Twenty older drivers, aged 63 to 81 (average 72.1), with corrected visual acuity ranging from 20/20 to 20/29 (average 20/25), evaluated six sign material and lighting combinations under night-time conditions on US Route 30 near Mansfield, Ohio. The tested material combinations, all unlighted unless noted otherwise, were (legend on background) beaded Type III on beaded Type III, lighted beaded Type III on beaded Type III, Type VIII on microprismatic Type III, Type IX on beaded Type III, Type IX on Type IX, and Type VII on beaded Type III. Evaluators sat in the passenger seat and middle centre seat of a 2002 Dodge Caravan. Headlights were kept on low beam. The evaluation loop was driven twice, once approaching signs in the left lane, and once approaching in the right lane. The evaluators completed questionnaires regarding sign visibility, legibility, and appearance after driving under each sign group and also an exit interview on the same topics at the end of the evaluation. Based on questionnaire responses, the highest rated sign groups in terms of legibility and visibility were Type IX on Type IX and Type VII on beaded Type III, which in the exit interview were deemed acceptable for night-time use by 80% and 65% of evaluators, respectively. In contrast, the lighted beaded Type III on beaded Type III sign, representing existing signing practice in Ohio, was deemed acceptable by only 40-45% of evaluators. The Type VIII on microprismatic Type III sign performed about as well as the lighted sign group, receiving higher scores on the relevant questions on the Exit Interview (60% for legibility, 55% for visibility), but performing worse on the Sign Evaluation Forms. The Type IX on beaded Type III, a favoured option in the previous study, performed noticeably still worse, and the unlighted beaded Type III on beaded Type III had the worst performance overall, as was the case in the previous study. Given that the Type IX on Type IX and Type VII on beaded Type III was clearly favoured by evaluators over the lighted sign group, it appears that switching from lighted signs to unlighted signs using Type VII on beaded Type III or Type IX on Type IX materials may represent an actual improvement for older drivers, in addition to having benefits in terms of saving on electricity, lighting maintenance costs, and worker/traffic hazards. With the greater needs of older drivers, the use at short distance of Type IX on Type IX signs instead of the previously suggested Type IX on beaded Type III is recommended. (Author/publisher)
Abstract