Scott Suchy photo illustration

 If you’re looking for one thing — just one issue — that virtually everyone can agree on, it’s this: Our roads suck.

Their plethora of potholes wreck suspensions. Some are as thrilling — and scary — as roller coasters. Nails, rocks, glass and other trash eat tires, causing Charleston drivers to spend millions of dollars more on maintenance than they should. 

“Driving on deteriorated roads costs South Carolina motorists $1.7 billion a year — $439 per driver — in the form of additional repairs, accelerated vehicle depreciation, and increased fuel consumption and tire wear,” according to a 2022 report by a national group that analyzes surface transportation. 

Hundreds of readers on social media complained when asked, “What’s the bumpiest or worst route to drive in Charleston?” Some of their answers:

“Literally all of them.”

“Every road is trashed somewhere in the area! Worst roads ever! As soon as you leave the roads in South Carolina — even as close as the North Carolina border, roads are like night and day. Clean and smooth!”

“On Calhoun, on the approach to the James Island Connector, in front of the Children’s Hospital is terrible.”

“Fishburne Street and Hagood Avenue: If you make the mistake of driving over 25 mph, your car will look and feel like it is a lowrider with hydraulics.”

“Choose any road. They all suck.”

“What’s not the bumpiest/worst route to drive in Charleston?”

Responses filled six pages. More will stream in.

Now there is data

The biggest problem to date with complaining about roads is that complaints have been anecdotal based on experiences of drivers who have bumped and bounced along their way to work or to shop. There hasn’t really been any accessible, reliable data from drivers to back up systemic complaints. 

So we went looking for a data solution. We didn’t have the budget for a $700,000 van with lasers to test road quality. At one point, we saw a $200 gadget that could be fitted onto a car, but that seemed kind of a pain if more than one person wanted to conduct tests. 

Turns out there’s a free app called Carbin. It was developed by researchers at the Massachusetts Institute of Technology (yep, the brainiacs at MIT). According to the director of the project, it’s just as accurate as those $700,000 machines and has been used by smartphone users to crowdsource the quality of 1 million miles of roads and streets around the world in the last couple of years.

“The error between Carbin and laser measurements of the roughness profile is less than 3%,” said professor Franz-Josef Ulm, faculty director of MIT’s Concrete Sustainability Hub. “From an academic perspective, the Carbin algorithm has been published in peer-reviewed journals, which is critical to ensure scientific value of the development. This gives us great confidence …

“But ultimately … the question is will we do something meaningful for our community: improving our roads for reducing fuel consumption, for improving the air quality, for providing mobility solutions for all.”

Data reveal how bad Charleston’s roads are

City Paper staffers crowdsourced Carbin on local roads and streets, as highlighted by the chart below. (To view the full chart of data collected by City Paper staffers, click here or on the image below.) According to the app’s road quality score based on the commonly-accepted International Roughness Index (IRI), well-maintained roads have an IRI rating of less than 62 inches per mile, while poor-quality roads have IRI values greater than 128 inches per mile.

For the full chart of data collected by City Paper staffers, click here or on the image above.

In the Charleston area, none of the 40+ routes measured by the City Paper scored less than 62. Read that again: None. That means Carbin ranked no roads as having a good quality. More importantly for peninsular Charleston: Every one of the 21 city streets and roads measured scored above 127, meaning that every measurement collected in downtown Charleston showed the road was bad.

Some good news? Data generally showed better road quality in other areas of the county. Most roads measured in West Ashley, James Island, North Charleston and Mount Pleasant were smoother, scoring IRI ratings between 62 and 127 inches per mile. Translation: These roads weren’t smooth, but they weren’t nearly as horrible as Charleston’s streets. 

One of the best roadways: The Arthur Ravenel Jr. Bridge over the Cooper River, a road without a roadbed. (IRI score = 74)

The worst? Chalmers Street (454), which makes sense because it’s a short, old-timey cobblestone byway. Also bad: Line Street (322), Hagood Avenue (276), Ashley Avenue (243) and Calhoun Street (218).

Note: Most of the measurements we made were for relatively short distances as streets don’t go on for miles. We noticed, however, that when Carbin collected data over several miles, scores typically dropped. Most likely that’s because longer routes have long distances of relative smoothness with intermittent choppiness. Some downtown streets, however, are continually bouncy and don’t have smoothness to round down scores.

What public officials say about roads

There are two main reasons that Charleston has sub-par roads and streets. 

First, much of the city is built upon filled-in marshland. (It is called the “Lowcountry” for a reason — it’s close to sea level, tides, flooding and shifting ground levels.) That means roadbeds often sink as roads settle, as is the case of the roads and parking lots around Brittlebank Park, the city police station and the Joseph P. Riley Jr. Stadium. They’re built on top of an old garbage dump, which constantly compacts and settles.

“Charleston’s unique topography, soils and weather and unprecedented growth all contribute to continuous wear and tear on our local roads,” said Tom O’Brien, the City of Charleston’s director of public service.

Jason Crowley, senior program director for communities and transportation at the S.C. Coastal Conservation League, added that Charleston’s potholes represented a bigger problem: “This isn’t just about deferred maintenance. It’s also about the fact that our roads are flooding more frequently from high tides and extended rainfall. Prioritizing our stormwater infrastructure projects will also help preserve the quality of our roadways.”

Second is the interconnected hydra of funding and the huge road bureaucracy that seems to allow a lot of finger-pointing between agencies. In Charleston, the city controls 53% of its streets, which are generally maintained by the county. But the state or federal government controls the rest, many of them major thoroughfares. Both pay into county coffers for repaving, refurbishing and (fancy new term) “rejuvenation” of local roads. 

According to a county pavement management website, the state pays up to $3.5 million annually for local resurfacing projects from state gas tax funds. The county used about $4 million a year from sales tax monies for resurfacing projects. More info: One-time extra funding of $10.8 million is expected in coming months.

And how much work will be done? This year, the county anticipates resurfacing and treating 25 miles of road in Ravenel/Hollywood, West Ashley, Folly Beach, James Island and Mount Pleasant, according to county officials. The number of lane miles in Charleston County? More than 4,000. 

When asked whether people in Charleston should feel good or bad about the future of Charleston’s streets, here’s what Robbie Somerville, the city’s director of traffic and transportation, had to say:

“People should feel good and look forward to improvements of the streets within the city. With the recent influx of federal money and an increase in the state’s gas tax, more funds than ever are being made available for the maintenance of the existing streets.”

Mackenzie Kelley, Charleston County’s pavement manager, added the county’s pavement management system uses several kinds of treatments that allows it to improve more miles of roads than in the past. About 20% of the local budget is spent on preservation which saves $6 to $10 for every dollar spent on preservation.

“We take a lot of pride in always looking for new ways to help extend the life of our roads with new treatment types,” Kelley said. “Charleston County is leading the way in pavement management in not only South Carolina, but also throughout the Southeast.”

It’s clear, however, that more money will fix more roads.

City Paper staffers Samantha Connors, Michael Pham, Ruta Smith, Chelsea Grinstead, Scott Suchy and Andy Brack used Carbin to collect data for this story. Have a comment? Send to:

What you can do

Help to crowdsource road data

Over the next few months, the City Paper will profile one bumpy road a week. We’ll share this data with city, county and state officials.

We can use your help. We encourage smartphone users to download the Carbin app via the Apple store for iPhone users and Google Play for Android users. Then send us screenshots of your data showing the quality of local roads. Send to: Make sure to attach the image with the data. Please include the time of the measurement, the road you measured, where you started and where you stopped measuring.

How to use the Carbin app

If you use your smartphone to measure how much you run or walk, you are taking advantage of its internal accelerometer, which can measure orientation, acceleration, distance and more. But most phones, according to MIT’s Concrete Sustainability Hub, don’t take advantage of the robust measurements from the accelerometer. The Carbin app does. It records up to 100 measurements per second. Its designers say good results generally need three minutes of data, or 18,000 data points, to develop a “heartbeat monitor for the road.”

Tips on using the Carbin app:

  • Open the app and place it in a secure location, such as a phone holder, cup holder or center console. 
  • From a stopped position, start the app when you’re ready. 
  • Drive until you reach the place you want to stop measuring. (Get out of traffic and stop your vehicle.) Stop the Carbin app. NOTE: Don’t pick up the phone to stop the app because that may influence results. It’s best to turn off the app without moving the phone from where it has been taking measurements.
  • It may take a few minutes for a result to be ready, but click the “history” button on the app to learn more about your road’s quality.

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