NOTE: The information below was posted in 2015 as the Grove Traffic study was being conducted.
For up-to-date information about our traffic solutions, please watch the traffic presentation made at our Planning Meeting on March 30, 2016. Click here to watch the video. Complete details about our presentation are on the March 30 Master Plan page.
The 4 Most Important Facts About Traffic and The Grove
A recent article in the Rosedale neighborhood newsletter raises the specter of The Grove someday generating 24,000 new car trips daily on the area roadways. That is not the case, and misinforms about how traffic analysis works. This may be causing unnecessary concern about The Grove's traffic impact. We have gone to great lengths and expense to minimize the project’s impact on traffic congestion.
Here are the most important facts to know about traffic and The Grove.
Fact 1: The Grove will not generate additional congestion. Specifically, it won’t generate 24,000 new car trips per day on the area roadways.
Here’s why. Let’s first understand the definition of a “TRIP” as it applies to the study of traffic engineering. A "trip" is a measurement of activity. It is scored every time a person crosses the threshold of a building—both when that person enters and again when he or she exits.
In a mixed-use development, these add up super fast. Suppose you live and work in a mixed-use development, and you leave home and go to five different places within that mixed-use project:
- Home (one trip)
- Coffee shop (two trips)
- Office (two trips)
- Lunch (two trips)
- Office (two trips)
- Grocery (two trips)
- Home (one trip)
As shown, that’s 12 "trips" without leaving the project—without even getting into a car. These are called “internal capture” trips.
The City of Austin allows for adjustments to traffic generation projections for such internal capture trips, as well as adjustments for “pass-by” trips (for those drivers already on the road that stop by a particular use), and also for transit trips.
If we apply conservative adjustments, like the ones used by the City of Austin, the total daily trips projected for the Grove in its current TIA are actually closer to 17,000 daily round trips. This is far less than what was represented in the Rosedale newsletter. To be clear, these trips are spread throughout the entire day, and are round trips (both leaving and returning), so the number of new cars is actually half that number. Keep in mind, a very large portion of these trips are the result of incorporating the sort of neighborhood retail uses that make The Grove such a great mixed-use opportunity. In any case, the roadways in the area have sufficient capacity for this daily amount.
As discussed below, it is the intersections that need improvements.
In addition, recent studies suggest that the Institute of Transportation Engineers' (ITE) rates, as currently required by the City of Austin, generally overestimate the actual car trips generated by a project. And in particular, ITE rates overestimate urban in-fill projects, such as The Grove. The ITE manuals are based on traditional suburban vehicle dependent developments—not on urban infill mixed-use developments.
The reason for this overestimation is that the ITE manuals do not differentiate between urban or suburban, or infill versus green field. The ITE rates can overestimate the number of car trips for an urban infill project by as much as 90%. So those 17,000 daily round trips are very likely to be a whole lot less!
Next, let’s look at how intersections are graded. Traffic congestion is a result of DELAY at an intersection. The shorter the delay, the more traffic keeps moving and the less congestion there is, so the study of traffic focuses on the amount of DELAY at each critical intersection around a project.
Each intersection is given an operational grade or Level Of Service (LOS) measured at the highest peak hour of traffic for that given intersection.
Grades “A” through “F” are assigned based on LOS performance. Intersections operating at LOS "A" are the best, most efficient ones. LOS “F” intersections are failing, meaning they have unacceptable wait times.
Delays at intersections are the cause of CONGESTION.
We applied this methodology to the intersections the City told us to study around The Grove, and found answers to crucial questions, such as:
Question: Will the mixed-use nature of The Grove help keep traffic off the roads through ‘internal capture’ or basically by people staying at The Grove?
Answer: In the context of a fully formed mixed-use project, a significant amount of traffic is removed. Several recent studies of projects similar to The Grove suggest that ITE methodologies overestimate the number of vehicular trips mixed-use infill projects generate by an average of 80-90%. Click here to read the study, "Trip Generation for Smart Growth Projects.”
Question: Can we convert car trips into transit, pedestrian or bicycle trips coming primarily from the surrounding neighborhoods?
Answer: Yes! We are planning The Grove so surrounding residents DO NOT have to access the site by car. We are integrating this project into the existing community, and we hope to convert as many “car” trips into pedestrian and bicycle trips as possible. If we don’t open up the project to the surrounding community through connectivity, the number will be reduced.
This is why we are working hard to integrate the project into the community. We have a connection to the south neighborhoods along Shoal Creek. We even went so far as to purchase a house to the north of the project to ease traffic flow, and to promote pedestrian connectivity in the middle of 45th between Bull Creek Road and Shoal Creek.
We also are installing pedestrian crossings (click here to watch an example) on the north and west sides of the project—three such connections on the west side.
Question: What has been done to mitigate the impact of the remaining vehicle trips that will actually be added as a result of the project?
Answer: This brings us to FACT 2.
Fact 2: The changes we are recommending, together with those being implemented at MoPac, will make the intersections work equally or more efficiently than they do—and equally or more efficiently than they would in 2024 if the project was not built.
In other words, we are maintaining, or will improve, the Level of Service at the critical intersections around the project. By doing so, we keep the delays down and avoid adding to congestion.
What changes are we making? See the picture below:
We plan to completely mitigate the peak hour congestion by fully funding (well in excess of City requirements) the improvements needed to keep traffic flowing at intersections. Keeping traffic flowing is also the way to cut down on cut-through traffic. (Note: Normally the City would require us to fund 28-30% of these improvements. Instead, we are funding 100% of the improvements and we are going to build them ourselves in an effort to get them built ASAP and avoid delays.)
The improvements we recommend will make the intersections work more efficiently and safer than they do today. Changes include:
- Reconfiguring the 45th/Bull Creek Road intersection within the current right-of-way
- Adding Left Turn Lanes within Bull Creek Road
- Adding a Traffic Signal at Jackson and Bull Creek Road
- Fully funding and constructing these improvements
Fact 3: We’re working to make The Grove extremely accessible and safe for families, walkers, bikers and runners.
We’re conducting a multi-modal study to identify alternative ways to get to and from The Grove, so visitors don’t have to rely on a vehicle, and address cut-through traffic. We will provide the study as soon as it is complete.
Here is a preliminary analysis of existing conditions in the area. Let us know if you see anything that should be on there.
Fact 4: MoPac improvements are being built to help MoPac, which will also reduce cut-through traffic on Bull Creek. So the traffic that should be on MoPac now (that's causing a lot our congestion) will get back onto MoPac and stop cutting through on Bull Creek.
Also, our improvements and stoplights along Bull Creek will substantially slow the speed of cut-through traffic, which will make the area safer and further reduce cut-through cars, because they will be more inclined to stay on MoPac.
We hope that this helps dispel some of the misinformation that is circulating about traffic relating to The Grove at Shoal Creek. If you have input, we would love to hear it, drop us a note here.