Researcher: Paul Carlson
The objective of this research is to develop guidelines for providing effective nighttime performance of overhead guide signs.The objective of this research is to develop guidelines for providing effective nighttime performance of overhead guide signs as a function of site specific situations. The need for this work has stemmed from a transition covering a period from a time when, by policy and need, all overhead guide signs were lighted to the current time when only certain overhead signs are lit. When overhead guide signs are constructed with the newest retroreflective sign sheeting materials and highway font, and installed in rural areas with little to no ambient background visual clutter, research has repeatedly shown that sign lighting is not needed. But there has been little research to address or identify the conditions when sign lighting is needed.
The two critical issues we plan to address are:
- Develop guidelines to determine when sign lighting is needed.
- Determine how much lighting is needed.
TTI will measure sign luminance and background complexity in the field and then run participants through a selected route asking to find certain signs and read certain sign legends. TTI will also conduct a closed course study with VTTI. The key to this research is being able to consistently measure background complexity as it relates to the need to light guide signs, and then making a simple set of guidelines that DOTs can use without needing specialized photometric measurement devices.