Posted: Oct 04, 2018 by

Every ten years, the United States Census Bureau fulfills its constitutional mandate to tally the population and household totals in the United States. As you can imagine, the makeup of any particular area can change substantially in under a decade, so the Census Bureau launched the American Community Survey in 2005. The ACS uses statistical sampling to capture snapshots of our communities. While the ACS’ data is not as exact as the decennial census’, it does provide insights into emerging trends relating to where and how people live.

What does this have to do with GreenTrips or our community? The American Community Survey includes questions on how respondents get to work, making it a great tool to see changes in transportation choice.

Before we take a look at the trends for our community, it is important to note some caveats around this information. First of all, GreenTrips and the Census Bureau are concerned with different geographies, with GreenTrips focusing on a smaller area. GreenTrips focuses on the Transportation Planning Organization (Hamilton and Catoosa Counties, as well as the northern portions of Walker and Dade Counties). The U.S. Census Bureau categorizes all of Hamilton, Marion, and Sequatchie Counties in Tennessee and Catoosa, Dade, and Walker Counties in Georgia as the Chattanooga, TN-GA MSA. Additionally, GreenTrips focuses on trips, and rewards any trip into, within, or out of the TPO area. The ACS looks at the households contained within the Chattanooga, TN-GA MSA.

The American Community Survey only asks about journeys to work. GreenTrips does spend a lot of time focusing on this because of the outsized effect these trips have on congestion (if you’re like most people, the worst traffic you encounter is coming from or going to work), but we reward any GreenTrip. Any trip that a member takes that could have been a drive-alone trip counts for GreenTrips, not just home-to-work commutes.

Finally, It’s important to note that the ACS doesn’t capture the frequency that members use different types of transportation. The wording of the question is  “How did this person usually get to work LAST WEEK? If this person usually used more than one method of transportation during the trip, mark the box of the one used for most of the distance.” This limits answers to what happened last week (so if a person bikes to work unless it is raining, her or his answer would depend on the previous week’s weather) and puts each commuter into a single category. If you drive alone on Monday, but take the bus on Tuesday and biked on Wednesday, GreenTrips counts all these trips but the Census Bureau puts you into a single category based on the distance you’ve covered.

In conclusion, while these two geographies overlap to a substantial degree, it is worth noting that they are not the same and that we are measuring transportation in these areas differently.

Now that we’ve gotten those caveats out of the way, let’s talk about the good news!

The Chattanooga-TN-GA MSA added approximately 10,000 new commuters last year. Our economy is growing and these new commuters are evidence of more jobs in our area. This is good news across the board for our community, but normally new jobs and new commuters lead to increased traffic. This is where we are especially excited, though, because despite adding more commuters, the portion of commuters driving alone dropped to its lowest level in three years. This not only means that the current commuting community is opting for more efficient ways to get around, but our new neighbors are too!

A closer look at the numbers reveals that the largest gains came from more people choosing to get around by bike or avoiding the commute by working from home. Our community has made investments in infrastructure supporting these modes of transportation in particular. With the fiber optic network provided by EPB closing in on 100,000 subscribers, broadband internet access is available across our city and other providers have started offering competitive products in other communities throughout the area. Similarly, bike lanes and multi-use paths like those along Martin Luther King Jr. Boulevard, Apison Pike, or the South Chickamauga Creek have made it that much easier to get around by bike. We are seeing a return on investment as an improvement in traffic congestion.

Take a look for yourself
Finally, we would encourage you to take a look at the American FactFinder for yourself. This free platform provided by the U.S. Census Bureau is an easy-to-use way to parse data across multiple themes and geographies. You might be surprised to see the gains that your city made in helping us all get around more easily!


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