An investigation to determine appropriate abbreviations for variable message signs

Abstract

New Jersey transportation agencies currently display messages with abbreviations because of limited line capacities on variable message signs (VMSs). Abbreviations, however, are generally less understood than words and there was a need to evaluate abbreviated words and phrases that New Jersey transportation agencies were currently using or planning to use. The primary objectives of this research were to determine local (New Jersey) and out-of-state (Texas) driver understanding of selected abbreviations that were currently used or planned for use on VMSs by New Jersey transportation agencies. Another objective of this research was to identify the abbreviation methods used by local and out-of-state drivers. A two-phase human factors study was conducted to evaluate abbreviated words and phrases that were selected from message libraries of New Jersey transportation agencies. The purpose of the first phase was to determine the abbreviations that local and out-of-state drivers would give for words used by New Jersey transportation agencies. Abbreviations were then tested in the second phase to determine the percentage of local and out-of-state drivers that understood phrases with abbreviated words. For both phases, local drivers were surveyed in northern and southern New Jersey while the out-of-state drivers were surveyed in Texas. From the results, message phrases with abbreviations were identified that were understood by greater than 85 percent of the local drivers surveyed and were recommended as appropriate abbreviations for use on New Jersey VMSS. Also, abbreviations were identified that were understood by less than 85 percent of the local drivers which were not recommended for display on VMSs without driver education or prompt words. Abbreviations were identified for which the differences between the percentage of local and out-of-state drivers understanding the abbreviation were substantial. the percentage of northern and southern New Jersey drivers understanding the abbreviation were substantial. The results indicated that for the words studied, local and out-of-state drivers used the contraction type abbreviations most often for short words (one to two syllables) and the truncation type abbreviations for long words (three to four syllables).