Corridors with growing traffic volumes and high crash rates are good candidates for a reduced-conflict intersection.
A reduced conflict intersection – sometimes referred to as a superstreet, a synchronized street or a median U-turn – is a general term used to describe several types of designs that can be used to improve safety and traffic flow on a highway.
There are variations to the designs, but they all function the same by reducing by almost half the number of potential locations, or conflict points, where drivers and pedestrians can collide.
Simplifying How Traffic Moves
Examples of Reduced Conflict Intersections
The most common type of reduced conflict intersection design eliminates left turns from side roads onto busy main roads.
Raised medians direct traffic from the side road into turning right. When there is a safe opening in traffic, drivers enter the flow of traffic on the main route. To go the other direction, or cross the highway, they pull into a dedicated lane – typically less than 1,000 feet away – and make a U-turn. There might be a traffic signal at this location.
Reducing the Risk of Crashes
A traditional four-way intersection has many potential conflict points. Because drivers can go in any direction from all four approaches, the likelihood of a crash is increased.
Reports in
2010 from North Carolina State University and in
2017 from the Federal Highway Administration found that:
Reduced conflict intersections without traffic signals reduced crashes 46 percent compared to conventional intersections.
Reduced conflict intersections with traffic signals reduced crashes 15 percent compared to conventional intersections.
If an intersection has a traffic signal several phases are required to move drivers through the intersection, increasing travel time. The 2010 NC State report, however, found there was still a 20 percent time savings on a signalized reduced-conflict intersection corridor compared to conventional corridors with traffic signals.
Other Benefits of Reduced Conflict Intersections
In addition to simplifying how traffic moves and reducing the risk of collisions, reduced conflict intersections also:
- Improve safety for motorists and pedestrians
- Can accommodate more traffic without increased delays
- Allow for a city or the N.C. Department of Transportation to adjust the timing of traffic signals to control the speed at which drivers move through the corridor
- Require less right of way or property impacts than adding travel lanes or building interchanges and overpasses
Economic Impact of Reduced Conflict Intersections
Economic researchers for the University of North Carolina at Wilmington spent over two years studying more than 400 reduced conflict intersections around the state for a report sponsored by NCDOT and published in 2022.
- While some locations showed a positive and significant increase in economic activity, many others had neither a negative nor positive effect, suggesting the traffic safety benefits gained by the design do not generally harm a business.
- Businesses with a large number of customers and that are busiest later in the day are more likely to believe the design makes it easier for customers to reach them.
- Reduced conflict intersections have the potential to support home values.
Residents and homeowners tended to value the improved traffic flow and traffic safety that result from a reduced conflict intersection, even if they experienced longer wait times to enter the main corridor from a side street without a traffic signal.
Frequently Asked Questions
If you own a “destination” business, your customers already are planning to visit you, and they will expect to get in and out easily without much congestion. For convenience-oriented businesses that are more impulsive stops, many factors affect the success of a business.
The price, service and product will more likely influence a customer than direct access to your store. And you may experience more traffic going by your business after medians are built, because some drivers who are making U-turns will be going by your business when they would not otherwise do so before the median was built.
Several states have conducted “before-and-after” studies of businesses where medians and reduced conflict intersections were built. According to a 2006 Federal Highway Administration report titled “Safe Access is Good for Business,” the vast majority of businesses owners in those studies said they did as well or better after access management projects, like reduced conflict intersections, were built.
The Federal Highway Administration also has reported medians did not appear to harm property values where they were installed in Florida, Minnesota and Texas.
More recently, the Louisiana Transportation Research Center determined in a final report published in November 2019 for the Louisiana Department of Transportation and Development that customer sales overall increased at 10 locations where a design similar to a reduced conflict intersection was built. The study compared the sites two years before the highway projects and two years after their construction. The decline reported at a few locations was likely due to increased competition from new businesses in the same vicinity.
An economic impact study for NCDOT was published in August 2022 by researchers at the University of North Carolina at Wilmington. The study found the installation of reduced conflict intersections had positive economic effects on some businesses and residential areas. Their analysis involved a combination of data and surveys. The researchers also relied on a process known as "remote sensing," which uses satellites, special cameras and other equipment to detect commercial, industrial and residential activity before and after a reduced conflict intersection was constructed.
In 2010, another statewide report was conducted by researchers at N.C. State University and prepared for NCDOT. The researchers found there was no significant difference in self-reported revenues between businesses on roads with medians versus those without medians. The same survey also found that businesses had a more favorable perception of medians after they were built, and 58 percent of them said the number of their customers rose or stayed the same after the median installation.
The N.C. Department of Transportation always seeks to minimize disruptions to traffic and business activity during road construction. The department will maintain customer access and deliveries to businesses for the duration of a construction project.
Additionally, NCDOT representatives will keep businesses regularly informed of construction schedules that may affect them. Customers will understand that road
construction is temporary.
Raised medians and reduced conflict intersections better manage access to the main road by redirecting drivers from minor movements. The medians and reduced conflict intersection designs lower crash rates, boost safety and improve traffic flow—even when traffic volumes grow. There are variations of reduced conflict intersection designs.