1. Bai, Y., Huang, Y., Schrock, S., Li, Y., 2011. Determining the Effectiveness of Graphic-aided Dynamic Message Signs in Work Zone. Final Report on Research Sponsored by the Smart Work Zone Deployment Initiative, Iowa Department of Transportation, and Federal Highway Administration, July 2011, 140 pp.
2. FHWA, 2003. Portable Changeable Message Sign Handbook. Report No. FHWA-RD-03-066, U.S. DOT, Washington, D.C.
3. FHWA, 2009. Manual on Uniform Traffic Control Devices 2009 edition. U.S. DOT, Washington, D.C.
4. FHWA, 2010. Highway Statistics 2010. U.S. DOT, Washington, D.C.
5. Knoblauch, R., Mitzburg, M., Seifert, R., McGee, H., Daily, K., 1995. Uniform Traffic Control and Warning Messages for Portable Changeable Message Signs. Report No. FHWA-RD-95-171, Washington, D.C.