Ask R. Moses: What is "future traffic?"

Today we launch a new column: Ask R. Moses. From the Strong Towns membership, we've assembled a panel of licensed engineers to answer your questions under the collective pseudonym R. Moses. In doing this, we hope to give licensed professionals a chance to speak to important issues without fear of reprisal from their peers or employers.

R. Moses is not meant to be professional engineering advice nor should be relied upon as such. Consult your own technical professional before proceeding with your own project.

The Question:

My city was going to fix a local road until the project engineer suggested they widen it because of future traffic. The area is losing population and has been for some time. What is this “future traffic” all about?

R. Moses Answers:

Photo by  Bryanwake

Photo by Bryanwake

Dear Confused,

This is a question I get a lot. Typically, future traffic means a forecasted or anticipated change in traffic demands due to development, redevelopment, changes in roadway networks, and population growth. So why is your city forecasting this growth in traffic when the data indicates otherwise?

There are a few explanations, although none of them particularly logical or satisfying, I'm sorry to say.  One reason your engineer might be suggesting a road widening is that he or she is assuming that growth will pick up at some point as it "always has." Thus, the city should be ready with a wider roadway.  

Your engineer might also justify this road widening by saying that, while your community is declining in population, the region is growing, so eventually that growth will effect you. For example, if the next county is constructing lots of new residential development, your government leaders (goaded on by local construction companies) might argue that they want those residents connected to the job centers located in your city, and that the only way to do this is by widening the road so that traffic can flow faster. We know this to be a fallacy though.

The truth is, there is absolutely NO reason to increase road capacity on a corridor serving a declining population. If the city or region is looking for transportation investments that will result in economic development to stem the tide of decline, other types of investments such as downtown streetscape or bicycle infrastructure, will be far more effective. In areas that have stable or declining population, road and street project designers should take a hard look at the best use of existing pavement, and consider changes such as narrowing travel lanes or adding bike lanes to adapt our existing infrastructure to contemporary needs.

Another important concept to think about when planning future infrastructure is “back-casting.” This means starting with your vision of the future, and then walking back to the present, thinking about what you need to do today to attain that vision. In communities where traffic is projected to grow, and there is a goal of a modal split that is more balanced between driving, walking, biking and transit than today, adding roadway capacity should be avoided. Money should be spent putting infrastructure on the ground for the other modes that need investment. We get what we design for! If you design for more cars, you will maintain or increase your auto mode share. If you make streets that are safe and pleasant for biking or walking, people will respond accordingly, even in rural and suburban areas. 

Since this question does not reveal the condition of the existing road or the context, we'll have to do a little guessing.  If it is an older narrow road with open ditches and no sidewalks, then widening to provide sidewalks, and curb and gutter drainage might be appropriate.  However, that's about a bigger goal than maximizing the number of motor vehicles lanes that could "fit" in the existing or anticipated right of way.  Mobility is the safe and efficient movement of people and goods within a transportation system; it is not simply moving cars at speed.  Unfortunately, it sounds like your engineer is just focused on imaginary car traffic.

As an engineer (and I think my fellow engineers would agree with me), I'm not against useful infrastructure. But I am against wasteful and unnecessary infrastructure. When considering an infrastructure project, even one as seemingly small as widening a road, we should always ask, Is this worth our community's money?  In the case of your local street, the answer seems clear.

Do what you can to speak out against this road widening project. Best of luck.

~ R. Moses

How would you respond to this question? Jump in with your answers in the comments!

If you have a question for R. Moses about an engineering issue or frustration in your city, we invite you to submit it here.

(Top graphic by Matthias Leyrer)

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