For North Carolina, Implementation of Superstreets Means Travel Time Improvement, 

Reduction in Collisions, and Fewer Injuries and Fatalities

Increasing traffic delays at intersections are a 

common problem faced by Departments of 

Transportation (DOTs) across the nation. North 

Carolina is making strides in tackling delays in 

suburban, high-volume arterial areas through the 

implementation of “superstreets,” also known as 

restricted crossing U-turns (RCUTs). These arterial 

surface roads can move high-traffic volumes 

with less delay by re-routing left-hand turns and 

crossing maneuvers coming from the side streets. 

Instead, at an RCUT, drivers make a right turn 

onto the major highway and then make a U-turn 

through a median. 

While this may seem time-consuming, studies 

show it can result in significant time savings. At 

signalized intersections, the overall time savings 

efficiencies are due to the ability of the major 

highway to have a greater percentage of green 

time to allow the heavy through volumes of 

traffic to proceed. At unsignalized intersections, 

traffic from the minor street may actually save 

time since drivers are not stuck waiting for the 

long traffic gaps needed to go across the bust 

thoroughfare or make the left-hand turn. North 

Carolina has deployed the superstreet concept 

at intersections across the state, including a 

corridor of signalized intersections along U.S. 

Route 17 near Wilmington.

🞂 Fewer conflict points: 14 compared to 32 conflict points for conventional intersections

🞂 Reduced likelihood of crashes: 46 percent 

fewer crashes and 63 percent fewer resulting 

injuries and fatalities 

🞂 Fewer threats to crossing pedestrians

🞂 Reduction in travel time by 20 percent

🞂 Increased roadway capacity: Superstreets 

buy more years after the conventional intersection hits capacity before a major upgrade 

is needed 

🞂 Preserves the existing facility

🞂 Provides good access to both sides of the 

main road for development

🞂 Accommodates semi-trailer combinations

PROJECT CASE STUDY

Intersection and

Interchange Geometrics

BENEFITS OF SUPERSTREETS

Safety Travel Time Economic Development
Every Day Counts (EDC), a State-based initiative of FHWA’s Center for Accelerating 

Innovation, works with State, local and private sector partners to encourage the adoption of 

proven technologies and innovations aimed at shortening and enhancing project delivery

www.fhwa.dot.gov/everydaycounts

For additional 

information, 

please contact:

Mark A. Doctor, P.E. 

Intersection and Interchange Geometrics Lead 

Safety & Design Engineer 

FHWA Office of Technical Services 

mark.doctor@dot.gov

404.895.6210

Researchers at North Carolina State University 

conducted the largest-ever study of superstreets and 

their impacts, and found that the superstreet traffic 

design “results in significantly faster travel times, and 

leads to a drastic reduction in automobile collisions and 

injuries.” Although the superstreet concept has been 

around for more than 20 years, the NC State study is 

the largest analysis ever performed of the impact of 

superstreets in real traffic conditions. 

The operational analysis involved calibrating and 

validating VISSIM models of three existing superstreets 

in the State, and comparing that with results from 

models of equivalent conventional sites. The superstreet 

outperformed the conventional design at each 

location studied, reducing the overall travel time per 

vehicle traveling through the intersection. The study 

also found an average of 46 percent fewer reported 

automobile collisions and 63 percent fewer collisions 

that resulted in injury or fatality, when compared to 

similar intersections that use conventional traffic designs. 

The US-23/74 superstreet in Haywood County was studied for 12 years: 6 years before the superstreet installation 

and 6 years after. There was a 16.8 percent reduction in total collisions, including a 41.1 percent reduction in 

fatal injury collisions, when comparing the second six-year period to the first. Additionally, the NC State study 

presented significant performance and operational results, and showed a 20 percent overall reduction in travel 

times. Because of this direct positive impact on travel, DOTs are able to wait longer to make more significant 

changes to the intersections, resulting in cost savings. The travel time savings and extra capacity at higher 

volumes can buy an agency more years of acceptable operation. The study also showed that superstreets 

result in lower vehicle emissions due to the reduction in congestion and prolonged vehicle idling.

ADDITIONAL RESOURCES

🞂 Hummer, Joseph, Rebecca Haley, Sarah Ott, “Superstreet Benefits and Capacities,” North Carolina State

University, December 2010: https://trid.trb.org/view/1102462

🞂 Hummer, Joe and Matt Shipman, “No Left Turn: ‘Superstreet’ Traffic Design Improves Travel Time, Safety’,

NC State University Newsroom, Jan 10, 2011: http://news.ncsu.edu/releases/wmshummersuperstreets

🞂 Haley, Rebecca, Sarah Ott, Joseph Hummer, Robert Foyle, Christopher Cunningham, Bastian Schroeder,

“Operational Effects of Signalized Superstreets in North Carolina,” North Carolina State University,

Jan 24, 2011: https://trid.trb.org/view.aspx?id=1092928

🞂 North Carolina Department of Transportation: https://www.ncdot.gov/projects/us-1-15-501-moore/Pages/

default.aspx

🞂 “An Update on Superstreet Implementation and Research,” NC State University: http://citeseerx.ist.psu.edu/

viewdoc/download?doi=10.1.1.518.9610&rep=rep1&type=pdf

Keys to Success

🞂 Active and ongoing stakeholder

engagement and buy-in.

🞂 Decisions supported by credible and reliable

models and data.

🞂 Coordination among planning, design, safety,

and operations.

🞂 Supporting Policies: Capability to fund

improvements, multi-agency

agreements, and policies where

roadways cross jurisdictional boundaries;

driver education campaign.

🞂 Complementary Strategies: Intersection

pedestrian treatments, access management.

Updated 07/20