While driving this week I encountered a poorly designed system that I often question. The flawed design that I came upon was a local street sign posted before an elementary school. The sign lists when the stated speed limit is enforceable in rather small print that makes reading the sign difficult. Also, this sign could lead to possible accidents that it is intended to prevent.
The flaws in this design are related to both the stages of evaluation, and execution. In order for drivers to properly evaluate the content of the sign, they must be able read the times listed while driving. Because drivers are expected to multitask in this situation, the process of evaluation is slower. This then has a direct impact on their ability to complete the stages of execution. In turn, drivers may not be able to adjust their speed accordingly.
Shown above is a simple solution to this design flaw. With this design, drivers only have to look at the sign and see if the lights are flashing, rather than reading all of the listed times. This greatly reduces the amount of time drivers spend on preforming the stages of evaluation and execution. Also, this is an effective incorporation of mental models because drivers tend to slow down when presented with flashing lights. Overall, even though the solution for this flaw may be more costly, it is a much better and practical solution.