Project Completion
September 2012
Project Team
- MnDOT
- USDOT
- FHWA
- Meeker County, MN
- McLeod County, MN
- U of M, Center of Excellence for Rural Safety, CTS and Humphrey School of Public Affairs
- Institute for Transportation Iowa State University
Project Documents
Minnesota Horizontal Curve Safety Improvement
Project Description
One low-cost technology that may help drivers select an appropriate speed when approaching a horizontal curve is the dynamic curve warning sign. A DCWS generally consists of a warning sign combined with a speed measuring device (e.g., radar) that activates a variable message (e.g., slow down) when vehicles are traveling above a set threshold. This project evaluated the speed impacts of three DCWSs installed in two Minnesota counties. This project was proposed as a supplement and expansion of an ongoing Federal Highway Administration (FHWA) national DCWS field study.
Lessons Learned
The project has been completed. The following lessons may be learned upon its completion:
- Speed and/or safety impacts related to a relatively new DCWS in the short-term and long-term along relatively low-volume roadways.
- Potential for additional site selection and installation guidance for future sign locations.
- Possible suggestions for adjustments to federal and state Manual on Uniform Traffic Control Devices related to the sign evaluated.
Benefits
- This project improved the information, knowledge, and guidance we have related to the installation and potential speed impacts of these sign devices.
- The information provided in this project will supplement the ongoing national study with findings from lower volume local roadway sites in Minnesota.
- Overall, it was concluded that the installation of the DCWSs generally had a larger impact on vehicle speeds at horizontal curves with lower advisory speeds and on the number of higher speed vehicles. The range of impacts and small number of study sites, however, led to the conclusion that the installation of these signs be considered on a case-by-case basis.
Next Steps
Some potential next steps related to the subject of this project may include the following:
- The results of the study could be combined with those that are produced from the ongoing national study
- A project could be completed that consider the impacts of these signs at a larger number of low-volume roadway locations.
- A project that considers potential options for signs that may produce similar impacts but be lower cost and allow more widespread installation
- Additional research on the potential impact of DCWSs on various types of vehicles and/or situations not evaluated