UT Knoxville engineering students propose conceptual designs for suicide barrier at Natchez Trace Bridge

UT Knoxville engineering students propose conceptual designs for suicide barrier at Natchez Trace Bridge

PHOTO: The student group charged with identifying solutions to the Natchez Trace Parkway Bridge suicide problem gathers in an open area Monday, May 6 at the John D. Tickle Engineering Building at the University of Tennessee in Knoxville, Tenn.

Pictured, from left to right, BOTTOM: Joseph Allston and Team Leader Nancy Abdo. MIDDLE: Professor Jennifer Retherford, Jay Thota, Connor Campbell and Meet Patel. TOP: Natchez Trace Bridge Barrier Coalition co-founders Sarah Elmer and Trish Merelo, and Payne Susong.

By RACHAEL LONG / Photos by Rachael Long

WARNING: This article contains and discusses information about suicide. The National Suicide Prevention Lifeline is 1-800-273-8255 (TALK).

The halls of the engineering building at the University of Tennessee Knoxville roared with sound Monday as groups of students presented a semester’s worth of work. For many, the open-house style presentation was the final task standing between them and summer.

The groups each explored different engineering problems and were asked to provide conceptual solutions to those problems. One group in particular had an assignment which asked them to go beyond the bounds of engineering and look at a problem rooted in social context: the suicide problem at the Natchez Trace Parkway Bridge.

The ‘suicide bridge’

The bridge — which as been the site of more than 32 reported suicides and is often referred to as the “suicide bridge” — is located in northern Williamson County, more than 200 miles away from the university’s campus. The project idea came to Engineering Professor Jennifer Retherford by way of Trish Merelo, co-founder of the Natchez Trace Bridge Barrier Coalition.

The coalition seeks to raise the “precariously low” 32-inch guardrails and install suicide barriers on the bridge. Merelo sought help from engineering programs all over the state to help design a barrier.

More: Bridge renowned for beauty in its setting and design also known for suicides

Retherford told Home Page earlier this year that her senior design course perfectly fit the course curriculum guidelines. The two-semester course she teaches asks students first to explore the problem conceptually, and in the second semester, to propose designs complete with calculations and drawings.

The six-person team, led by student Nancy Abdo, has spent the last several months talking to coalition members, the National Parks Service, a mentor with the Tennessee Department of Transportation (TDOT) and others to get a sense of the scope of the problem.

The Natchez Trace Parkway Bridge stands over Highway 96 on Jan. 9, 2019, in Franklin, Tennessee.

Part of what makes the project a challenge is that not only is the bridge is of historical and engineering significance, but it also sits on federal land.

Another issue is that the bridge, which turned 25 years old in March, may become eligible for placement on the National Register of Historic Places. Any superficial changes could affect its eligibility for the Register, and any engineering work would ultimately require approval from as far up as the Department of the Interior, which oversees the National Park Service.

So when the students set out in January, they had their work cut out for them and an uphill battle ahead.

Conceptual designs

The students looked primarily at top-mounted systems, and what they found is that a fence of some kind may be the most cost-effective solution. Student Joseph Allston said they may also look into side-mounted and under-mounted systems next semester, as the team found that modifying the existing guardrails would actually be much more intensive than they originally believed.

Current designs by students suggest a 7-foot fence constructed using pre-manufactured fence panels which students say would be simple to replace, as needed.

A lot of their general feedback, Abdo said, has come from their technical mentor, Houston Walker, a professional engineer and structural design supervisor for TDOT.

Team leader Nancy Abdo rearranges the group’s conceptual drawings as Trish Merelo takes a picture Monday, May 6, 2019 at the John D. Tickle Engineering Building at the University of Tennessee in Knoxville, Tennessee.

“[He’s] kind of confirmed that a design like this one we’ve been doing would kind of be the most feasible and maybe the quickest to construct,” Abdo said.

More: Engineering students examine Natchez Trace Bridge, seeking solutions to suicide crisis

During a meeting with the students in February, coalition members questioned the placement of a parking lot which sits nearby the bridge. Park Service members said it was never designed to be a pedestrian bridge, which prompted the question, “Why is there no signage saying, ‘Do not walk on the bridge?’”

While Park Service members replied that adding such signage was feasible, the engineering students decided traffic studies to evaluate the pedestrian volume was a necessary next step for the course of their project.

“We kind of want to get our heads around how many people are actually out there and if the bridge needs to be reclassified as a pedestrian bridge,” student Payne Susong said. “That’s mainly why the railing is so low, because it’s not a pedestrian bridge.”

Abdo said such a study, in order to avoid the influence of bias, would require studying foot traffic across different variables, such as different times of the year, days of the week and times of day.

Because there are many restrictions from the Park Service in regard to a project like theirs, the students said some of the biggest roadblocks they encountered in their first semester involved design.

“Knowing how creative to be with our designs has been hard because we are kind of confined by the National Park Service’s parameters that they’ve given us,” Susong said. “But we’re slowly starting to get more and more creative…as the project starts to grab hold.”

“So far we’ve kind of remained with a pretty conservative modification idea with just putting the rail on top of the bridge,” Abdo said. “We could get really creative and make the railing kind of outside the bridge, off of the bridge, below the bridge, but it’s been hard to kind of get feedback so that we can know if that’s completely derivative of us or if we can move in that direction.”

Recently, Abdo said the students have had a couple of meetings that have encouraged them to be a little bit more creative. Susong agreed that the National Park Service had been a “huge help” in giving the students direction throughout the project.

Retherford said the students began the semester with big, creative ideas about what a barrier could look like and “went really crazy with the aesthetic design.” She reminded the students that whatever they designed had to actually be something that could be installed.

When she checked in with the group later in the semester, Retherford said they had come up with the “engineer solution.”

“I do think that when they return to the project, we’ll get to the middle there, and that’s where the right solution is,” Retherford said. “I’m glad that they have thought on both sides of that question, ‘What does this look like but how does it function?’ I’m really proud that they’ve made that attempt.”

Next semester

For course purposes, Retherford said the students must design construction-ready drawings, although they will not be stamped with approval for actual construction. She said each group should end up with two-dimensional engineering drawings.

Though it’s not required, the students have tossed around the idea of creating a 3D model of the bridge which could be used as a way to test different barrier options. Retherford said some of the students have also discussed the idea of working on the project over the summer.

Although it doesn’t usually come out of the course, Retherford said one goal is to come back in the fall with a wider variety of some of the alternatives and have a 3D printed replica of a segment of the bridge.

“They were getting excited about it, and there’s a couple of them that are like, ‘We have all summer,’ and I’m like, ‘Yeah, you say that now,’” Retherford said with a laugh. “‘The beach is calling and your internship is going to be busy.’”

A project overview hangs on the walls at the John D. Tickle Engineering Building at the University of Tennessee Monday, May 6, 2019 in Knoxville, Tennessee.

Because they will be in their final semester, Retherford said the students typically start discussing what they can feasibly accomplish in their final months as students.

When it’s all said and done, some of the projects she’s seen students do in the past really do see construction. But this one likely won’t.

“When we have really close insight on kind of low stakes engineering activities, then some of those truly get built,” Retherford said. “In this case, [the bridge is] so high profile…we won’t end up with the oversight that would allow that process to go any faster.”

“It will be valid design, but it won’t have followed all the checks and measures that really have to go through a true consulting firm.”

A relationship with the National Park Service

Retherford explained that this project in particular has been more about creating professional relationships because a large entity like the National Park Service is involved.

She explained that the responsibility of the Park Service rangers and personnel is to be good stewards of the land they maintain, not simply to block every idea for change that comes their way.

“Somebody has to be that role to protect these things,” she said. “I think they’re always trying to figure out that balance of being responsible without being restrictive.”

More: Tennessee legislator introduces resolution to add barriers, prevent suicides at Natchez Trace Parkway Bridge

Retherford said that the relationships formed between the Park Service and the students this semester has been one of the biggest areas of growth for the project.

“When we started this project, I don’t think [the National Park Service] thought a solution would be realistic,” she said. “They never said we couldn’t do it, they just were like, ‘You’ve got these crazy obstacles to overcome.’”

The student group charged with identifying solutions to the Natchez Trace Parkway Bridge suicide problem gathers in an open area Monday, May 6 at the John D. Tickle Engineering Building at the University of Tennessee in Knoxville, Tennessee.

As the students have interacted with the Parks, Retherford said they haven’t yet found the answer to this problem. But they have been able to cultivate a positive relationship with the Park Service and help them understand that their goal is not to destroy the bridge’s historical significance.

“I don’t think anyone wants to take away the historic value of that bridge,” she said. “I think that was probably the knee-jerk reaction…so, I think there’s been growth partially because this isn’t us coming down on them. It is us trying to work with them.”

Follow the Coalition on Twitter at @raisethebarntb and their Facebook page, the Natchez Trace Bridge Barrier Coalition.

Follow the links below to read our full coverage of the topic.

Introduction video: Natchez Trace Bridge is a place of beauty, tragedy

Bridge renowned for beauty in its setting and design also known for suicides

Suicides from the Natchez Trace Bridge: One woman’s story

Suicides from the Natchez Trace Bridge: Law enforcement frustrations

Suicides from the Natchez Trace Bridge: Finding solutions, making changes


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