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Center for Advancing Research in Transportation Emissions, Energy, and Health (CARTEEH)

A USDOT University Transportation Center

Improve Road Traffic Flow

Improving road traffic flow through road infrastructure remodeling efforts can significantly reduce congestion, vehicle idling, emissions, and noise levels.1,2,3,4 Traffic flow can be optimized through various road design techniques such as: 5
– Adding more vehicle lanes to congested roadways
– Converting intersections to roundabouts to help allow free traffic flow
– Interchange layouts to direct traffic to other roads
– Traffic light synchronization

Urban traffic control (UTC) is a specialized traffic management method that lessens the effect of stop times on vulnerable road users by coordinating traffic signals in a centralized area.6 The steps necessary for traffic control must be outlined in a traffic management plan.7 At its most basic level, urban traffic control is accomplished by employing a system of signs, signals, and markings. To ensure that the traffic control devices provide motorists with a clear and straightforward message, sophisticated technical requirements are applied.8 Numerous safety advantages may be obtained by safely and efficiently managing traffic, including a considerable reduction in car crashes.9

Considering this strategy will help achieve the goal of the following objectives

  • Less Contamination
  • Less Emissions
  • Less Traffic Noise
  • Connectivity and Inclusion
  • Healthy Destinations
  • Less Traffic Violence
  • Active Transportation
  • Green Space

Transportation lifecycle phases

This strategy is associated with the following transportation lifecycle phases:

  • Construction
  • End of Life
  • Maintenance
  • Material Selection
  • Operations
  • Policy and Planning
  • Project Development

Who's involved

  • MPOs
  • Transit agencies
Improving road traffic flow through road infrastructure remodeling efforts can significantly reduce congestion, vehicle idling, emissions, and noise levels.1,2,3,4 Traffic flow can be optimized through various road design techniques such as: 5
– Adding more vehicle lanes to congested roadways
– Converting intersections to roundabouts to help allow free traffic flow
– Interchange layouts to direct traffic to other roads
– Traffic light synchronization
Urban traffic control (UTC) is a specialized traffic management method that lessens the effect of stop times on vulnerable road users by coordinating traffic signals in a centralized area.6 The steps necessary for traffic control must be outlined in a traffic management plan.7 At its most basic level, urban traffic control is accomplished by employing a system of signs, signals, and markings. To ensure that the traffic control devices provide motorists with a clear and straightforward message, sophisticated technical requirements are applied.8 Numerous safety advantages may be obtained by safely and efficiently managing traffic, including a considerable reduction in car crashes.9

How it Helps

Improving the flow of traffic on roadways can reduce systemwide congestion, travel time, and emissions that contribute to greenhouse gas formation and climate change.10 This traffic management technique eliminates the need for frequent acceleration and deceleration and can, therefore, reduce overall highway traffic noise. Additionally, minimizing travel delays can have safety benefits by reducing reduce stress levels and improving mental health if drivers have an easier time reaching their destinations in a timely manner.

Implementing

Alternate Forms of Transportation:

Although prioritizing roadway design improvements can greatly enhance traffic flow, these design characteristics should be carefully implemented to ensure that they do not negatively impact users who choose alternative transportation options like biking, walking, or using public transit. For example, increasing the number of lanes on congested roadways can decrease the space available for safe sidewalks, potentially leading to fewer travelers utilizing this transportation mode. Additionally, traffic signal optimization should still include pedestrian crosswalk timing so that these road users can get to their destinations.

Use of Automatic Traffic Management Techniques:

Automated traffic techniques are more effective than manual traffic controls like traffic police officers. Traffic cameras and traffic signals should be employed to take pictures of the traffic volume on the road. IRIS (Intelligent Roadway Information System), which monitors and controls traffic on highways and interstates, is also highly recommended.11

Traffic Management Tools:

Successful urban traffic control involves traffic management plans or traffic control plans, standard operating procedures, temporary traffic management plans, and equipment such as an emergency wand, delineator, traffic cones, cable protector ramps, speed bumps, safety vest, warning signs, and an effective traffic management team.12

Potential Barriers:

In some areas, a lack of familiarity with roadway characteristics can be an impediment to implementing some designs. For example, roundabouts and certain types of interchange designs are not common in some areas of the country, so road users should be well aware of how to navigate these changes.

Examples

1) Diverging Diamond Interchange (DDI)

The diverging diamond interchange (DDI) has been gaining popularity in the United States in recent years due to its elimination of left turns and its enhancement of road traffic flow by targeting congestion. A DDI can also incorporate safe pedestrian walkways and crosswalks that involve crossing fewer lanes of traffic.

https://safety.fhwa.dot.gov/intersection/crossover/fhwasa14039.pdf

2) Carnegie Mellon University’s Scalable Urban TRAffic Control Study

Carnegie Mellon’s Scalable Urban TRAffic Control (SURTRAC) is an example of a smart traffic control system designed to optimize traffic signals and improve traffic flow. It utilizes a series of cameras to provide traffic flow information and maintain optimal flow. This technology found a 26% reduction in travel time as well as a 21% reduction in projected vehicle emissions.

https://www.cmu.edu/piper/news/archives/2012/october/smart-signals.html

3) International Traffic Safety Data and Analysis Group (IRTAD)

International Traffic Safety Data and Analysis Group (IRTAD) is an organization that seeks to promote understanding of road safety on a global scale and help lower the number of traffic fatalities. The International Road Traffic and Accident Database, which provides an empirical foundation for cross-national comparisons and more effective traffic safety regulations, serves as the foundation for its work. It gathers and combines data from around the globe on traffic accidents.

https://www.itf-oecd.org/IRTAD

1. Anderson, N. (2021). Reducing Transportation Emissions Means Focusing on More Than Just the Tailpipe. INRIX. https://inrix.com/blog/reducing-emissions/
2. Applied Information. (2019). How Smart Traffic Signals Can Help Meet Emissions Targets. https://appinfoinc.com/how-smart-traffic-signals-can-help-meet-emissions-targets/
3. Stevanovic, A., et al. (2009). Optimizing Traffic Control to Reduce Fuel Consumption and Vehicular Emissions: Integrated Approach with VISSIM, CMEM, and VISGAOST. Transportation Research Record: Journal of the Transportation Research Board, 21281. https://doi.org/10.3141/2128-11
4. AASHTO Center for Environmental Excellence. Traffic Noise & Transportation. https://environment.transportation.org/education/environmental-topics/traffic-noise/traffic-noise-overview/
5. Slowey, K. (2017). How planners are chasing better traffic flow with design. Construction Dive. https://www.constructiondive.com/news/how-planners-are-chasing-better-traffic-flow-with-design/506500/
6. TRL Software. Urban Traffic Control (UTC) Powered by SCOOT 7. https://trlsoftware.com/products/traffic-control/urban-traffic-control/
7. Canadian Centre for Occupational Health and Safety. (2016). Road Work - Traffic Control Zone. https://www.ccohs.ca/oshanswers/safety_haz/road_work/traffic_control.html
8. tbf Traffic. What is Traffic Management. https://www.tbftraffic.com/what-is-traffic-management/
9. Hobbs, F. D., et al. (2021). Traffic control. Encyclopedia Britannica. https://www.britannica.com/technology/traffic-control
10. Mansour, A. I., et al. (2022). Investigating the Effect of Traffic Flow on Pollution, Noise for Urban Road Network. IOP Conference Series. https://iopscience.iop.org/article/10.1088/1755-1315/961/1/012067/pdf
11. Pashupatimath, S. G., et al. (2018). Different Techniques Used in Traffic Control System: An Introduction. International Journal of Engineering Research & Technology, 63. https://www.ijert.org/research/different-techniques-used-in-traffic-control-systeman-introduction-IJERTCONV6IS03008.pdf
12. Hauzan. (2021). How to Improve Safety by Implementing Traffic Management. https://safels.com/traffic-management/