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In the United States, roadway departures accounted for 57,475 highway deaths between 2016 and 2018. Trees were the most harmful 

event in 10,697 of these fatalities.

South Carolina Tree Removal 

Noteworthy Practices 

South Carolina Tree Removal Initiatives and Projects 

Background 

The South Carolina Department of Transportation (SCDOT) manages more than 41,000 centerline miles of interstate, primary, and 

secondary roadways. This equates to the fourth highest total in the Nation when compared to all other state agencies. Over the last 

decade, SCDOT has successfully completed a number of safety-based projects to remove trees from the median and roadside 

environment. Prior to these projects, tree removal activities had been limited to larger widening projects or maintenance activities, 

and challenges to vegetation management contributed to narrowing clear zones. A review of statewide crashes revealed that fixed 

objects (particularly those involving trees) were overrepresented in South Carolina statewide crashes and fatalities. 

In 2009, SCDOT commissioned Clemson University to develop a technical report1 that analyzed roadside collision data and assessed

existing roadside slopes and clear zones. This study found that over a three-year period from 2004 to 2006, there were more than 

60,000 crashes involving fixed objects. During this time period, the researchers determined that trees were involved in 25% of all 

fatal crashes in South Carolina. 

Similarly, trees were the primary 

contributing factor in 50% of all fatal 

fixed-object crashes in South 

Carolina.2 Based on their assessment 

of existing roadside conditions at a 

random sampling of sites, the 

researchers further determined that 

sites where the minimum clear zone 

was not met were 42 times more 

likely to have a fixed-object crash. I-26 

experienced the most tree-related 

fatalities, and I-95 was a close second. 

Figure 1 captures the site of a treerelated fatality along I-26. 

1

 Ogle, J., Sarasua, W., Dillon, J., Bendigieri, V., Anekar, S., and Alluri, P. (2009). Support for the Elimination of Roadside Hazards: 

Evaluating Roadside Collision Data and Clear Zone Requirements. Report No. FHWA-SC-09-01, Federal Highway Administration, 

Washington, DC. 

2

 Nationally from 2016 to 2018, trees were the most harmful event for 10% of all fatalities and 19% of roadway departure (RwD) 

fatalities. Similarly, approximately 53% of fixed-object fatalities involved trees as the most harmful event. The FHWA RwD Strategic 

Plan website provides additional information regarding national crash statistics. 

Figure 1: Site of a Tree-Related Fatality along I-26 Source: SCDOT
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Projects 

Responding to the growing concerns of fixed-object crashes, in 2009 SCDOT added a tree removal component to an existing 

construction project on I-385. The project consisted of reconstruction of 15 miles of interstate, and SCDOT was able to widen the 

existing clear zone to 50 feet while the interstate was closed for construction. 

SCDOT then worked to address problem areas along I-95 and I-26 that were identified in the 2009 study. As a result of the safety 

analyses, SCDOT was able to program Highway Safety Improvement Program funds to remove trees from segments of both 

interstates that experienced high numbers of tree-related fatalities. In 2012, SCDOT and the South Carolina Forestry Commission 

jointly completed a timber harvest project to remove many of the trees along a 2.5-mile section of I-95 that was targeted as a pilot 

project due to that particular county having the second-highest number of fatalities involving trees in interstate medians in the state 

(14 fatalities from 2003 to 2008). The clear zone was increased from approximately 30 feet to approximately 46 feet. 

SCDOT then undertook a safety project in 

2014 and 2015 to remove trees from the 

median of I-26 and replace them with cable 

barrier, increasing the clear zone from 

approximately 25 feet to approximately 

46 feet. The project originally targeted 

30 miles to address fixed-object crashes 

involving trees, but ultimately only 13 of the 

30 miles were approved for clear cutting by 

the local council of governments. Figure 2

provides before and after photos of the clear 

zone along a segment of I-26. 

In 2018, SCDOT cleared trees from a 33-mile 

section of I-95, which the local newspapers 

had dubbed the “Coffin Corridor.” The clear 

zone was increased from as little as 15 feet to 

55 feet for both medians and roadside. 

SCDOT also commissioned Clemson University to conduct another research project3 that identified proven successful safety 

programs used in other states and assessed their potential to address safety concerns and reduce fatalities in South Carolina. The 

study focused on programs that could address the safety emphasis areas previously identified in SCDOT’s Strategic Highway Safety 

Plan and provided crash statistics for each emphasis area from the most recent year available (2015). One of these emphasis areas 

was roadway departure crashes. Citing the 2015 crash data, the researchers found that South Carolina had the highest fatality rate 

in the Nation for crashes involving trees and that trees were involved in 25% of all fatal crashes in South Carolina. The 2014 and 2015 

crash data did not include the full impacts of the two largest tree removal projects on I-26 and I-95, which were the highest treerelated crash locations in South Carolina. The researchers estimated that the tree-related fatal crashes in 2014 alone cost 

$2.26 billion, and that estimate would likely be even higher had the I-95 timber harvest project not been completed in 2012. 

Through a return-on-investment analysis included in the Clemson University study, the researchers estimated that clear zone 

reclamation through vegetation control and clearing of regrowth could save the state approximately $484 million. This analysis was 

based on the application of a crash reduction factor of 27% as developed in a 2010 Australian study.4 This finding suggests an 

equivalent benefit-to-cost ratio ranging from 26:1 to 38:1 on South Carolina roadways. 

3 Ogle, J., Sarasua, W., Chowdhury, M., Brown, K., Huynh, N., and Davis, J. (2017). Applying Successfully Proven Measures in Roadway 

Safety to Reduce Harmful Collisions in SC. Report No. FHWA-SC-17-08, Federal Highway Administration, Washington, DC. 

4

 Jurewicz, C., and Pyta, V. (2010). Effect of Clear Zone Widths on Run-Off-Road Crash Outcomes. 2010 Australiasian Road Safety 

Research, Policing and Education Conference, Canberra, Australia. 

Figure 2: Clear Zone Reclamation along I-26
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Project Successes—Improving Safety 

Even though data were not sufficient to apply an advanced statistical assessment, SCDOT further analyzed the available crash data 

both before and after each of the three interstate projects. Table 1 summarizes the outcome of this simple before-after comparison 

for the I-26, I-385, and I-95 projects. 

Table 1: Tree Removal Projects Before and After Crash Data 

Analyzed Crash Type by Project 

Crashes 

(All Severity Levels) 

Crashes 

(Fatal and Severe Injury) 

Before After % Reduction Before After % Reduction 

I-26 Safety Improvements 

Total Median Tree/Cable Barrier Crashes 165 73 37 4 

Years of Data Analyzed 5.0 3.3 5.0 3.3 

Median Tree/Cable Barrier Crashes per Year 33.0 22.0 33% 7.4 1.2 84%

I-385 Reconstruction 

Total Crashes Involving Trees 62 25 26 10

Years of Data Analyzed 5.0 7.0 5.0 7.0 

Crashes Involving Trees per Year 12.4 3.6 71% 5.2 1.4 73%

I-95 Timber Harvest 

Total Median Tree Crashes 22 2 12 1 

Years of Data Analyzed 3.5 2.5 3.5 2.5 

Median Tree Crashes per Year 6.4 0.8 87% 3.5 0.4 89%

Each of these projects resulted in substantial reductions in the total number of crashes involving trees as well as a cumulative 

reduction of 81% in the number of fatal and severe crashes involving trees. The numbers shown for the I-26 project represent the 

13-mile portion where trees were removed. By comparison, the total number of median tree crashes has remained consistent 

(30.2 per year before versus 30.9 per year after) within the uncleared section of the interstate. 

Challenges 

SCDOT noted several challenges that it faced in the implementation of these projects. The projects have typically required public 

outreach, and the I-26 project experienced significant public opposition. Due to concerns expressed at a public hearing, the local 

council of governments (COG) placed a provision in the state budget restricting any state funds from being spent on the project until 

approval was granted by the COG. The project was originally proposed to clear 30 miles of interstate, but ultimately, the COG only 

granted approval to remove trees along 13 miles. 

Mitigating the potential disturbance of wetlands was a major obstacle for all the tree removal projects. Given their locations in the 

lower portion of South Carolina, each project required significant environmental coordination. Some areas required clearing without 

grubbing or the installation of guardrail to minimize wetland impacts. In addition, the I-95 safety project required detailed erosion 

control measures specific to each location within the 33-mile tree removal section. This additional effort resulted in delays to the 

project. 

The Clemson University researchers also found that local tree ordinances may impact SCDOT’s ability to remove trees as a means of 

improving roadway safety. Local and county tree protection ordinances limit the number and types of trees that may be removed 

and mandate replacement. In addition, many of South Carolina’s secondary roadway locations have county-based ordinances that 

only permit clearing to 10 feet. SCDOT therefore had greater success in implementing tree removal projects on interstates, which 

were not subject to local ordinances. 
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Lessons Learned 

Based on the challenges it faced with public opposition, SCDOT shared several lessons learned for successful public outreach: 

• Begin outreach to public officials early, particularly on projects that may fall within sensitive areas. Early outreach to public

officials provides an agency with the opportunity to explain the purpose and need of the project. Gaining public officials’

buy-in early is key to keeping a project moving forward. If public officials are provided with the key background information

before they begin receiving calls from the public, they are better equipped to explain the project and allay concerns.

• Typically, informal public information meetings provide greater engagement than formal public hearings. Some individuals

may be hesitant to speak in front of a large audience at a formal public hearing, limiting who provides feedback, particularly

those whose thoughts are contrary to the majority. Less formal public information meetings provide greater opportunity for

one-on-one conversations, resulting in a more comprehensive cross section of public sentiment.

• SCDOT creates project webpages that provide copies of the public meeting materials and the project manager’s contact

information. Citizens are able to submit project feedback online via the webpage, and SCDOT’s public outreach section

tracks the number of hits on each project webpage. SCDOT has found that the number of individuals providing feedback

online has typically been far greater than the number attending meetings in person.

Based on the successful safety performance of the early tree clearing efforts, SCDOT noted that the public has generally been more 

receptive to the clear zone reclamation concept and that more recent projects have faced less opposition. 

Shaping of Standards, Policies, and Practices 

Although there is no written policy requiring a 55-foot clear zone, SCDOT’s Safety Office recommends acquiring this increased width 

on interstates experiencing high crash frequencies and where the speed limit is 65 miles per hour or greater. For interstates with 

speed limits below 65 miles per hour, clear zone values from the American Association of State Highway and Transportation 

Officials’ Roadside Design Guide are considered acceptable. The recommended 55-foot clear zone is nearly double the width of the 

maximum, previously common practice of 30 feet. SCDOT works to achieve the recommended 55-foot clear zone primarily through 

safety projects, interstate rehabilitation projects, or maintenance activities. 

For Additional Information 

For additional information about the FHWA Roadway Departure Focus State Initiative, contact Joseph Cheung, FHWA Office of 

Safety, at joseph.cheung@dot.gov. 

For additional information about the South Carolina Department of Transportation, contact Joey Riddle, South Carolina Department 

of Transportation, at riddlejd@scdot.org. 

Publication Number FHWA-SA-21-081