The usability of traffic signs

Guessability, learnability, experienced user performance (EUP), re-usability, and system potential are the five components that would influence the usability of a product. Usability assessments of many different types of consumer products, word processor, public library’s web site, online learning programs, and election incident reporting system have been reported. Traffic signs are probably the best known graphical symbols that we encounter along the roads and highways everyday. However, studies on the usability of traffic signs had never been seen. Three experiments were conducted in this research on investigating the sign usability in a comprehension task. Sign design features (i.e. familiarity, concreteness, simplicity, meaningfulness, and semantic closeness) and some probable user factors were also selected for detailed investigation of their effects on the five components of usability. The first two experiments used Mainland China traffic signs, while the third experiment employed Hong Kong traffic signs. No subjects participated in more than one of the three experiments. Experiment 1 was done for examining the guessability of traffic signs with prospective-users…


1 Introduction
1.1 Background
1.2 Aim
1.3 Objectives
1.4 Thesis Organization
2 Literature Review
2.1 Usability
2.1.1 The Components of Usability
2.1.2 Recent Studies on Consumer Product Usability
2.1.3 The Influence of User Factors on Usability
2.2 Graphical Symbols
2.2.1 Design Features
2.2.2 Ways to Quantify Design Features
2.2.3 Effects of Design Features on User Performance
2.3 Traffic Signs
2.3.1 Comparison of Verbal and Symbolic Traffic Signs
2.3.2 Standardization of Traffic Signs
2.4 The Comprehensibility of Traffic Signs
2.4.1 Driver Factors
2.4.2 Sign Type
2.4.3 Sign Familiarity and Sign-content Compatibility
2.4.4 Cross-Cultural Studies
2.4.5 Summary
2.5 Training
2.5.1 Symbol-Training Methods
2.5.2 Effects of Training Methods on Symbol Comprehension
2.6 Data Analysis Methods
2.6.1 Describing Data
2.6.2 Examining Relationships
2.6.3 Analysis of Pretest-Posttest Design
2.6.4 Interrater Reliability
2.6.5 Sample Size Determination
3 Experiment 1 – The Guessability of Traffic Signs: Effects of Prospective-user Factors and Sign Design Features
3.1 Introduction
3.2 Aim
3.3 Objectives
3.4 Method
3.4.1 Subjects
3.4.2 Apparatus
3.4.3 Questionnaire and Sign Features Evaluation Sheet
3.4.4 Stimuli
3.4.5 Procedure
3.5 Results
3.5.1 Guessability Score
3.5.2 Prospective-user Factors
3.5.3 Relationships between Prospective-user Factors and Guessing Performance
3.5.4 Traffic Sign Features
3.5.5 Relationships amongst Traffic Sign Features and Guessability Score
3.6 Discussion
3.6.1 Prospective-user Factors
3.6.2 Traffic Sign Features
3.6.3 Limitation
3.7 Conclusion
4 Experiment 2 – The Effectiveness of Traffic Sign Training: Effects of Training Methods and Sign Design Features
4.1 Introduction
4.2 Aim
4.3 Objectives
4.4 Method
4.4.1 Subjects
4.4.2 Apparatus
4.4.3 Questionnaire and Sign Features Evaluation Sheet
4.4.4 Stimuli
4.4.5 Procedure
4.5 Results
4.5.1 Pretest and Posttest Scores
4.5.2 Effects of Training Methods on Training Effectiveness
4.5.3 Attributes on Training Methods
4.5.4 Effects of Traffic Sign Features on Training Effectiveness
4.5.5 Signs with Least and Greatest Improvement
4.6 Discussion
4.6.1 Pretest and Posttest Scores
4.6.2 Effects of Training Methods on Training Effectiveness
4.6.3 Attributes on Training Methods
4.6.4 Effects of Traffic Sign Features on Training Effectiveness
4.6.5 Limitations
4.7 Conclusion
5 Experiment 3 – The Comprehensibility of Traffic Signs: Effects of Driver Factors and Sign Design Features
5.1 Introduction
5.2 Aim
5.3 Objectives
5.4 Method
5.4.1 Sample
5.4.2 Survey Instrument
5.4.3 Survey Administration
5.5 Results
5.5.1 Comprehension Score
5.5.2 Driver Factors
5.5.3 Relationships between Driver Factors and Comprehension Performance
5.5.4 Traffic Sign Features
5.5.5 Relationships amongst Traffic Sign Features and Comprehension Score
5.5.6 Results with the Exclusion of Drivers without Local Driving Test Experience
5.6 Discussion
5.6.1 Driver Factors
5.6.2 Traffic Sign Features
5.6.3 Limitations
5.7 Conclusion
6 Conclusion
6.1 Overall Discussion
6.2 Limitations of the Study
6.3 Contributions of the Study
6.4 Recommendations on Future Work

Author: Ng, Wai Yi

Source: City University of Hong Kong

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