This is Part One of a three-part series on the Reversible Super Arterial Tollway. Part Two Part Three
Given the failure of metro Atlanta’s transportation referendum, and all the subsequent talk of a “Plan B”, I’m going to throw in some of my own suggestions on what sort of investments Atlanta can make in order to tackle its seemingly intractable traffic quagmire.
Peachtree Industrial Boulevard, north of I-285, is perhaps Atlanta’s most underrated road. According to GDOT data, the Peachtree Industrial handles over 115,000 vehicles per day. This puts it ahead of many of Atlanta’s second-tier interstates. I-985, which connects Atlanta to Gainesville, is just shy of 60,000 vehicles per day in its busiest stretch. No part of I-575 or I-675 exceeds 100,000 vehicles per day. Peachtree Industrial even edges out traffic volumes at the Georgia 400 toll plaza in Buckhead.
How does Peachtree Industrial do it?
The road is what traffic engineers call a Super Arterial. The road functions as a hybrid between an arterial roadway (meant for handling local traffic–the lanes on either side), and a limited-access roadway (such as an interstate, which can be seen in the middle).
Photo courtesy Google Earth.
If the TSPLOST had passed, Atlanta would have had a second Super Arterial, down on Clayton County’s Tara Boulevard, a densely-developed road that handles 65,000 vehicles per day–a mix of commuters and local traffic.
The Reversible Tollway Concept
Before we delve too deeply into the Super Arterial concept, let’s talk about the latest big solution for Atlanta’s traffic woes: the reversible tollway. I-75 is planned to be to be expanded with completely grade-separated, reversible toll lanes in the middle. The project, which will run from the interchange with I-285 to the 75/575 split, and a ways further up each interstate after the split, will use two main innovations:
- The variable toll. Tolls will be based on demand, with the goal of keeping traffic moving at a speed of at least 50 mph.
- The reversible lane. Additional lanes will relieve traffic flows in the peak direction (towards Atlanta during the morning, away from Atlanta during the evening)
We certainly agree this idea is better than traditional freeway expansions. Reversible lanes mean a smaller roadway footprint, and hence lower costs and environmental impacts. Tolls mean lower development costs. And variable pricing means the most time-sensitive traffic gets where it needs to go.
Limitations to the Reversible Toll Lane Concept
But does this best address Atlanta’s traffic needs? I-75 already is, by national standards, extremely wide, with up to 8-lanes on each side. Meanwhile, other cities get by with a more extensive network of more modestly-sized interstates (with, say, three to five lanes on each side). Not only do more people live closer to an interstate in these other cities (such as Nashville, Houston, and Dallas), but they also have more more options to get where they need to go.
Meanwhile, Atlantans gripe that the arterial roadways–the ones that take them from, say, the interstate to the entrance of their neighborhood–are the worst of all. These streets are jammed with commuters and local traffic, all pushing yellow lights and battling their way into double-left turn lanes.
In these sorts of situations, a Peachtree Industrial Boulevard setup would be preferable for commuters, with through traffic and local traffic separated completely.
Introducing the Reversible Super Arterial Tollway (RSAT)
How can we address all of these issues–overburdened interstates, clogged arterials, and ever-shrinking roadway budgets?
Enter the Reversible Super Arterial Tollway (RSAT). This concept takes the two innovations discussed above (reversible, barrier-separated lanes; and congestion-variable tolls), and puts them on a Peachtree Industrial Boulevard-style Super Arterial. Two or three barrier-separated lanes will run down the medians of existing arterial roadways, alleviating the peak traffic direction.
Perhaps the perfect application for this sort of roadway is SR 74, down in Fayette County. Every morning, the crush of commuters from Peachtree City and Tyrone pushes the four-lane, median-separated highway far beyond capacity–in the Atlanta-bound lanes, at least. In the afternoon, as the commuters rush home, insufficient southbound capacity on SR 74 backs up traffic onto I-85. Even during off-peak times, the growing number of stoplights along the road makes the drive cumbersome. Simply put, this roadway isn’t equipped to handle the traffic flows of about 35,000 vehicles per day.
In order to improve the situation, two barrier-separated toll lanes running down the median of the road could be built. In the morning, the toll lanes would run northbound, towards Atlanta; in the afternoon, they would be reversed. The original two lanes on either side of the roadway would remain in place, giving drivers the option of not paying the toll.
Advantages of the RSAT Concept
The RSAT concept offers several advantages over the Reversible Toll Lane concept proposed on I-75.
- Drivers have an incentive to pay the toll–even during off-peak hours. As GDOT quickly learned after implementing HOT (High-Occupancy Toll) lanes on I-85 in Gwinnett County, if there isn’t congestion, drivers aren’t willing to pay much of anything for the privilege of riding in the toll lanes. After all, the normal lanes are flowing freely, so the toll lane offers no obvious benefits. Tolls eventually fell to rock bottom levels during congestion-free periods (a penny per mile); the same outcome is likely on the I-75 project. In the RSAT concept, this isn’t the case: drivers who pay the toll have the added benefit of bypassing all the slower-moving local traffic, not to mention all the stoplights along the road. Drivers get a guaranteed speed-limit drive, and they’ll pay more for that. In some cases, a higher speed limit could be allowed for the RSAT lanes than the general lanes.
- RSATs spread capacity around, rather than concentrating it on existing corridors. As I-75′s capacity increases as a result of the toll lane project, the arterial roads that feed into it will be burdened with ever-increasing traffic volumes. By developing RSATs to relieve existing interstate corridors, we won’t place further burdens on our already-strained network of feeder roadways and interchanges.
- RSATs give commuters options. The I-75 toll lane project delivers capacity, but it doesn’t deliver options. Indeed, commuters will depend just as much on I-75 as they ever did in the past. Developing RSATs to relieve interstates will give some commuters a choice of which route to take home, and potentially dodge traffic jams in the process. Ideally, the addition of several RSATs would reduce volumes on major interstate highways.
- RSATs are built within–and primarily benefit–the existing developed footprint of metro Atlanta. RSATs primarily serve commuters within existing developed areas; putting one on SR 74 or Tara Boulevard wouldn’t be of much use to an 80-mile round trip commuter from the distant exurbs. Meanwhile, interstate widening projects, such as the 2008 widening I-85 in Coweta and Meriwether Counties, mainly help people who commute long distances into metro Atlanta. In other words, the RSAT concept would probably induce less suburban sprawl than expansions of long-distance interstates.
- Arterials tend to be a lot easier to build on than interstates. Interstate highways tend to be the most expensive roadways to alter. First, a corridor like I-75 is almost completely built-out–there’s no extra width for capacity in most places. Any additional capacity must be built entirely on structures or require realigning the entire interstate: both ruinously expensive options. Second, each time an interstate meets a surface street, it runs into a bridge, a tunnel, or an interchange. Adding new toll lanes nearly always requires the interchange or bridge to be rebuilt, costing tens of millions of dollars for each and every one you encounter. RSATs, instead, could be much simpler to implement.
- Like the I-75 HOT lane proposal, RSATs don’t cannibalize existing capacity. This proposal avoids the politically-toxic idea of tolling existing capacity.
Are There Any Similar Models?
You might be wondering if I’m completely going out on a limb with this idea. The answer is, perhaps. I know of no project in the United States that’s exactly what I’m describing (feel free to chime in if I’m wrong).
But there is at least something similar: the SR 618 reversible toll lanes in Tampa, Florida. In this project, an existing toll freeway was expanded by adding three reversible, fully-elevated toll lanes in the median. The project runs all the way from downtown Tampa to the suburb of Brandon. The SR 618 project is similar in some ways to the I-75 project, mainly in that it serves an existing limited access road. But, like the RSAT concept, it adds extra capacity to a second-tier, lower-capacity corridor where there is more space for development. The SR 618 project does not feed into a long-distance interstate, either. The elevated portion is 8 miles long, and cost $420 million in the mid-2000s–or roughly $50 million/mile. It carries over 15,000 toll-paying vehicles per day. More information on the project can be found here.
The SR 618 project varies from the RSAT concept in several ways. First, the RSAT concept is strictly for the suburbs, given the hemmed-in nature of urban arterial roads. Second, the RSAT is aimed at arterial roads, rather than expressways. But the SR 618 project has several similar features to the RSAT concept being proposed here.
In the following posts, I’ll describe where I think RSATs ought to be implemented in metro Atlanta, how much we can expect to spend on the system, and the ability of toll collections to offset development costs.