washed out or failed. It is classified as functionally obsolete and fracture critical by the Montana Department of Transportation (MDT) and Missoula County officials.
Besides being a single lane bridge with accident clusters at the nearly 90 degree turn on the west end and a 45 degree turn on the east, it has structural and stability problems due to its age, wear and tear from high traffic volume, unknown foundations, vulnerability to floods, and deterioration. National traffic standards for a bridge of this type are for no more than 100 cars per day, yet it often handles over 2,000 cars per day. It has a very low sufficiency rating of 27.3 out of 100 and 98.3% of all Montana off-system bridges rate higher than it. In addition to its approaches violating State safety standards, the bridge is the site of many deaths and accidents. It’s old and its many parts are worn out including the deck of the bridge in which holes have sporadically appeared through which the river could be seen down below (see following photos), requiring frequent repairs Due to the low clearance of the bridge, it is vulnerable to being washed out in the next 100 year flood event.
Due to its bad configuration over the river, the old bridge has caused ongoing environmental damage to the river channel and banks, including unnatural channel constriction and scour, bank erosion and sediment deposition. It is likely a legal liability to the County and an “attractive nuisance” due to the many diving and swimming accidents it invites.
Two separate environmental studies completed by the State and County of bridge alternatives both recommended construction of a new bridge at a South Avenue river crossing over other options, including rehabilitating the old bridge. The 1994 and 2013 studies confirmed through detailed analyses that a new bridge would not create a bypass or attract more traffic. Instead, the new bridge would provide a shorter and much more efficient route that would reduce traffic impacts on 5 streets in the Target Range neighborhood (studies show North Ave., Clements, Woodlawn, Humble and River Pines Rd. would see reduced traffic with a South Avenue bridge). See following air photo. Traffic studies confirm most of the traffic crossing Maclay Bridge comes from or goes to South Avenue.
Maclay Bridge is currently closed to school buses due to the weight limit placed on it by MDT and the unsafe conditions, therefore school children who live west of the river must ride to and from school by a much longer route every day. (See Missoulian article).
Emergency vehicles such as fire trucks are severely restricted in crossing the bridge which limits response times to fires and medical emergencies west of the river.
Missoula County Commissioners voted unanimously in 2013 to ask the MDT to use Federal Gas Tax funds to replace the old single lane bridge with a new 2 lane bridge that would meet current and future needs and at a better site at South Avenue. They signed a formal project agreement in 2014. In 2015, the Commissioners again passed a unanimous resolution reaffirming commitment to the project. All commissioners since 1994 except Dave Strohmaier have supported the project.
Unfortunately, Mr. Strohmaier as a newcomer in 2016 and apparently without having read the studies, displayed bias against the scientific reports done to that date and favored instead an opposition group, as reported and criticized by the Missoulian newspaper (click on the highlighted text for the link). See also this Missoulian article that reported on Strohmaier’s behavior.
MDT and FHWA informed Strohmaier that the county will lose the $12.5 to $14 million funds already allocated and would have to pay back $1 million spent to date if the Commissioners abandon the project. In addition, MDT and FHWA have made it very clear that they will not pay for rehab of the old Maclay Bridge for many legitimate regulatory, safety, environmental, and financial reasons. In addition HDR Engineering strongly defended its environmental and engineering studies (which are in addition to--and agree with--the 1994 and 2013 studies) in its rebuttal to Strohmaier. As a result, Strohmaier and the other commissioners revised their stance and now appear to be allowing the project to proceed (https://missoulian.com/opinion/columnists/next-steps-for-south-avenue-bridge/article_75807f5b-e123-576c-9005-644f922e848a.html).
The South Avenue bridge project is a County-wide issue that all taxpayers should be concerned about. Clearly it would better serve the County and save taxpayer’s money if Federal gas tax dollars were used to build a new 2 lane bridge in a better location instead of County taxpayers having to reimburse the State over $1 million spent so far and then pay County dollars to fix up an old decrepit single lane bridge in a lousy location. All County taxpayers INCLUDING Missoula city residents will pay through increased property taxes if the Commissioners don't proceed with the South Avenue project. Please email or phone the commissioners and let them know your thoughts.
On January 26, 2024, Maclay Bridge was closed indefinitely at the direction of Montana Department of Transportation bridge engineers because of the risk of failure of critical bridge components, namely many of the stringers–steel beams that support the bridge deck–are rotten, corroded and at risk of failing. This is based on the report of a field inspection by independent qualified bridge engineers that was done in June 2023. The state’s engineering review of that inspection report and their own calculations of the bridge’s capacity to carry loads came up with a capacity of "zero" which meant that the bridge is not reliable or safe for any type of traffic, including foot and bicycle.
MDT says it will take further engineering analysis to determine if repairs are feasible, but even if it's not a huge repair cost to strip the bridge deck and replace the stringers, the inspection showed there are other components of the old bridge that are also wearing out, and will need to be replaced. It's like an old car where you have to decide at what point more repairs are useless, you need to get rid of it and get a new one.
MDT and the County say that bridge dollars are in short supply and it’s doubtful it will be practical to put more money into an old failing structure instead of into a new improved two lane at South Avenue. The County has told HDR Engineering to review the inspection report and come up with an opinion if it can be repaired and if so, how much it might cost. Due to its steady deterioration, the old bridge has already been closed multiple times for repairs over the last few years, but this current situation appears to be the most serious. It is a major disruption to people traveling from the Big Flat area, requiring them to go far out of their way to travel into Missoula to work, shop, and take kids to school.
On February 16, 2024, HDR Engineering sent a temporary bridge repair plan to the County proposing a short term fix to the bridge until the bridge can be replaced. MDT has agreed to pay for this short term fix out of State funds. Here is part of HDR’s repair plan memo:
Once repairs started on March 20, the County work crew found that at least 8 stringers (long I-beams) supporting the deck of the trusses to be alarmingly corroded and has begun replacing them. Here are some examples of the extent of the rot (photos taken April 15, 2024 to now):
Meanwhile repairs continue starting again April 22 and are projected by the County to perhaps be completed by mid-May, with May 9 a target date barring unforeseen problems. Again the County stresses these repairs are temporary. Many other parts of the bridge were identified as problems by the 2023 MDT inspection report.
The following chart is a timeline of the South Ave. bridge project from 2015 to present. The South Ave. bridge project could start in 2026 if it is not blocked again by its opponents, Maclay Bridge Alliance:
Missoula County has set up a website called Missoula County Voice that has many bridge related links and a section of Questions and Answers to issues with the Maclay Bridge/South Avenue Bridge project that is quite comprehensive. You can access it here:
https://missoulacountyvoice.com/maclay-bridge-south-avenue-bridge/widgets/76474/faqs#12354
You can also follow the progress of the South Ave. bridge project and get involved in its design process, which started in 2015, at Montana Department of Transportation's website here:
https://www.mdt.mt.gov/pubinvolve/bitterrootriver/.
The state website also contains explanations and documents for the South Avenue Bridge project. The air photo map below depicts the proposed project.
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Who we are:
The Bitterroot Bridges Coalition is an incorporated non-profit organization of Missoula County residents who are responsible for this website. Our goal is to help the Missoula County Commissioners and the MDT identify and apply common sense solutions to the real problems at Maclay Bridge such as advancing the South Avenue bridge project and devising better management of public use of the lower Bitterroot river ecosystem.
We support a safe new attractive 2-lane bridge with a walkway at South Avenue that follows the scientific recommendations of Montana licensed engineers employed by MDT and the County to meet the needs of the county into the future and that addresses environmental and safety issues. We also support removal of the old bridge due to its unsafe condition, the many environmental problems it causes, and the need for restoration of the bed and banks of the river at that site.
For more information, contact us at our email address: Bitterrootbridges@gmail.com
Maclay Bridge video: You can also watch a video on MaclayBridge and the South Ave. bridge project done by MCAT, local public access tv, and available on youtube here:
https://www.youtube.com/watch?v=CwrdqRk0JZ8
"The problem with common sense is that it is not so common anymore." —Voltaire
- The following documents help explain the need for the South Avenue Bridge (SAB) project and removal of the old bridge. The official SAB project website is at:
https://www.mdt.mt.gov/pubinvolve/bitterrootriver/
1. Options for Maclay Bridge and reasons for its removal are detailed in a matrix done by HDR Engineering. The engineering analysis matrix is posted and can be downloaded from here:
https://www.mdt.mt.gov/pubinvolve/bitterrootriver/docs/Maclay-Bridge-Options-Evaluation.pdf
From the following matrix, which can be found at the above website, the Commissioners decided to accept the recommendation of Option 1 Remove Bridge:
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2. An expert licensed bridge engineer who lived in the area explained the folly and “red herring” status of rehabilitating Maclay Bridge in a letter to Commissioner Slotnick that was posted on the County’s website:
Merv Eriksson March 29, 2019
845 Wyoming, Suite 402
Missoula, MT 59801
Subject: Maclay Bridge/South Avenue Bridge
Dear Commissioner Slotnick,
I’ve tried to avoid getting involved with this issue since its recent re-emergence. Until 6 months ago, my wife and I lived on Riding Ring Road, near the east end of the proposed South Avenue Bridge. My wife and I enjoyed the peace and solitude of the area.
However, I have been a professional bridge engineer for almost 44 years. I’ve worked for the Minnesota Dept. of Transportation, the Federal Highway Administration, the US Forest Service and a Missoula bridge engineering firm. I’ve designed, or approved the designs, of more than four hundred bridge replacements or major rehabilitations. For the majority of those bridges I was employed by the transportation agency owning those bridges. Therefore, I was involved in determining if they should be repaired or replaced. I was the primary author of the publication Identifying and Preserving Historic Bridges. I know bridge management and historic bridge rehabilitation, and I know the history of the Maclay Bridge.
I avoided involvement because I didn’t believe that pouring more money into the existing Maclay Bridge could possibly ever survive as a viable option. I knew that FHWA could not put money into a substandard bridge and that private, County State and Federal specialists would strongly recommend replacement. And South Avenue was easily the best location. I knew that would be the case when we built our home in 2008.
With the answer so obvious, I didn’t want to alienate my friends and neighbors on South Avenue who had been panicked by the efforts of MBA. Actually, I never felt like it was a big deal. The improved access provided by the new bridge will offset the inconvenience of more traffic, provided speeds are kept down and South Avenue from Humble Street west is upgraded. It never occurred to me that a small group of largely well meaning, but narrowly focused citizens could so severely sidetrack a good project.
I was involved with two bridge rehabilitations using the superimposed arch method endorsed by the MBA. In both cases (Lucille Bridge in central Idaho and Hoyt Flats Bridge near Avery, Idaho) traffic volumes were very low and single lane bridges were appropriate for these Forest Service roads.
That is not the case at the Maclay Bridge. The current type and volume of traffic precludes the acceptability of a single lane bridge, and this will only worsen as the bridge ages. Without getting too technical, the existing bridge has many components, all of which are old and many are deteriorated. Reinforcing the truss still commits the County to continued maintenance. It’s like replacing the engine of an old Yugo. The engine may run well but the wheels could fall off next year.
There is always an environmental cost in building a new bridge. That doesn’t mean we stop building bridges. The environmental reviews and requirements of both State and Federal government entities mitigate those affects as much as is reasonable to expect. Building the new South Avenue Bridge will have far less negative environmental effect than leaving the existing, under-spanned Maclay bridge in place.
The Maclay Bridge most certainly does not have exceptional historic significance and what historic integrity it has retained after having been moved and frequently repaired, would largely be lost by the imposition of the arch in the rehabilitation. I don’t think anyone has a love for this bridge, other than as a red herring to prevent construction of the new South Avenue Bridge.
Your decision on letting this project move forward should not be a hard decision. The County either allows the MDT and FHWA to construct a new bridge on South Avenue. Or, the County stops that action, repays $1.4 million to MDT and FHWA and tries to get by with a dysfunctional bridge across the Bitterroot River.
The Super-imposed Arch Rehabilitation option will never be constructed, since no responsible government entity will ever fund such a thing. FHWA cannot participate and MDT would want nothing to do with it. Missoula County residents will stand up at some point and refuse to fund such a waste of taxpayer money.
Although this decision should be an easy one for you, I’m sure the fallout will be difficult. The people actively involved with the Maclay Bridge Alliance feel that you owe them your allegiance and they will be very upset if you allow the project to continue. Difficult as it may be, I don’t think you have any real option but to move the project forward. Killing the project would be irresponsible.
Merv Eriksson
3. In a Missoulian Guest Editorial, former Commissioner Jean Curtiss states her views on the South Ave. bridge project:
I attended the Missoula County commissioners' meeting with the Montana Department of Transportation and Federal Highway Administration "to seek clarity" regarding the Maclay Bridge replacement project, in Helena, Feb. 13(2019).
Commissioner Nicole Rowley is very skilled at listening, asking clarifying questions and capturing what is said succinctly.
As a new commissioner, Josh Slotnick heard about the project and the process. He asked good questions and seems anxious to learn more from the consultants the county hired.
Commissioner Dave Strohmaier said more than once that he didn’t want to "get into the weeds" of the reports and continued to ask if the county has the authority to stop the South Avenue Bridge alternative, ignoring years of studies, and instead rehabilitate Maclay Bridge; if the federal dollars can be diverted to Maclay; if the county can require more environmental studies; and if the county has to pay back the million dollars if they don’t agree with the professionals.
I was the commissioner who nominated the bridge to be replaced using the Off-System Bridge Program; accepted the pre-Montana Environmental Policy Act/National Environmental Policy Act preliminary alternative for a new South Avenue bridge; signed the agreement to pay back the federal funds if the county stopped the project without a legitimate reason; with concurrence from both Maclay Bridge Alliance and Maclay Bridge Coalition (now named Bitterroot Bridges Coalition), hired HDR, a nationally recognized professional firm, to do the MEPA/NEPA analysis under state and federal rules and regulations to be reviewed by state and federal agencies; directed HDR to study the cost and scope of a rehab of Maclay Bridge in detail to meet the goals of the project related to safety, etc.
I have read the many years of data. The answers are in those "weeds" — decades of research, science and engineering.
Elected officials have tough decisions to make and should use the best information available. It may not be the popular decision but will be the right decision for the good of the whole. When all the independent experts, from many disciplines, come to the same conclusion from different angles, the decision to be made is pretty clear.
It is good that the commission plans to meet with HDR and the county engineer to "get into the weeds" and understand why they made the recommendation to build a new bridge rather than put bandages on the old one. An engineer's stamp on a project reflects their representation of facts, not political influence.
There is also a 12-month clock running that the commission was counseled is not like football. They can’t run the clock and say "oh I guess we aren’t building a bridge." They will be held to the payback clause.
When asked if the South Avenue Bridge is a done deal, Lynn Zanto, MDOT, said yes, unless a significant gap in the analysis of data is identified.
In summary, the professionals at the meeting said:
The environmental analysis is thorough and complete according to MEPA/NEPA.
If the county chooses to back out of this project, they will be required to pay back the money already spent — around $1 million.
The Off-System Bridge Program will not pay for fixing Maclay.
County taxpayers will have to pay for any additional environmental studies or fixing Maclay.
This is not a Target Range issue. Previous commissions took their responsibility seriously when they looked for sources of funds to relieve the local taxpayers of the burden of funding an expensive bridge replacement. The commission is elected to be good stewards of the tax dollars and the infrastructure. This project does both. You may contact the commission at bcc@missoulacounty.us.
Jean Curtiss
(Jean Curtiss is a former Missoula County commissioner)
4. On March 2, 2024, an expert licensed bridge engineer once again explained the folly of rehabilitating Maclay Bridge and the need for the South Avenue Bridge in a letter to the Commissioners and to MDT:
From: Merv Eriksson <mertolson@gmail.com>
Date: Sat, Mar 2, 2024 at 8:04 AM
Subject: Maclay Bridge Repair/Replacement
To: <bcc@missoulacounty.us>
Cc: <sstack@missoulacounty.us>, <edickson@missoulacounty.us>, <acullison@mt.gov>, <jweiger@mt.us>, <tgocksch@mt.gov>, <tlesnick@mt.gov>
To the Missoula County Commissioners,
I last wrote to the county in March of 2019 expressing my concern that Missoula County was considering a major repair of the Maclay Bridge. The thoughts I expressed in that letter, which I have attached, are even more true today.
Replacement of Maclay Bridge has been delayed several times for bureaucratic reasons. I urge you to move forward as soon as practical.
I first visited the bridge with Fred Crisp, County Bridge Engineer, in the late 1980’s. I coordinated grants and reviewed designs for the Forest Service Timber Bridge Initiative program. Some transportation agencies were replacing concrete bridge decks with timber to decrease dead loads and thereby increase live load capacity. Fred was considering applying for a grant to replace the MacLay Bridge deck. After looking at the bridge I had to inform Fred that the bridge would not be eligible since the alignment and bridge width did not meet any acceptable bridge geometric design standard. The west bridge approach would not even meet curve radius or roadway width requirements for a timber sale road. In addition, the bridge was in such poor condition, it made no sense to invest significant county or Federal resources.
Since writing my 2019 letter Maclay Bridge has been closed three times to repair serious safety issues. Two steels through truss spans were moved to this site in the early 1950’s. The east truss span failed within several years and was replaced with the current mix of bridge types Many of the original and current bridge elements are more than 100 years old.
The load capacity (11 tons) of this bridge is too low for a bridge which carries the amount and types of traffic Maclay Bridge carries. Load restricted bridges are generally safe for loads which do not significantly exceed the posted limit. However, the only thing that keeps heavier loads from crossing the bridge is the driver’s ability to read, understand and believe the load limit signs. Heavier loads can be expected to cross Maclay Bridge when it is reopened.
Maclay bridge is fracture and scour critical. Therefore, Underwater Inspections, Fracture Critical Inspections, Routine Bridge Inspections and Damage Inspections are required on a regular interval. When the cost of repeated repair design, repairs and construction inspection are added to the periodic inspection’s costs, Maclay bridge costs Missoula County well over $100,000 annually. That money could be spent much more wisely.
I know Maclay Bridge has been listed on the Historic Register, which I think is a very liberal interpretation of the Title 106 interpretation standards. I think you will see very clearly when the bridge is offered for adoption, no one is really interested in preserving this bridge. The only thing historic about this bridge is the thirty year battle to keep it in place, to prevent an increase in traffic volume on a short stretch of South Avenue!
If someone is injured when the bridge fails, the group opposed to closing the bridge will not be liable – but the citizens of Missoula County will be.
In my view, we are currently spending several thousand dollars per week perpetuating an undesirable situation that is a significant liability for the citizens of Missoula County. I urge you to permanently close the Maclay bridge and remove it as soon as possible, and expedite construction of the South Avenue Bridge as a replacement.
Merv Eriksson
5.) MDT’s January 25, 2024 closure notice for Maclay Bridge:
6.) Bitterroot Bridges Coalition letter to Commissioners regarding MBA’s plan to sample the rotten steel beams from the bridge repairs:
Dear Commissioners,
We very much appreciate the Missoula County Voice website which you launched two years ago to provide transparency and information. The Voice website recently posted a March 7 letter which had been sent to you by Fred Stewart, Maclay Bridge Alliance (MBA). In that letter, MBA asked you to allow Frank Muth, a consultant hired by MBA, to sample the steel stringers from Maclay Bridge during the repair work planned next month. MBA’s theory seems to be that if you allow them to take a “coupon” or small sample from one of the stringers and test it to see if it is steel rated A36, that this rating would cause MDT to assign a higher load limit for the bridge and move it from 11 tons to potentially 14 tons, high enough to allow school buses to once again cross it. Stewart states that his group is willing to pay for this testing.
We have a couple comments and observations to offer you on this request:
1.) MBA has long been on record as strongly opposed to building a safe new bridge at the South Avenue crossing. This crossing as you know has been identified in 3 different studies (1994, 2013, and most recently by HDR’s work) as by far the best and preferred crossing out of several alternative locations. However, MBA continues to deny the findings of those studies. MBA has effectively blocked and delayed the building of the new South Avenue bridge through insisting on more and more studies, by pitting neighbor against neighbor and making alarmist unsupported allegations that a new bridge would somehow create a bypass, threaten public safety, harm the environment, etc. All of these allegations have been considered in the 3 studies (1994, 2013, and HDR’s recent work) and refuted in detail. Yet MBA continues to throw up roadblocks including a claim that the old bridge is an historic feature that must be preserved. They have also hired a lawyer, threatened to file a lawsuit to block the South Avenue bridge project, and will undoubtedly seek to continue to delay the construction of a new safe reliable lower Bitterroot crossing, just as they have done since 1994.
MBA also continues to insist that Maclay Bridge can be repaired and at low costs to local taxpayers so that no new bridge at South Avenue is needed. This is despite the fact that the Federal and State agencies have stated multiple times that MBA is wrong on all of those points. Meanwhile the community suffers from the frequent repairs and closures of the old bridge (3 times in the last 4 years) and there continue to be dire MDT inspection reports that document the unsafe condition and deterioration of numerous parts of the old bridge. We wonder how long this latest repair will last before the old bridge is closed again?
Therefore we are a bit skeptical about MBA’s motives when they ask to sample the steel of the old bridge. We suspect they are desperately seeking any basis to again argue the old bridge is just fine and can be fixed up so that a new two lane South Avenue bridge is not needed. We also wonder about the wisdom of allowing them to independently take and test samples when they so clearly have a biased position and are seeking test results to support their position.
2.) From an engineering standpoint, we wonder, given the age, rusting and corrosion of the steel to varying degrees along the lengths of the different beams, how a sample taken from one spot on one or two stringers could be considered representative of the strength of the entire beam, let alone all of the beams? We know from past inspection reports that there have been several episodes of beam replacement over the years, so there are likely several generations of different types of steel beams (in fact, HDR’s repair memo refers to “a mix of stringer sizes” in one of the trusses). It seems to us that to use the sample test results, you'd have to accept the dubious notion that the sampled beam is uniform in condition and strength down its entire length and in addition is exactly the same as the other remaining beams. We already know that’s not the case based on the 2023 inspection report and also the fact that HDR’s repair plans call for replacing different segments of some of the stringers, apparently due to parts of the stringers being weaker and more corroded than other parts along their length.
Thus, since uniformity of steel conditions is highly unlikely, the utility of testing is questionable. Tests of the steel might be interesting, but of dubious broad application given the different ages of the various bridge components and their long history of deterioration, damages, replacements and repairs.
We hope when MDT is calculating load capacity on a bridge to be used by buses carrying school children, they will continue to err on the conservative side and take any such test results with a large grain of salt. We also hope that you, FHWA and MDT will continue to press ahead quickly with the South Avenue Bridge project, the real solution for safe access across the lower Bitterroot.
Kristin Anderson Chair
Michael Burnside
Chuck Beagle
Don St. Peter
Brian Lambrecht
Board members, Bitterroot Bridges Coalition