“…Lai [9] exams several GRIP message formats (‘road colour + traffic speed’, ‘road colour only’ and ‘road colour + travel time’, respectively) by using laboratory experiments and found that ‘road colour only’ was the best. Aitken et al [10–12] conducted a web survey to evaluate several prototype GRIP designs and examine the initial reception of the GRIPs and their potential usefulness to American drivers. The method of generating the colour‐coded level of a service map and predicting the travel time for the expressway GRIPs are given by Gan et al [13, 14].…”