Following is a discussion about placement requirements of the California SR56 (PHOTO ENFORCED) sign apparently necessary for compliance with CVC 21455.5(a)(1), which reads as follows:

"(a)The limit line, the intersection, or a place designated in Section 21455, where a driver is required to stop, may be equipped with an automated enforcement system if the governmental agency utilizing the system meets all of the following requirements:

"(1) Identifies the system by signs that clearly indicate the system's presence and are visible to traffic approaching from all directions, or posts signs at all major entrances to the city, including, at a minimum, freeways, bridges, and state highway routes."

21455.5(a)(1)'s "visible to traffic approaching" language is used as a focus point for this discussion.

It's noted that use of the connective word "and," between the phrases "clearly indicate the system's presence" and the term "visible," means that said phrase and term each have the same grammatical function in regards to the verbiage "to traffic approaching from all directions." That is to say, an SR56 sign must "clearly indicate the system's presence" to traffic approaching from all directions, and must also be "visible" to traffic approaching from all directions. If an SR56 sign only fulfills one stated condition, then the intersection may not legally be considered to be an intersection "equipped with an automated enforcement system."

The term "visible" has a number of meanings. The words "clearly indicate" appear ahead of "visible." Consequently "visible," as it is used in CVC 21455.5(a)(1) has to mean more than simply perceptible or discernable, and must mean at least, obvious and conspicuous.

When considering what "clearly indicate" might mean, being as the said SR56 sign in and of itself must necessarily comply with signage rules as to construction, and even if a sign and its text are each of a proper size and color, if it is not properly placed, it will not be capable of "clearly" indicating anything. The controlling authority on sign placement is the Manual On Uniform Traffic Control Devices (MUTCD). Therefore, if the placement of a properly constructed sign complies with all requirements of the MUTCD, it can be said to "clearly indicate" its information, and if it violates any MUTCD requirement, it cannot be said to "clearly indicate."

[The following info was updated, in Sept. 2010, to provide a working link and current page numbers.]

The MUTCD is available at the CalTrans website.  The pages referenced immediately following are found in the official Signs manual, a 27.5 MB file available at http://www.dot.ca.gov/hq/traffops/signtech/mutcdsupp/pdf/camutcd/CAMUTCD-Part2.pdf .

As of Sept. 2010, the version dated Sept. 2006 was the newest Signs manual posted at the CalTrans website.

Section 2A.16 (on page 2A-8 of the manual) titled Standardization of Location, provides as follows:

"The installation of signs, including route shields, on signal standards should be avoided unless they directly affect traffic movements in the intersection."

Figure 2A-1 (on page 2A-15) titled Examples of Heights and Lateral Locations of Signs for Typical Installations, provides as follows:

"NOTES. These sign positions are typical and should be considered a standard. When physical conditions require deviation from these typicals, they should be documented."

Section 2A.16 (on page 2A-7) also says:

"Signs should be located on the right side of the roadway where they are easily recognized and understood by road users.  Signs in other locations should be considered only as supplementary to signs in the normal locations, except as otherwise indicated."

"Option:  Under some circumstances, such as on curves to the right, signs may be placed on median islands or on the left side of the road.  A supplementary sign located on the left of the roadway may be used on a multi-lane road where traffic in the right lane might obstruct the view to the right."

Section 2A.18 (on page 2A-9) titled Mounting Height, says:

"Where parking or pedestrian movements occur, the clearance to the bottom of the sign shall be at least 2.1 m (7 ft)." 

"Option:  The height to the bottom of a secondary sign mounted below any other sign may be 0.3 m (1 ft) less than the height specified above."

Section 2B.46 (on page 2B-49) titled Photo Enforced Signs, says:

"The Traffic Signal Photo Enforced (SR 56(CA)) sign (see Figure 2B-1(CA)) shall be placed at all traffic signals where an automated traffic enforcement system is being used."

"Option:  The Traffic Signal Photo Enforced (SR 56(CA)) sign may also be used at all major entrances to the city, including freeways, bridges, and State highways."