Cal. Code Regs. Tit. 8, div. 1, ch. 4, subch. 4, art. 10, app A
Visibility Test Procedures (Non-Mandatory)
A. General Requirements.
1. Scope and Application. These test procedures may be used to determine compliance with Section 1591(m)(5).
2. Definitions.
a) Exhaust Retrofit. An emission control device installed on a vehicle after the vehicle's manufacture, including, but not limited to, modified or added sections of exhaust pipe that connect the emission control device to the engine. For the purpose of these test procedures, an exhaust retrofit does not include an exhaust stack. A modification or addition made to a vehicle to install an exhaust retrofit, such as an expanded engine compartment hood or added heat shield, shall be considered part of an exhaust retrofit.
3. All sections of the exhaust retrofit shall be evaluated in accordance with the test procedures in Section B. A retrofit passes the visibility test if all sections of the retrofit meet the criteria for passing the visibility test in subsections B.1.b or B.2.d. It is not necessary for all sections of the exhaust retrofit to pass the same test criteria, but all sections must pass at least one of the test criteria.
B. Visibility Test Procedures and Criteria.
1. Determine which sections of an exhaust retrofit are inside the Original Equipment Manufacturer (OEM) engine compartment as follows:
a) Determine the location of the retrofit section with respect to the OEM engine compartment.
b) The retrofit section passes the visibility test if the section is located inside the boundary of the OEM engine compartment.
2. Evaluate retrofit sections outside the OEM engine compartment as follows:
a) Position the vehicle as instructed in Section D.
b) Draw a rectangular boundary line on the ground 40 inches outside of the smallest rectangle that encompasses the perimeter of the vehicle. If a bucket or blade is attached to a vehicle, it shall be placed in the traveling position and shall be considered a part of the vehicle when drawing the boundary line to the front and rear of the vehicle, but not to the sides.
c) Position a camera as instructed in Section G and photograph the exhaust retrofit from the driver's view.
d) The retrofit section passes the visibility test if photographs taken in accordance with subsection B.2.c. demonstrate that it meets one of the following test criteria:
(i) The retrofit section is below the driver's view to the edge of the vehicle (see Figure 1), or
(ii) The retrofit section does not block the driver's view of the rectangular boundary line drawn according to subsection B.2.b.
C. Test Records.
1. Create a written record for each vehicle that passes the visibility test, unless all sections of the exhaust retrofit(s) are inside the OEM engine compartment. The record shall include the following information:
a) Type of vehicle, manufacturer, and model number;
b) Vehicle identification number;
c) Manufacturer and model of the exhaust retrofit;
d) The picture(s) demonstrating that the exhaust retrofit passes the visibility test criteria;
e) A statement to the effect that the vehicle was evaluated in accordance with the visibility test procedures and met the requirements for passing the test;
f) The printed name and signature of the person conducting the visibility test along with that person's contact information; and
g) The test date.
D. Vehicle Position.
1. Park the vehicle on an area of compacted earth or paved surface with a gradient of no more than 3% in any direction.
2. Turn off the vehicle engine, set the parking brake, and block the tires. Position attachments, such as buckets and blades, in the traveling position and block them in place. The bucket or blade may be lowered to the ground instead of being blocked in the traveling position, provided that this lowered position does not affect the visibility test results.
E. Seat Reference Point.
1. Locate and mark the seat reference point, as follows:
a) If the seat pan has a tilt feature, adjust the seat pan so that it is as level as possible.
b) If the seat can be adjusted forward and backward, adjust the seat so that it is midway between the maximum forward and maximum rearward position.
c) If the seat height can be adjusted, adjust the seat height so that it is midway between the minimum and maximum height.
d) If the compression of the seat cushion is adjustable (air suspension seats), adjust the seat compression so that it is midway between its maximum and minimum range.
e) Use a carpenter's square to locate the seat reference point, as follows (see Figure 2):
(i) Rest the edge of one arm of the carpenter's square on the seat cushion such that it is level and bisects the seat from left to right.
(ii) Position the other arm of the carpenter's square such that it is vertical and its edge touches the most forward part of the seat backrest.
f) Mark a point on the center line of the seat 4 inches in front of the most forward part of the backrest. This point is the seat reference point.
F. Camera Lens Height.
1. The camera lens height represents the eye level of the average height and weight driver when sitting in the driver's seat. For seats that do not sink or compress when occupied, the camera lens height is 30 inches above the seat reference point on the unoccupied seat. If a seat sinks or compresses when occupied, such as an air suspension seat or a seat with a cushion, the average driver's eye level, when sitting in the seat, will be lower than 30 inches above the seat reference point on the unoccupied seat, in which case seat compression is to be determined by following these steps:
a) Select a person weighing at least 195 pounds to represent the driver. The driver shall sit on a hard bench or similar surface that does not compress when sat on. Measure and record the distance from the seat surface to the top of the driver's head. This distance is represented by distance D1 in Figure 3.
b) With the driver seated upright in the driver's seat (with the seat adjusted as described in Section E.) measure and record the distance from the top of the driver's head to an overhead reference point directly above. This distance is represented by distance D2 in Figure 3. If an overhead reference point, such as a cab ceiling or a roll bar, is not available, construct an overhead reference point out of plastic pipe or other material.
c) With the seat unoccupied and adjusted as provided in Section E, measure the distance from the overhead reference point to the seat reference point. This distance is represented by distance D3 in Figure 3.
d) Calculate seat compression as follows:
Seat compression = D1 + D2 - D3, as illustrated in Figure 3.
2. Calculate the camera lens height as follows:
Camera lens height = 30 inches minus the seat compression.
G. Camera Lens Position.
1. The camera lens position represents the eye position of an average height and weight driver. Position the camera lens such that:
a) It is directly above the seat reference point,
b) The distance between the center of the lens and the seat reference point is equal to the camera lens height calculated in subsection F.2, and
c) It points directly towards the retrofit.
Cal. Code Regs. Tit. 8, div. 1, ch. 4, subch. 4, art. 10, app A