ENGINEERING CONSIDERATIONS IN THE DESIGN AND PERFORMANCE OF INTERSECTION TRAFFIC SIGNING

Traffic signs are the primary interface between the roadway and the driver for communicating regulatory, warning and guidance information - day and night. To be of practical use signs must efficiently and effectively communicate their information in sufficient time to allow the driver to evaluate the relevance of the information and safely execute any required maneuver. It is the role of the Traffic Engineer to ensure that road signs will successfully communicate with the driver. The MUTCD and AASHTO "Green Book" provide information and guidance with respect to standard practices. While these documents provide an overall framework there are still engineering choices to be made for each sign installation. These choices include what signs to erect, how many to use, where to place them, and what materials to use in fabricating the sign. The objective of this paper is to outline the choices the Engineer must make and discuss the consequences associated with these choices. The choices include such things as sign size, fluorescent versus ordinary color, type of sign illumination, choice of retroreflective sheeting, use of multiple signs (i.e. redundancy), and static versus dynamic displays. The consequences of these choices are discussed in terms of cost, efficiency, and safety supported by available traffic engineering studies.