Fla. Admin. Code Ann. R. 62-18.070 - Highway Measurement Sites

Sites for measuring sound from vehicles operated on highways shall meet the following requirements:

(1) Standard Sites. Standard measuring sites shall be open and free of sound-reflecting surfaces within a 100' foot radius of the microphone and a 100' foot radius of the microphone point as shown in Figure 1.

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(2) Restricted Sites. Restricted measuring sites which do not meet standard site requirements because of large sound-reflecting surfaces within the clear area (see Figure 2) may be used by applying correction factors determined from the following procedure.

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Figure 2

(a) Distance from sound-reflecting surfaces. The distances between the microphone line and its nearest sound-reflecting surface and between the centerline of the lane of travel and its nearest sound-reflecting surface shall be measured. These distances shall be located on the nomogram in Figure 3 on their respective axes, and the two marks shall be connected by a straight line. The point on the central axis that is intersected by the straight line indicates the dB correction factor that shall be applied to the sound level reading obtained from each vehicle passing through the site. (The dotted line in Figure 3 illustrates a - 2dB correction for sound-reflecting surfaces at 52' feet from the center of the lane of travel and 25' feet from the microphone line.)

1. The correction factors determined by the nomogram in Figure 3 shall be used only for sound-reflecting surfaces that are parallel to the lane of travel.

2. Basically parallel surfaces may have irregularities or projections of not more than 2 feet, measured perpendicular to the lane of travel, with the distance shown in Figures 2 and 3 measured from the nearest projecting surfaces.

3. Sound-reflecting surfaces not basically parallel to the lane of travel shall be 100 feet or more from the microphone and microphone point. This restriction does not apply to surfaces that are perpendicular to the lane of travel and behind the parallel surface for which corrections are made, such as a fence, or the side walls of a building.

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(b) Distance from Embankments. Distance measurements from smooth embankments covered with vegetation, concrete, asphalt, dirt, or other relatively smooth cover shall be made from the point where the slope begins to exceed 45 degrees above horizontal. Measurements from non-smooth embankments shall be made from the point where the irregularity begins.

(c) Restrictions. Selection of sites shall be subject to the following restrictions:

1. Sound measurements shall not be made within 100' feet of a tunnel or overpass through which the roadway passes.

2. The microphone line and the center of the lane of travel shall not be within 50 feet of any overhang exceeding 2' feet, measured perpendicular to the lane of travel.

3. Sound measurements shall not be made when either the microphone line or the center of the lane of travel is within 10 feet of any sound-reflecting surface.

(d) Change in Sound Measuring Distance. When the distance from the microphone to the center of the lane of travel differs from the 50' foot standard at a restricted measuring site (see Figure 1), the dB correction for distance shall be algebraically added to the correction for reflections to obtain the total correction.

(3) Non-reflecting Surfaces. The following objects shall not be considered sound-reflecting surfaces:

(a) Any object such as a telephone booth or tree trunk less than 8 feet wide (measured in a direction parallel to the vehicle path, regardless of height). Such objects shall be either on the opposite side of the vehicle path from the microphone or more than 10' feet from a line passing through the microphone and microphone point.

(b) Any surface less than 1' foot in height, regardless of length, such as a curb or guard rail.

(c) Any vertical surface, such as a billboard, with the lower edge more than 15' feet above the roadway.

(d) Any uniformly smooth slanting surface with less than a 45 degree slope above horizontal.

(e) Any slanting surface with a 45 to 90 degree slope above horizontal where the point at which the slope begins to exceed 45 degrees is more than 15' feet above the roadway.

(f) Chain link fences or any vegetation such as trees, bushes, shrubs, hedges, and grass.

(4) Roadway Surface. The surface over which the vehicle travels shall be dry and relatively smooth concrete or asphalt pavement.

Notes

Fla. Admin. Code Ann. R. 62-18.070

Rulemaking Authority 403.061 FS. Law Implemented 403.061, 403.415(9), 316.293(3) FS.

New 11-27-74, Formerly 17-18.07, 17-18.070.

New 11-27-74, Formerly 17-18.07, 17-18.070.