- Sign complexity is measured by counting the number of information units contained on a sign. Table 18.5 captures the effects of information complexity on motorists. An information unit can describe features such as road type, event causes and consequences, time and distances, and proposed actions. Drivers process low-complexity (3 – 5 information units) messages in < 5 seconds, while high-complexity messages (> 9 information units) take over 9 seconds.
- If a message requires a driver to take urgent action, use a single word or short sentence with as few syllables as possible.
- For non-urgent messages, use up to 7 units of information in the fewest words possible. Place the most critical information at the beginning of the message.
- Do not use more than 3 – 4 information units for navigation instructions.
| Table 18.5 Relationship Between Sign Complexity and Motorist Behavior | ||||
|---|---|---|---|---|
| Length of Message | ||||
| 3 – 4 Units | 6 – 8 Units | 10 – 12 Units | 14 – 18 Units | |
| Duration of Each Glance | 1.08 seconds | 1.18 seconds | 1.20 seconds | 1.35 seconds |
| Number of Glances | 3.8 | 6.9 | 9.6 | 15.5 |
| Memory Recall | 100% | 97.5% | 75.4% | 52.4% |
CONTACT:
Chris VanDyke
Research Scientist | Program Manager
chrisvandyke@uky.edu
