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It will not improve due to the rehabilitation any more than construction of South Avenue Bridge will eliminate drivers under the influence. The motor vehicle accident rate at and near Maclay Bridge is high as compared to statewide rates, but cure must consider the contributing factors as well as the design aspects. County and state engineers attribute the cause to sharp curves and narrow roads. Consider that there have been no fatalities in a rural area where speeding is prevalent. That means everyone slows down for the single-lane bridge and the narrow roads to a less than lethal threshold for speed. Furthermore at least 40% of these accidents cite alcohol as a contributing factor, but cited factors have not included drugs.
The preferred solution by the county and MDT would widen the replacement bridge to two lanes, widen the approaches, and straighten the route from River Pines on to South Avenue. That means those drivers under the influence will no longer have to reduce speed as much as they travel through the area of higher residential density. Greater speed increases accident severity and the likelihood of a fatality, even if the accident rate is reduced. The answer to this dilemma is more law enforcement, not more expensive bridges and roads.
No! Missoula County and Montana Department of Transportation have pursued a Categorical Exclusion (CE) to these acts. To properly apply a CE to NEPA or MEPA requirements, there can be no significant impacts from the project that are not sufficiently mitigated.
An example of proper application of a CE would be the rehabilitation of an existing bridge that would not require new approach alignments. In our view, a CE could be properly applied to the rehabilitation of Maclay Bridge, but South Avenue Bridge requires a full Environmental Impact Statement to provide for identification and mitigation of its impacts.
The term “functionally obsolete” is a designation based on scores for elements that make up the “sufficiency rating” for the bridge. The primary element contributing to this designation for Maclay Bridge is the single-lane when considered for the Average Daily Traffic count. The ADT peaked in 2010 at roughly 2600 vehicles per day, but it has since dropped to under 2000. Nevertheless the bridge does meet the criteria for the functionally obsolete designation and no contemplated rehabilitation is likely to change that.
A more important measure of functionality however is “wait time.” The average time required to wait for opposing traffic when crossing the bridge. Wait time has typically been less than 30 seconds, even at peak usage days in 2010. Compare that to wait time at any controlled intersection on Reserve Street.
The term “fracture critical” is a term chosen by engineers to identify a bridge that lacks redundancy in its structural construction. Many new bridges constructed today are fracture critical and several of the optional plans for South Avenue bridge were fracture critical.
Our concept plan for rehabilitation of Maclay Bridge includes a strengthening arch imposed on the existing truss to add strength and redundancy to the bridge, thus eliminating the fracture critical designation.
As previously discussed, Maclay Bridge is a single-lane bridge that can only accommodate traffic in one direction. That configuration requires that approaching traffic from either side must approach with caution and be prepared to stop for opposing traffic already on the bridge. At times of high use, there may be as many as four or five vehicles opposing on the bridge or ready to follow on. Practical use allows vehicles to approach and follow leading cars that are less than halfway across. If more than halfway, and with opposing traffic waiting on the other side, courtesy requires that we stop to allow the opposing traffic to come forward. This technique works surprisingly well and only rarely do drivers abandon courtesy to jump in front of opposing traffic. Wait time is usually under 30 seconds.
The only traffic calming east of the bridge on North Avenue are stop signs at Humble and at Clements. West of the bridge, on River Pines, the road is quite narrow and lined by imposing trees and poles at the pavement’s edge. These obstructions show remarkably little scaring from vehicles and their proximity to the traveled road obviously slows traffic. Though the speed limit is 35 MPH along River Pines, most traffic seems to travel under that speed, at least till they get to the slightly wider Big Flat or Blue Mountain Roads. MDT accident maps indicate the west end of the bridge and the first few hundred feet of River Pines exhibit the most accidents. Though overhead lighting and reflective traffic arrows were installed several years ago, neither the county nor MDT have compiled a report as to the effectiveness of these simple measures.
South Avenue Bridge as planned would be a two-lane structure with straightened alignments between the intersection of River Pines, Big Flat, and Blue Mountain Roads, and South Avenue. Engineers have recognized that the wider, straighter roads will lead to increased speed and have contemplated roundabouts, lane narrowing, and various other means of slowing traffic. A person can get a sense for how well this works by looking carefully at the new roundabout at South and 35th. It appears that traffic bounces over the curbs and across the base or over lawns with considerable frequency. Whether this is done as a result of DUI, inattention to driving, or simply someone that disrespects public property, the results are a preview of what could be expected at the South Avenue Bridge.