TDOT is dedicated to implementing projects and programs that improve transportation and benefit the people of Tennessee. We have many stories to tell about how we keep the state transportation system safe and well-maintained as well as related programs that serve the needs of Tennesseans. Below are some story ideas for journalists. These ideas will be updated often, so be sure to check back from time to time. You can click here for whom to contact about the story. We also invite you to use the TDOT YouTube channel as a video source and the TDOT Flickr page for photos.
Safer and Quicker Surveys with LiDAR
Light Detection and Ranging or LiDAR, is used to scan an entire area and provide exact reference points in traffic safety studies giving a 3-D model of the road and its data. LiDAR will scan an entire area (including vertical and horizontal structures) and provide exact reference points. So on any given roadway, it can provide lane widths, slope of the road, shoulder widths, guardrail offsets and heights, sign placements and heights, bridge clearances, bridge lengths and widths, clear zone distances with locations of fixed objects (such as trees), and many other vital items. It gives TDOT more data, it's quicker and safer. This equipment also allows surveyors to do their work without affecting traffic. It was recently used on I-440 during a Road Safety Audit Review. Contact the CRO in your region to find out when you can see LiDAR in action.
A Road Safety Audit (RSA) enlists a team to improve the safety of roadways and intersections. RSAs are intended to eliminate or alleviate safety concerns that have been identified when studying crash data and from actual field investigations. RSAs are used primarily as "quick" improvements to correct safety issues such as lack of signing or striping or to correct minor geometric deficiencies. Typically, all improvements are completed within one (1) year of the final report. Safety improvements to SR 386/Vietnam Veterans Boulevard in Hendersonville were the result of a RSA after the 50 car pile-up in 2011. Those improvements included several new and enlarged signs, highly visible restriping, brighter reflectors in the center lane, and reflective strips on the guardrail and sign posts.
TDOT's Rock Fall Mitigation Program takes a positive, proactive approach to increase the safety of the traveling public. Given Tennessee's terrain and the unpredictability of weather, aging of infrastructure and other factors, the threat of rockslides is ever present. Several years ago, TDOT began implementing a Rock Fall Mitigation Program to address this issue. The program first identifies potential rock fall sites and then assigns a hazard rating to each location. The hazard rating is based on the potential for a rock fall event and the impacts to travelers and surrounding communities. TDOT then acts accordingly putting safeguards into place.
TDOT Maintenance crews make sure the trucks are calibrated and ready for winter weather. TDOT is using a new operating system that provides a more accurate salt application. It's a safer and easier system that in some cases saves up to 50% more salt.
A J-Turn requires side road movements to be made indirectly by making a right turn, traveling about a quarter-mile (pending speed and curves) on the divided main road, and then making a U-turn to proceed in the opposite direction on the main road toward the intended destination. Clear as mud, right? Please click on the video produced by our friends at MoDot. J-Turn improvements were made at four locations that had a number of side-swipe crashes at intersections:
TDOT recently received $1.4 million from the Federal Highway Administration's Highways for Life Program which encourages the use of innovative technologies and practices on America's roads and bridges. This money is going towards using "Intelligent Compaction" on four different projects across the state to improve overall pavement density and reduce highway repair costs.
Places where Intelligent Compact is used:
Open Grade Friction Course (OGFC) is porous asphalt that allows rainwater to drain through the top layer and out the side of the road. It helps prevent hydroplaning and spray from big trucks. In the photographs below, the left is before OGFC has been applied and on the right is after OGFC has been applied. You can clearly see the difference. Here's where you'll find OGFC
The Infrared Pavement Recycling machine heats up asphalt so it's able to be spread smoother and lasts longer. Crews spread asphalt and smooth it over without leaving jagged, round patches of asphalt that create a bumpy ride.
TDOT's bridge program is one of the best in the nation. In the last two years we've significantly reduced the number of structurally deficient bridges to 5.9 percent bringing Tennessee far below the national average of 11 percent deficient. The number is even lower, 3.3 percent, when you consider only the bridges for which the state is responsible. In the last four years, through our Better Bridges Program, TDOT has replaced, repaired or rehabilitated 193 of the 200 state-owned structurally deficient bridges. The future, however, holds a new challenge for Tennessee and all states. Congress passed legislation that changed funding for bridges in the federal transportation program, MAP-21. Now bridge repair must compete with other transportation needs.
TDOT has four tow plows. They do the job of two trucks with one driver. TDOT crews spray the brine before the rain, sleet or snow begins. Once the snow starts that's when we drop the salt. TDOT's Snowbusters fact sheet is updated/released every winter.
TDOT is creating a new long-term vision for transportation in Tennessee and public input is needed. This 25-Year Long-Range Transportation Plan provides the foundation for prioritizing transportation investments across Tennessee. The updated plan will aid in accomplishing TDOT's mission to serve the public by providing the best multimodal transportation system in the Nation.
In February 2012, TDOT and the Tennessee Department of Safety & Homeland Security signed a new agreement to ensure public safety and restore Tennessee roadways to full capacity as soon as possible following highway incidents. The agreement states the goals and objectives when a serious crash occurs, clearly defines the responsibilities of those responding to the incident and includes a number of new procedures such as classifying events and continual reassessment of the situation. One of the most important goals is clearing the roadway within 90 minutes, when possible.
When a tour bus carrying a church group blew a tire, crossed the median and crashed into oncoming traffic killing 8 people everyone wanted to know why the cable barriers didn't stop the bus. There are no guardrails approved by the federal government designed to stop a vehicle the size of a bus, and concrete barriers are not designed for depressed grass medians like in this case. TDOT uses Level 4 cable which is recommended by the National Transportation Safety Board. It can withstand a 17,600 pound truck impacting at 50 miles per hour. The bus in this case was reportedly about 40,000 pounds. Tennessee has 300 miles of median cable barriers across the state.