Driver-related factors are one of many aspects to consider when determining the appropriate sign placement and letter height requirements of road signages. To do so, here are six steps on how to determine well-placed and easily deciphered road signs.
Step 1. Determine Reading Distance
Reading distance refers to the portion of the traveling distance allotted for the driver to scan the message of a sign following the time needed to understand it, which is referred to as the reading time.
Provide a 0.5 second for each word or a number and one second for each symbol, with a total of one second reading time at least —only essential keywords for this time. Usually, people do not read every word on a sign to find the information that they are looking for.
Four words are the best word count on a sign. Having more than four words on a sign makes drivers glance it more than once, which may cause possible accidents. Add 0.75 seconds on the reading time if there are more than four words and numbers, or more than two symbols.
Another, add a 0.5 second to the reading time if the maneuver does not start upon the driver will reach signage. This extra time provides a viewing angle instantly before the driver could pass by the sign, prohibiting reading. Calculating reading distance is very technical; it is best to ask for professionals. For business signs, contact Shieldco business signage for help.
Step 2. Determine Decision Distance
Decision distance refers to the distance required to decide and initiate any maneuver, only if necessary. Drivers need to determine his or her course of action based on a sign’s message after reading it.
There are two decision time ranges. First is apply one second for simple maneuvers, such as stop, reject or choose a destination with D1-1 signage also called Destination (single), or slow down the speed.
Second is do 2.5 seconds or more for complex maneuvers like two choice points at a complicated intersection. After which, convert decision time through multiplying it by the travel speed.
Step 3. Determine Maneuver Distance
Maneuver distance refers to the distance required to finish a chosen maneuver. It relies on the course of action resolved in advance by the driver and the travel speed. Sign designers should account all the maneuvers that might be opted basing upon the signage message.
For instance, for ways with low-volume traffic, there are a few of the deceleration distance that may overlap with the lane change distance. On the other hand, for roads with high-volume traffic, there must be more time needed to find a gap.
Step 4. Determine Information Presentation Distance
Information Presentation distance refers to the total distance from the point of choice or choice point like intersection, in which a driver is looking for information. You need to add Reading Distance, Decision Distance, and Maneuver Distance to get the Information Presentation Distance.
Step 5. Determine Legibility Distance
Legibility distance refers to the distance where the sign must be legible or readable. It is based on the advance placement of the signage from the choice point and the operating speed. You need to subtract Advance Placement from Information Presentation Distance to get the Legibility Distance.
Step 6. Determine the Minimum Letter Height
Minimum Letter Height refers to the height required for any characters on a sign based on the calculated legibility distance. It should be based on the legibility index given in the Manual on Uniform Traffic Control Devices (MUTCD), which is typically 30 feet or inches.
MUTCD is an official paper published by the Federal Highway Administration (FHWA), which is under the United States Department of Transportation (USDOT). This document provides specifics of the standards used for designing, installing, and using signals, road surface markings, and traffic signs.
You need to divide legibility distance in feet by Legibility Index in feet or inch to get the Minimum Letter Height. Additionally, you should calculate the minimum symbol size based on the legibility distance of a particular utilized symbol or character. If placed before turning points requiring no maneuver before reaching the signs, letter heights are smaller.
There are two general trends on legibility distance. First, legibility distances differ by sign types. Second, legibility distances are decreased when drivers have are aged between 45-70, but not all. Hence, legibility distances for symbols are generally better than word messages.
The heights of the signs, which distance must from the ground up to the bottom of signage, vary in different areas. In rural areas, the minimum height should be at least five feet, while in urban areas is seven feet. The additional height is required to adjust from the pedestrian passage without interference.
Rebecca Nelson is a freelance creative writer. Her experience in business and digital marketing coupled with an interest in tech entrepreneurship makes her a fine contributor in the field of business and internet marketing.