Missoula Arterial Street Standard

The Missoula Arterial Street Standard (MASS) is about bringing equity, safety and vibrancy to the main streets of Missoula. Arterial literally means “life blood” and “circulation”. MIST has worked diligently to improve Missoula’s arterial street system over the past 25 years, participating in hundreds of community meetings. Tangible results can be seen, with infrastructure improvements such as sidewalks, bike lanes, turn lanes, landscaping and roundabouts.

The time seems right for a new standard that can be applied to all the arterials. By adopting this new standard, the processes of change can be streamlined and our main streets can be better connected and more consistent. Our focus is a street that works for all users with attention to people that walk, bike, use transit, use wheelchairs or other mobility devices, drive a motor vehicle, or like to linger.

Too often our streets are overbuilt for motor vehicles. This can be seen in multiple wide lanes, high design speeds, and stop-and-go intersections. Missoula suffers nearly 200 injury crashes each year, with most of these injuries happening on our arterials. A community of 100,000 people should be able to coexist in the public right of way and achieve our daily needs, without such tragic disruption. We aim to reverse the trends of increasing crashes and usher in a new era of healthy mobility.

Here are the main elements of MASS: a maximum of one travel lane in each direction for motor vehicles; travel lane widths of no more that 10’6”; protected bike lanes and protected pedestrian ways; center turn lanes where needed and where space exists; public transit stops; landscaping and green space to soften all the hard infrastructure; parking for cars, parking for bicycles and parking for pedestrians (benches).

The choice for intersections is the modern, single lane roundabout. With such an impressive safety, efficiency and accessibility record, there is no need for stop lights. Current technique and best practice means roundabouts can fit into tight spaces and still operate at a high level of service. Design is critical, however, to ensure optimum safety and accessibility, especially for the most vulnerable users of the street.

Many of Missoula’s arterials have elements of this standard already. Yet many fall woefully short. In some cases, the street should undergo a ‘road diet’ while in other cases adding a center turn lane makes sense. One of the more substantial changes is the addition of protected bike lanes (also known as cycle tracks) to all Missoula arterials. Only three blocks of protected bike lanes- on N. Higgins- currently exist.

How can this new standard be accomplished? The work is ongoing. As streets come up for remodeling, whether through larger project funds or simply repaving, we work to gain support for changes that fit the MASS standard. We are always seeking out community energy to start the process for change. Ideally this new standard would be adopted by our Missoula City Council and the Department of Public Works and Mobility, with support from the Montana Department of Transportation. With the Long Range Transportation Plan update taking place in 2024, the time is ripe for change.

The usual way a street is designed is to look at 20-year projections for increasing motor vehicle traffic, with an emphasis on rush hour. Most departments of transportation (Montana included) require streets to be built big enough and with enough travel lanes that average time delay for drivers (measured with an ‘A’ through ‘F’ rating) is under a certain threshold for that peak hour 20 years into the future. Other modes of transportation are accommodated if space and funds exist-after the car and truck traffic is analyzed, projected, and designed for.

The principles of MASS adjust this previous design system to be much more equitable for street users and community. This new standard approach allocates just enough space for the different modes of travel to comfortably move and function. The standard is not set in stone, however, as many community variables come into play. Examples of these variables include: existing and potential community right of way, current land uses, role of a particular arterial in the overall community transportation system, parking demands and citizen aspirations.

This formula below can be considered a typical standard:

8’ sidewalk, 4’ furniture zone, 7’ protected bike lane, 3’ buffer, 8’ car parking, 10’ travel lane, 10’ center turn lane, 10’ travel lane, 8’ car parking, 3’ buffer, 7’ protected bike lane, 4’ furniture zone, 8’ sidewalk. This totals 90’.

We suggest that the starting point for all of Missoula’s arterials (and there are about 16) is to utilize the above design, which takes up 90’. The standard can help the community identify appropriate trade-offs when less than 90’ exists. For instance, if only 70’ exists, due to, for example, a built-up environment, then perhaps car parking is not included on one side of the street, the sidewalks are 7’ instead of 8’, and the center turn lane goes away.

Perhaps the biggest change from current engineering and design practice with MASS is the limiting of travel lanes to one lane in each direction for motor vehicles. The inclusion of dedicated safe space for people walking and people cycling is already being enshrined in many municipal codes and design manuals, and Missoula is no different. We know of no city nor community, however, that actively limits the number of travel lanes for motor vehicles. We think Missoula should break the ice and adopt this new standard. Limiting the number of travel lanes to one lane in each direction makes sense from a safety, efficiency and equity point of view:

Safety: Multiple travel lanes in one direction within an urban area too often leads to tragic crashes.. People walking across a street are at immense risk with what is called the double threat. One lane of traffic stops while the second lane (going in the same direction) does not see the person walking and a crash occurs.

Speeds and blind spots are greatly increased with multiple lanes in one direction. As speed increases, a driver’s field of vision collapses or shrinks way down and other objects or people cannot be seen. Stopping distance exponentially increases as well as the force of any impact, as speed increases. With more distractions within today’s motor vehicles, the chance of collision is simply too large, too common and too tragic with multiple lanes in each direction. One lane in each direction for motor vehicles tends to be the safest type of arterial street design.

Efficiency: One might think that a 4-lane street can carry twice the amount of cars as a 2-lane street. This is not the case. A 4-lane street typically might carry 30% more cars as a 2-lane street. Why? Turning movements is the main answer. In an urban environment, drivers are always turning to get to a myriad of destinations. A left turn from the inner lane of a 4-lane street effectively clogs that lane to through traffic. Further, when one considers the delay from more crashes and more severe crashes, the time savings of more travel lanes tends to disappear.

There is much research showing that a 2-lane street with a center turn lane actually moves more cars- or at least as much- as a 4-lane street. A 4-lane (no center turn lane) to 3-lane conversion (also known as a road diet) is one of the most common ways to reconfigure a street for greater safety, efficiency and equity.

Equity: Streets with multiple lanes in one direction for motor vehicles tend to make an area or city feel like cars are the most important and dominant feature. Crossing these streets (with the higher speeds) is difficult and dangerous for people walking, biking, getting on or off transit, or driving. Our most severe and tragic crashes in Missoula happen on our multi-lane arterials. We know this because we’ve tracked and analyzed over 40,000 crashes over the last two decades in the Missoula Valley.

When streets are 2-lane (or 3-lane if a center turn lane exists), the feel is much different. Speeds are naturally lower- no signage and little enforcement is needed. People that walk and people that cycle feel more a part of the community, rather than apart from the community.

With fewer travel lanes, more space is available for facilities for other modes. More facilities mean more people are afforded the opportunity to use these modes, releasing the latent demand within a community to utilize active transportation. In short, some of these processes at work- limiting or reducing travel lanes while adding safe and inviting walk and bike ways- can be considered the opposite and antithesis to sprawl. Missoula can be a vibrant, active and healthy place to live, work and play while meeting the needs for many forms of travel.