06-27-2007 Council Agenda - Laserfiche WebLink

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PRELIMINARY DRAFT FOR REVIEW BY CITY OF MINNETONKA Further changes are anticipated following Signage Workshop **Preliminary Report is specific to City of Minnetonka issues and may not be sufficient to address concerns in other communities** Appendix C — Electronic Outdoor Advertisina Device Visual Performance Definitions Conspicuity Conspicuity is the property that related to the contrast between a sign and its background and its ability to stand out from its surroundings. This is a subjective property that depends on many factors of both the environment and the viewer. Contrast Contrast is the property that defines the relationship between the brightness of the brightest color possible to the darkest color possible on a sign. In times when ambient conditions are very bright, such as a sunny day, the darkest color may still be very bright due to the sun's reflection off the sign. In these cases, the lighter colored areas of the billboard's image must be much brighter than the contrasting dark areas. Legibility The ability of the driver to read a sign is related to its legibility. Large, legible text allows the driver to read the billboard from varying distances and focus on the driving task. Conversely, with small text the driver is more likely to focus on the sign for a longer period of time and possibly wait until the sign is very close. State departments of transportation use NEMVIA's TS -4 document for this criterion. This document specifies many characteristics related to legibility including character height, resolution and color. Glare Disability Glare The first form of glare is disability glare. This occurs when a driver is exposed to a Light source so bright that it temporarily blinds the driver, impairing their ability to perform driving tasks. This temporary blindness is brief, but can be dangerous. Discomfort Glare Discomfort glare is when a light source is bright enough to distract or encourage the driver to look away from the light, but is not blinding. Discomfort glare is of particular concern in cases where a bright sign is located in the same line of sight as a traffic sign, signal or another vehicle.