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6H. TTC Zone Warning Signs

§6H.01 Warning Sign Function, Design, and Application

Support

01. TTC zone warning signs (see Figure 6H-1) notify road users of specific situations or conditions on or adjacent to a roadway that might not otherwise be apparent.

Standard

02. TTC warning signs shall comply with the Standards for warning signs presented in Part 2 and in the FHWA’s “Standard Highway Signs” publication (see Section 1A.05).

03. The sizes for TTC warning signs shall be as shown in Table 6H-1.

04. Except as provided in Paragraph 5 of this Section, TTC warning signs shall be diamond-shaped with a black legend and border on an orange (or fluorescent orange) background, except for the Grade Crossing Advance Warning (W10-1) sign, which shall have a black legend and border on a yellow (or fluorescent yellow) background.

Option

05. Warning signs that are required or recommended in Parts 2 or 7 to have a fluorescent yellow-green background may have that color background in TTC zones.

06. Existing warning signs with a yellow background that are still applicable may remain in place.

07. Warning signs used for TTC incident management situations may have a black legend and border on a fluorescent pink background.

08. Mounting or space considerations may justify a change from the standard diamond shape to a rectangular shape.

09. In emergencies, available warning signs having yellow backgrounds may be used if signs with orange or fluorescent pink backgrounds are not at hand.

Guidance

10. Where roadway or road user conditions require greater emphasis, larger than standard size warning signs should be used, with the symbol or legend enlarged approximately in proportion to the outside dimensions.

11. Where any part of the roadway is obstructed or closed by work activities or incidents, advance warning signs should be installed to alert road users well in advance of these obstructions or restrictions.

12. Where road users include pedestrians, the provision of supplemental audible information or detectable barriers or barricades should be provided for people with vision disabilities.

Support

13. Detectable barriers or barricades communicate very clearly to pedestrians who have vision disabilities that they can no longer proceed in the direction that they are traveling.

Option

14. Advance warning signs may be used singly or in combination.

15. Where distances are not displayed on warning signs as part of the message, a supplemental plaque with the distance legend may be mounted immediately below the sign on the same support.

16. The NO SHOULDER (W8-23) sign (see Figure 6H-1) may be used where no earth, gravel or paved shoulders are available for vehicles to pull off the roadway.

Support

17. Some of the California warning signs used in TTC zones are shown in Figure 6H-1(CA) and Table 6H-1(CA).

§6H.02 Position of Advance Warning Signs

Guidance

01. Where highway conditions permit, warning signs should be placed in advance of the transition and activity areas at varying distances depending on roadway type, condition, and posted speed. Table 6B-1 contains information regarding the spacing of advance warning signs. Where a series of two or more advance warning signs is used, the closest sign to the transition and activity areas should be placed approximately 100 feet for low-speed urban streets to 1,000 feet or more for freeways and expressways.

02. Where multiple advance warning signs are needed on the approach to a transition and activity area, the ROAD WORK AHEAD (W20-1) sign should be the first advance warning sign encountered by road users.

Support

03. Various conditions, such as limited sight distance or obstructions that might require a driver to reduce speed or stop, might require additional advance warning signs.

Option

04. As an alternative to a specific distance on advance warning signs, the word AHEAD may be used. Support:

05. At TTC zones on lightly-traveled roads, all of the advance warning signs prescribed for major construction might not be needed.

Option

06. Utility work, maintenance, or minor construction can occur within the TTC zone limits of a major construction project, and additional warning signs may be needed.

Guidance

07. Utility, maintenance, and minor construction signing and TTC should be coordinated with appropriate authorities so that road users are not confused or misled by the additional TTC devices.

§6H.03 ROAD (STREET) WORK Sign (W20-1)

Guidance

01. The ROAD (STREET) WORK (W20-1) sign (see Figure 6H-1), which serves as a general warning of obstructions or restrictions, should be located in advance of the work space or any detour, on the road where the work is taking place.

02. Where traffic can enter a TTC zone from a crossroad or a major (high-volume) driveway, an advance warning sign should be used on the crossroad or major driveway.

Option

03. The legend STREET may be substituted for ROAD and the distance legend may be either XX FEET, XX MILES, or

04. The RAMP WORK AHEAD (C23(CA)) sign (see Figure 6H-1(CA)) may be substituted for the W20-1 sign where applicable.

05. The ROAD (STREET) WORK Informational plaque (C23B(CA)) (refer to Figure 6H-1(CA)) may be used with the ROAD (STREET) WORK (W20-1) sign.

Standard

06. The message displayed on the ROAD (STREET) WORK Informational plaque (C23B(CA)) shall be worded in terms common to motorists, as shown in examples below. The height and width of the plate will vary according to the lettering size and message. The width of the plate shall not exceed the overall width of the W20-1 sign.

Support

07. Following are some example messages:

  • A. BRIDGE REPLACEMENT
  • B. BRIDGE WIDENING
  • C. BRIDGE REPAIR
  • D. CURVE IMPROVEMENT
  • E. HIGHWAY REALIGNMENT
  • F. HIGHWAY WIDENING
  • G. HIGHWAY WIDENING AND PAVING
  • H. HIGHWAY REHABILITATION
  • I. STORM REPAIR
  • J. PAVING
  • K. SIGNING IMPROVEMENT
  • L. PAVEMENT MAINTENANCE
  • M. SAFETY IMPROVEMENT

Guidance

08. The SPECIAL EVENT AHEAD (SC5(CA)) sign (refer to Figure 6H-1(CA)) should be used in lieu of the ROAD (STREET) WORK (W20-1) sign for special events, such as bike races, movie filming, etc., where the event is on the travel way or close enough or of such a nature as to have a potential effect on motorists, bicyclists and pedestrians.

§6H.04 DETOUR Sign (W20-2)

Standard

01. The DETOUR (W20-2) sign (see Figure 6H-1) should shall be used in advance of a road user detour over a different roadway or route. Refer to CVC § 21363 for detour signs.

Option

01. The distance legend may be either XX FEET, XX MILES, or AHEAD.

§6H.05 ROAD (STREET) CLOSED Sign (W20-3)

Guidance

01. The ROAD (STREET) CLOSED (W20-3) sign (see Figure 6H-1) should be used in advance of the point where a highway is closed to all road users, or to all but local road users.

Option

02. The legend STREET may be substituted for ROAD and the distance legend may be either XX FEET, XX MILES, or

§6H.06 ONE LANE ROAD Sign (W20-4)

Standard

01. The ONE LANE ROAD (W20-4) sign (see Figure 6H-1) shall be used only in advance of that point where motor vehicle traffic in both directions must use a common single lane (see Section 6E.01).

Option

02. The distance legend may be either XX FEET, XX MILES, or AHEAD.

§6H.07 Lane(s) Closed Signs (W20-5, W20-5a, and W9-3)

Standard

01. The Lane(s) Closed sign (see Figure 6H-1) shall be used in advance of that point where one or more through lanes of a multi-lane roadway are closed.

02. For a single lane closure, the Lane Closed (W20-5) sign (see Figure 6H-1) shall use the legend RIGHT (LEFT) LANE CLOSED. Where two or more adjacent lanes are closed, the W20-5a sign (see Figure 6H-1) shall use the legend XX RIGHT (LEFT) LANES CLOSED.

Option

02a. The Lane Closed or LANE(S) CLOSED (W20-5, W20-5a or C20(CA)) sign by itself, or in combination with LEFT (C20A(CA)) sign overlay and/or Numeral (C20B(CA)) sign overlay may be used. (Refer to Figures 6H-1, 6H-1(CA) and 6I-1(CA)).

02b. The LANE CLOSED (C30(CA)) sign (refer to Figure 6H-1(CA)) may be used within a closed lane of a multilane highway as follow-up information to the appropriate advance warning signs. The C30(CA) sign may be repeated at intervals, throughout long lane closures, as a reminder to motorists.

03. The distance legend may be either XX FEET, XX MILES, or AHEAD.

Guidance

04. The Interior Lane Shift (W9-3) sign (see Figure 6H-1) should be used in advance of that point where work occupies an interior lane(s) and approaching motor vehicle traffic is directed to the right or left of the work zone in the lane(s) by using a shifting taper to route traffic around the closed interior lane(s).

Support

05. For moving lane closures on State highways, see Caltrans’ Standard Plan T-16. Refer to Section 1A.05 for information regarding this publication.

06. Do not use the CENTER LANE CLOSED AHEAD (W9-3) sign (refer to Figure 6H-1) for moving lane closures on State highways.

§6H.08 Lane Ends Signs (W4-2 and W9-2a)

Guidance

01. The Lane Ends (W4-2) sign (see Figure 6H-1) may should be used to warn drivers of the reduction in the number of lanes for moving motor vehicle traffic in the direction of travel on a multi-lane roadway.

Guidance

02. The MERGE HERE TAKE TURNS (W9-2a) sign (see Figure 6H-1) should be used to identify the merge point at which vehicles from alternate lanes take turns merging during Late Merge applications (see Section 6N.19).

§6H.09 ON RAMP Plaque (W13-4P)

Guidance

01. When work is being done on a ramp, but the ramp remains open, the ON RAMP (W13-4P) plaque (see Figure 6H-1) should be used to supplement the advance ROAD WORK sign.

Standard

02. The ON RAMP (W13-4P) plaque shall not be used in California due to the potential for conflict if it is used when the work is being done on an off ramp.

§6H.10 RAMP NARROWS Sign (W5-4)

Guidance

01. The RAMP NARROWS (W5-4) sign (see Figure 6H-1) should be used in advance of the point where work on a ramp reduces the normal width of the ramp along a part or all of the ramp.

Option

02. The ROAD NARROWS (W5-1) sign (refer to Figure 6H-1) or NARROW LANE(S) (C12(CA)) sign (refer to Figure 6H-1(CA)), as appropriate, may be used instead of the RAMP NARROWS (W5-4) sign (refer to Figure 6H-1). Refer to Sections 2C.17 and

§6H.11 SLOW TRAFFIC AHEAD Sign (W23-1)

Option

The SLOW TRAFFIC AHEAD (W23-1) sign (see Figure 6H-1) may be used on a shadow vehicle, usually mounted on the rear of the most upstream shadow vehicle, along with other appropriate signs for mobile operations to warn of slow moving work vehicles. A ROAD (STREET) WORK (W20-1) sign may also be used with the SLOW TRAFFIC AHEAD sign.

§6H.12 EXIT OPEN and EXIT CLOSED Signs (E5-2 and E5-2a)

Option

01. An EXIT OPEN (E5-2) or EXIT CLOSED (E5-2a) sign (see Figure 6H-1) may be used to supplement other warning signs where work is being conducted in the vicinity of an exit ramp and where the exit maneuver for vehicular traffic using the ramp is different from the normal condition.

Support

02. Refer to FHWA’s List of Known Errors for error in Paragraph 1. Refer to Section 1A.04 for more details.

§6H.13 EXIT ONLY Sign (E5-3)

Option

An EXIT ONLY (E5-3) sign (see Figure 6H-1) may be used to supplement other warning signs where work is being conducted in the vicinity of an exit ramp and where the exit maneuver for vehicular traffic using the ramp is different from the normal condition.

§6H.14 NEW TRAFFIC PATTERN AHEAD Sign (W23-2)

Option

01. A NEW TRAFFIC PATTERN AHEAD (W23-2) sign (see Figure 6H-1) may be used on the approach to an intersection or along a section of roadway to provide advance warning of a change in traffic patterns, such as revised lane usage, roadway geometry, or signal phasing.

Guidance

02. To retain its effectiveness, the W23-2 sign should be displayed for up to 2 weeks, and then it should be covered or removed until it is needed again.

§6H.15 Flagger Signs (W20-7 and W20-7a)

Guidance

01. The Flagger (W20-7) sign (see Figure 6H-1) should be used in advance of any point where a flagger is stationed to control road users.

Option

02. A distance legend may be displayed on a supplemental plaque below the Flagger sign. The sign may be used with appropriate legends or in conjunction with other warning signs, such as the BE PREPARED TO STOP (W3-4) sign (see Figure 6H-1).

03. The FLAGGER (W20-7a) word message sign with a distance legend may be substituted for the Flagger (W20-7) sign.

§6H.16 Two-Way Traffic Sign (W6-3)

Guidance

01. When one roadway of a normally-divided highway is closed, with two-way vehicular traffic maintained on the other roadway, the Two-Way Traffic (W6-3) sign (see Figure 6H-1) should be used at the beginning of the two-way vehicular traffic section and at intervals to remind road users of opposing vehicular traffic.

02. The Two-Way Traffic (W6-3) sign should also be used at locations where motorists could perceive that they are on a one-way roadway when, in fact, they are on a two lane, two-way highway.

Support

03. Following are some typical situations:

  • A. Construction sites where a two-lane highway is being converted to a freeway or an expressway.
  • B. Two-lane, two-way highways where ultimate freeway or expressway right-of-way has been purchased and grading for the full width has been completed.
  • C. Two-lane, two-way highways following long sections of multi-lane freeway or expressway.
  • D. Lane-shift as shown in Figure 6P-102(CA).

§6H.17 Narrow Two-Way Traffic Sign (W6-4)

Standard

01. The Narrow Two-Way Traffic (W6-4) sign (see Figure 6H-1) shall be an upright, retroreflective orangecolored sign placed on a flexible support and sized at least 12 inches wide by 18 inches high.

Support

02. The Narrow Two-Way Traffic (W6-4) sign is intended for mounting only on a flexible support in a series along the center line to separate opposing vehicular traffic on a two-lane, two-way operation.

Standard

03. Narrow Two-Way Traffic signs shall not be placed within pedestrian crossings.

§6H.18 Workers Signs (W21-1 and W21-1a)

Option

01. A Workers (W21-1) sign (see Figure 6H-1) may be used to alert road users of workers in or near the roadway.

Guidance

02. In the absence of other warning devices, a Workers sign should be used when workers are in the roadway.

Option

03. The WORKERS (W21-1a) word message sign may be used as an alternate to the Workers (W21-1) symbol sign.

§6H.19 FRESH OIL (TAR) Sign (W21-2)

Guidance

The FRESH OIL (TAR) (W21-2) sign (see Figure 6H-1) should be used to warn road users of the surface treatment.

§6H.20 ROAD MACHINERY AHEAD Sign (W21-3)

Option

The ROAD MACHINERY AHEAD (W21-3) sign (see Figure 6H-1) may be used to warn of machinery operating in or adjacent to the roadway.

§6H.21 Motorized Traffic Signs (W8-6 and W11-10)

Option

01. Motorized Traffic (W8-6 and W11-10 or C44(CA)) signs (refer to Figure 6H-1 and Figure 6H-1(CA)) may be used to alert road users to locations where unexpected travel on the roadway or entries into or departures from the roadway by construction vehicles might occur. The TRUCK CROSSING (W8-6) or TRUCKS ENTERING EXITING (C44(CA)) word message sign may be used as an alternate to the Truck (W11-10) symbol sign (see Figure 6H-1) where there is an established construction vehicle crossing, entrance, or exit of the roadway.

Support

02. These locations might be relatively confined or might occur randomly over a segment of roadway.

§6H.22 Shoulder Work Signs (W21-5, W21-5a, and W21-5b)

Support

01. Shoulder Work signs (see Figure 6H-1 and Figure 6H-1(CA)) warn of maintenance, reconstruction, or utility operations on the highway shoulder where the roadway is unobstructed.

Standard

02. The Shoulder Work sign shall have the legend SHOULDER WORK (W21-5), RIGHT (LEFT) SHOULDER CLOSED (W21-5a), or RIGHT (LEFT) SHOULDER CLOSED XX FT or AHEAD (W21- 5b), or SHOULDER WORK AHEAD (C24(CA)), or SHOULDER CLOSED (C30A(CA)).

Option

03. The Shoulder Work sign may be used in advance of the point on a non-limited access highway where there is shoulder work. It may be used singly or in combination with a ROAD WORK NEXT XX MILES or ROAD WORK AHEAD sign.

Guidance

04. On freeways and expressways, the RIGHT (LEFT) SHOULDER CLOSED XX FT or AHEAD (W21- 5b) sign followed by RIGHT (LEFT) SHOULDER CLOSED (W21-5a) sign should be used in advance of the point where the shoulder work occurs and should be preceded by a ROAD WORK AHEAD sign.

Option

05. The SHOULDER WORK AHEAD (C24(CA)) sign may be used in advance of the point where shoulder work or utility operations involve the shoulder but the roadway is unobstructed.

06. The SHOULDER CLOSED (C30A(CA)) sign may be used within a shoulder area that has been closed due to work near the traveled way. The C30A(CA) sign is supplemental to appropriate advance warning signs.

§6H.23 SURVEY CREW Sign (W21-6)

Guidance

The SURVEY CREW (W21-6) sign (see Figure 6H-1) should be used to warn of surveying crews working in or adjacent to the roadway.

§6H.24 UTILITY WORK Sign (W21-7)

Option

01. The UTILITY WORK (W21-7) sign (see Figure 6H-1) may be used as an alternate to the ROAD (STREET) WORK (W20-1) sign for utility operations on or adjacent to a highway.

Support

02. Typical examples of where the UTILITY WORK sign is used appear in Figures 6P-4, 6P-6, 6P-10, 6P-15, 6P-18, 6P-21, 6P-22, 6P-26, and 6P-33.

Option

03. The distance legend may be either XX FEET, XX MILES, or AHEAD.

§6H.25 Signs for Blasting Areas

Support

01. Radio-Frequency (RF) energy can cause the premature firing of electric detonators (blasting caps) used in TTC zones.

Standard

02. Road users shall be warned where blasting operations occur. A sequence of signs shall be prominently displayed to warn all road users of blasting operations and to direct operators of mobile radio equipment, including cellular telephones, to turn off transmitters in a blasting area. These signs shall be covered or removed when there are no explosives in the area or the area is otherwise secured.

03. The BLASTING ZONE AHEAD (W22-1) sign (see Figure 6H-1) shall be used in advance of any TTC zone where explosives are being used. The TURN OFF 2-WAY RADIO AND CELL PHONE (R22-2) and END BLASTING ZONE (W22-3) signs shall be used in sequence with this sign.

04. The TURN OFF 2-WAY RADIO AND CELL PHONE (R22-2) sign (see Section 6G.11 and Figure 6G-1) shall follow the BLASTING ZONE AHEAD (W22-1) sign and shall be placed at least 1,000 feet before the beginning of the blasting zone.

05. The END BLASTING ZONE (W22-3) sign (see Figure 6H-1) shall be placed a minimum of 1,000 feet past the blasting zone.

Option

06. The END BLASTING ZONE sign may be placed either with or preceding the END ROAD WORK sign.

§6H.26 Shoulder Signs and Plaque (W8-4, W8-9, W8-17, and W8-17P)

Option

01. The SOFT SHOULDER (W8-4) sign (see Figure 6H-1) may be used to warn of a soft shoulder condition.

02. The LOW SHOULDER (W8-9) sign (see Figure 6H-1) may be used to warn of a shoulder condition where there is an elevation difference of 3 inches or less between the shoulder and the travel lane.

Guidance

03. The Shoulder Drop Off (W8-17) sign (see Figure 6H-1) should be used when an unprotected shoulder drop-off, adjacent to the travel lane, exceeds 3 inches in depth for a continuous length along the roadway, based on engineering judgment.

Option

04. A SHOULDER DROP-OFF (W8-17P) supplemental plaque (see Figure 6H-1) may be mounted below the W8-17 sign.

05. The black on orange background LOW SHOULDER (W8-9) sign (refer to Figure 6H-1) may be used on State highways to warn of a shoulder condition where there is an elevation difference of less than 3 inches between the shoulder and the travel lane.

§6H.27 UNEVEN LANES Sign (W8-11)

Guidance

01. The UNEVEN LANES (W8-11) sign (see Figure 6H-1) should be used during operations that create a difference in elevation between adjacent lanes that are open to travel.

02. The UNEVEN PAVEMENT (C46(CA)) sign (refer to Figure 6H-1(CA)) should be used during operations that create a difference in elevation in the pavement that is not along a lane line.

Support

03. Uneven pavement conditions include elevation difference adjacent to lanes but not at the lane line; between a vehicle lane and a bicycle lane or an unmarked shoulder; and a step in any direction in the pavement. A step is defined as a ridge in the pavement, such as that which might exist between the pavement and a concrete gutter or manhole cover; or that might exist between two pavement blankets when the top level does not extend to the edge of the roadway.

Option

04. In situations where there is a need to warn bicyclists or other road users of the uneven pavement condition the UNEVEN PAVEMENT (C46P(CA)) plaque (refer to Figure 6H-1(CA)) may be used.

Standard

05. A C46P(CA) plaque shall not be used alone. If a C46P(CA) plaque is used, it shall be mounted below either a Vehicular Traffic Warning sign (refer to Section 2C.54) or a Non-Vehicular Warning sign (refer to Section 2C.55). The background color of the C46P(CA) plaque shall match the background color of the warning sign with which it is displayed.

Option

06. When warning is intended to be directed primarily to motorcyclists, use of the UNEVEN LANES (W8-11) sign or UNEVEN PAVEMENT (C46(CA)) sign with motorcycle plaque (W8-15aP) (refer to Figure 6H-1 and Figure 6H-1(CA)) may be considered.

Support

07. Refer to Table 6H-101(CA) for pavement surface tolerances for each road user group.

§6H.28 STEEL PLATE AHEAD Sign (W8-24)

Option

A STEEL PLATE AHEAD (W8-24) sign (see Figure 6H-1) may be used to warn road users that the presence of a temporary steel plate(s) might make the road surface uneven and might create slippery conditions during wet weather.

§6H.29 NO CENTER LINE Sign (W8-12)

Guidance

01. The NO CENTER LINE (W8-12) sign (see Figure 6H-1) should be used when the work obliterates the center line pavement markings and when temporary pavement centerline markings are not provided. This sign should be placed at the beginning of the TTC zone and repeated at 2-mile intervals in long TTC zones.

Support

02. Section 6J.02 contains information regarding temporary markings.

Standard

03. The NO CENTER LINE (W8-12) sign shall not be used on State highways. Whenever construction or maintenance work causes obliteration of center stripe, temporary or permanent center stripe shall be in place prior to opening the State highway to public traffic.

§6H.30 Reverse Curve Signs (W1-4 Series)

Guidance

01. In order to give road users advance notice of a lane shift, a Reverse Curve (W1-4, W1-4b, or W1-4c) sign (see Figure 6H-1) should be used when a lane (or lanes) is being shifted to the left or right. If the design speed of the curves is 30 mph or less, a Reverse Turn (W1-3) sign should be used.

Standard

02. If a Reverse Curve (or Turn) sign is used, the direction of the reverse curve (or turn) shall be appropriately illustrated. Except as provided in Paragraph 3 of this Section, the number of lanes illustrated on the sign shall be the same as the number of through lanes available to road users.

Option

03. Where two or more lanes are being shifted, a W1-4 (or W1-3) sign with an ALL LANES (W24-1cP) plaque (see Figure 6H-1) may be used instead of a sign that illustrates the number of lanes.

04. Where more than three lanes are being shifted, the Reverse Curve (or Turn) sign may be rectangular.

§6H.31 Double Reverse Curve Signs (W24-1 Series)

Option

01. The Double Reverse Curve (W24-1, W24-1a, or W24-1b) sign (see Figure 6H-1) may be used where the tangent distance between two reverse curves is less than 600 feet, thus making it difficult for a second Reverse Curve (W1-4 series) sign to be placed between the curves. If the design speed of the curves is 30 mph or less, Double Reverse Turn signs may be used.

Standard

02. If a Double Reverse Curve (or Turn) sign is used, the direction of the double reverse curve (or turn) shall be appropriately illustrated. Except as provided in Paragraph 3 of this Section, the number of lanes illustrated on the sign shall be the same as the number of through lanes available to road users.

Option

03. Where two or more lanes are being shifted, a W24-1 (or Double Reverse Turn sign showing one lane) sign with an ALL LANES (W24-1cP) plaque (see Figure 6H-1) may be used instead of a sign that illustrates the number of lanes.

04. Where more than three lanes are being shifted, the Double Reverse Curve (or Turn) sign may be rectangular.

§6H.32 Advisory Speed Plaque (W13-1P)

Option

01. In combination with a warning sign, an Advisory Speed (W13-1P) plaque (see Figure 6H-1) may be used to indicate a recommended speed through the TTC zone.

Standard

02. The Advisory Speed plaque shall not be used in conjunction with any sign other than a warning sign, nor shall it be used alone. When used with orange TTC zone signs, this plaque shall have a black legend and border on an orange background. The plaque shall be at least 24 x 24 inches in size when used with a sign that is 36 x 36 inches or larger. Except in emergencies, an Advisory Speed plaque shall not be mounted until the recommended speed is determined by the highway agency.

Support

02a. Refer to FHWA’s List of Known Errors for error in Paragraph 2. Refer to Section 1A.04 for more details.

03. Warning signs with advisory speed plaques (see Section 2C.59) inform drivers of the recommended operating speed based on temporary conditions within a TTC zone. Examples include narrow lanes, temporary diversion (reverse curves), lane shifts, sight distance restrictions, rough road surface, bumps, low/no shoulder, workers on foot, work vehicles or equipment close to the open travel lane, or other conditions that indicate the need for reduced speed.

04. AASHTO and ITE design documents contain established engineering practices for the determination of the recommended advisory speeds for horizontal curves or locations with limited sight distance.

§6H.33 Supplementary Distance Plaque (W7-3aP)

Option

01. In combination with a warning sign, a Supplementary Distance (W7-3aP) plaque (see Figure 6H-1) with the legend NEXT XX MILES may be used to indicate the length of highway over which a work activity is being conducted, or over which a condition exists in the TTC zone.

02. In long TTC zones, Supplementary Distance plaques with the legend NEXT XX MILES may be placed in combination with warning signs at regular intervals within the zone to indicate the remaining length of highway over which the TTC work activity or condition exists.

Standard

03. The Supplementary Distance plaque with the legend NEXT XX MILES shall not be used in conjunction with any sign other than a warning sign, nor shall it be used alone. When used with orange TTC zone signs, this plaque shall have a black legend and border on an orange background. The plaque shall be at least 30 x 24 inches in size when used with a sign that is 36 x 36 inches or larger.

Guidance

04. When used in TTC zones, the Supplementary Distance plaque with the legend NEXT XX MILES should be placed below the initial warning sign designating that, within the approaching zone, a temporary work activity or condition exists.

§6H.34 Motorcycle Plaque (W8-15P)

Support

Refer to FHWA’s List of Known Errors for error in Section title. Refer to Section 1A.04 for more details.

Option

01. A Motorcycle (W8-15P) plaque (see Figure 6H-1) may be mounted below a LOOSE GRAVEL (W8- 7) sign, an UNEVEN LANES (W8-11) sign, an UNEVEN PAVEMENT (C46(CA)) sign (see Figure 6H-1(CA)), a GROOVED PAVEMENT (W8-15) sign, a METAL BRIDGE DECK (W8-16) sign, or a STEEL PLATE AHEAD (W8-24) sign if the warning is intended to be directed primarily to motorcyclists.

Support

02. Refer to FHWA’s List of Known Errors for error in Paragraph 1. Refer to Section 1A.04 for more details.

§6H.35 ROAD WORK NEXT XX MILES Sign (G20-1)

Guidance

01. The ROAD WORK NEXT XX MILES (G20-1) sign (see Figure 6H-1) should be installed in advance of TTC zones that are more than 2 miles in length.

Option

02. The ROAD WORK NEXT XX MILES sign may be mounted on a Type 3 Barricade. The sign may also be used for TTC zones of shorter length.

Standard

03. The distance displayed on the ROAD WORK NEXT XX MILES sign shall be stated to the nearest whole mile.

§6H.36 END ROAD WORK Sign (G20-2)

Guidance

01. When used, the END ROAD WORK (G20-2) sign (see Figure 6H-1) should be placed near the downstream end of the termination area, as determined by engineering judgment.

Option

02. The END ROAD WORK sign may be installed on the back of a warning sign facing the opposite direction of road users or on the back of a Type 3 Barricade.

03. The END ROAD WORK (G20-2) sign may be omitted if the end of the work zone is obvious to motorists or falls within a larger project’s limits.

Support

04. Conditions could be such that posting of END ROAD WORK (G20-2) signs is not helpful. For example, they can be omitted if other TTC zones begin within 1 mile of the end of the workspace in rural areas, or about 0.25 miles within urban areas. For normal daytime maintenance operations, the G20-2 sign is optional.

§6H.37 PILOT CAR FOLLOW ME Sign (G20-4)

Standard

The PILOT CAR FOLLOW ME (G20-4) sign (see Figure 6H-1) shall be mounted in a conspicuous position on the top or on the rear of a vehicle used for guiding one-way vehicular traffic through or around a TTC zone (see Section 6E.04).

§6H.38 Other Warning Signs

Option

01. Advance warning signs may be used by themselves or with other advance warning signs.

02. Besides the warning signs specifically related to TTC zones, several other warning signs in Part 2 may apply in TTC zones.

03. Word message warning signs other than those classified and specified in this Manual and the “Standard Highway Signs” publication (see Section 1A.05) may be developed and used based on engineering judgment to warn of special conditions in TTC zones.

Standard

04. Except as provided in Sections 6F.01 and 6H.01, other warning signs that are used in TTC zones shall have black legends and borders on an orange background.

Guidance

05. Other warning signs should comply with the general requirements of color, shape, and alphabet size and series. The sign message should be brief, legible, and clear.

§6H.101(CA) LOOSE GRAVEL Sign (W8-7)

Guidance

The LOOSE GRAVEL (W8-7) sign (refer to Figure 6H-1) should be used on chip seal jobs or other areas to warn motorists that there is loose gravel on the roadway.

Standard

02. When used, the W8-7 sign shall be placed at the beginning of work and at maximum 2000 feet intervals.

Option

03. When warning is intended to be directed primarily to motorcyclists, use of the W8-7 sign with motorcycle plaque (W8-15aP) may be considered.

04. The Advisory Speed (W13-1P) plaque (refer to Figure 6H-1) may be used in combination with the W8-7 sign to indicate the need

01. to decrease speed at a particular location. Refer to Section 6B.01.

Guidance

05. The advisory speed should be reasonable or prudent, considering weather, visibility, traffic, surface condition and width of the roadway.

Standard

06. On highways with speed limits of 40 mph or higher for seal coat projects, the W13-1P (35 mph or lower) plaque shall be used to supplement the W8-7 sign during placement and/or brooming of screenings.

§6H.102(CA) NARROW LANE(S) Sign (C12(CA))

Option

01. The NARROW LANE(S) (C12(CA)) sign (refer to Figure 6H-1(CA)) may be used, when appropriate, to warn the approaching motorist of a narrow lane condition.

Guidance

02. When used, the C12(CA) sign should be used in conjunction with an Advisory Speed (W13-1P) plaque (refer to Figure 6H-1). Refer to Section 6B.01.

§6H.103(CA) OPEN TRENCH Sign (C27(CA))

Standard

01. The OPEN TRENCH (C27(CA)) sign (see Figure 6H-1(CA)) shall be used in advance of open trenches in/or adjacent to roadway.

02. The edge of the traveled way shall be defined by edge line delineation consisting of appropriate markers or striping. Edge line delineation shall be white when located on the right of traffic and yellow when located on the left of traffic.

Guidance

03. Trenches in excess of 0.15 feet in depth but not exceeding 0.25 feet in depth that are less than 8 feet from the edge of traveled way should be identified by LOW SHOULDER (W8-9) signs (refer to Figure 6H-1) set in the trench adjacent to the edge of pavement at intervals not to exceed every 2,000 feet.

Option

04. Portable delineators may be placed at intervals not to exceed 100 feet in lieu of edge line delineation.

Standard

05. Trenches in excess of 0.25 feet but less than 2.5 feet in depth that are less than 8 feet from the edge of traveled way shall be identified by alternating C27(CA) and NO SHOULDER (W8-23) signs (refer to Figure 6H-1 and Figure 6H-1(CA)) set in the trench at intervals not to exceed 2,000 feet.

Guidance

06. Channelizers (CA) or portable delineators should be placed 2 feet to 6 feet outside of the edge line at 100 feet intervals for the conditions described above.

07. Trenches in excess of 0.25 feet in depth but not exceeding 2.5 feet in depth that are 8 feet to 15 feet from the edge of traveled way should be identified by C27(CA) signs set in the trench at intervals not to exceed every 2,000 feet. Portable delineators should be placed at 200 feet intervals within 2 feet from the edge of the trench and at 100 feet intervals for edge conditions exceeding 0.5 feet in depth.

08. Trenches in excess of 0.5 feet in depth but not exceeding 2.5 feet in depth that are more than 15 feet from the edge of traveled way at locations where a recovery area was available prior to construction should be identified by placing delineators at 200 feet intervals within 2 feet from the edge of the trench and by placing C27(CA) signs in the trench at intervals not to exceed 2,000 feet.

Standard

09. Signing for trenches in excess of 2.5 feet in depth shall be based upon engineering judgment or studies (as noted in Section 1D.03) to ensure proper visibility of barricades and signing.

Support

10. Refer to Tables 6K-101(CA) and 6B-1.

§6H.104(CA) Object Markers

Standard

When used in work zones, the OM1-3 object markers (refer to Figure 6H-101(CA)) shall have an orange or fluorescent orange retroreflective background. When used in work zones, the Type OM3-L, OM3-R and OM3-C object marker (refer to Figure 6H-101(CA)) shall have alternating retroreflective orange and white stripes.

Support

03. Figure 6H-101(CA) shows examples of object markers in TTC zones.

04. Refer to Chapter 2C for more details.

§6H.105(CA) Slow For The Cone Zone (SC19(CA) and SC20(CA)) Signs

Option

01. The Slow For The Cone Zone (SC19(CA)) and SLOW FOR THE CONE ZONE (SC20(CA)) signs (refer to Figures 6H-1(CA), 6P32, 6P-33, and 6P-36 may be used to remind motorists to slow down when entering a temporary traffic control (TTC) zone to improve worker and road user safety.

02. If used, SC19(CA) and/or SC20(CA) signs may be used within the advance warning area, transition area, or activity area of a TTC zone.

03. A pictograph may be used on the SC19(CA) sign to identify a governmental jurisdiction, an area of jurisdiction, a governmental agency, a military base or branch of service, a governmental-approved university or college, or a governmental-approved institution.

Standard

04. If a pictograph is used on the SC19(CA) sign, the maximum dimension (height or width) of a pictograph shall not exceed two times the letter height of the largest legend used on the sign.

§6H.106(CA) FRESH CONCRETE Sign (C43(CA))

Option

01. The FRESH CONCRETE (C43(CA)) sign (refer to Figure 6H-1(CA)) may be used to warn road users of the surface treatment.

Standard

02. When used, the FRESH CONCRETE (C43(CA)) sign shall be placed at the beginning of the pavement work area.

Guidance

03. The FRESH CONCRETE (C43(CA)) sign should remain in place during the entire curing period.

§6H.107(CA) CAUTION FREQUENT STOPPING AND BACKING STAY BACK 100 FEET Sign (SC21(CA))

Option

For mobile operations, CAUTION FREQUENT STOPPING AND BACKING STAY BACK 100 FEET (SC21(CA)) sign (refer to Figure 6H-1(CA)) may be mounted on a work vehicle to warn road users and workers of the frequent stopping and backing maneuvers made by the vehicle.

Figure 6H-1. Warning Signs and Plaques in Temporary Traffic Control Zones (Sheet 1 of 4)
Figure 6H-1. Warning Signs and Plaques in Temporary Traffic Control Zones (Sheet 1 of 4)

Signs shown: W1-1, W1-2, W1-3, W1-4, W1-4b, W1-4c, W1-6, W1-8, W3-1, W3-2, W3-3, W3-4, W3-5, W3-5a, W4-1, W4-2, W4-3, W4-5, W4-5aP, W4-6, W5-1, W5-2, W5-3, W5-4, W6-1, W6-2, W6-3, W6-4, W7-1, W7-3aP, W8-1

Figure 6H-1. Warning Signs and Plaques in Temporary Traffic Control Zones (Sheet 2 of 4)
Figure 6H-1. Warning Signs and Plaques in Temporary Traffic Control Zones (Sheet 2 of 4)

Signs shown: W8-2, W8-3, W8-4, W8-5, W8-6, W8-7, W8-8, W8-9, W8-11, W8-12, W8-15, W8-17, W8-15aP, W8-17P, W8-14, W8-16, W8-18, W8-23, W8-24, W8-25, W9-1, W9-2a, W9-3, W9-5a, W11-10, W12-1, W12-2, W13-1P

Figure 6H-1. Warning Signs and Plaques in Temporary Traffic Control Zones (Sheet 3 of 4)
Figure 6H-1. Warning Signs and Plaques in Temporary Traffic Control Zones (Sheet 3 of 4)

Signs shown: W13-4P, W14-3, W20-1, W20-1b, W20-2, W20-2a, W20-3, W20-3a, W20-4, W20-5, W20-7, W20-5a, W20-5b, W21-1, W21-1a, W16-2P, W21-2, W21-3, W21-4, W21-5, W21-5a, W21-5b, W21-6, W21-7, W21-8, W22-1, W20-7a

Figure 6H-1. Warning Signs and Plaques in Temporary Traffic Control Zones (Sheet 4 of 4)
Figure 6H-1. Warning Signs and Plaques in Temporary Traffic Control Zones (Sheet 4 of 4)

Signs shown: W24-1, W24-1cP, W22-3, W23-1, W23-2, W24-1a, W24-1b, G20-1, G20-2, G20-4

Figure 6H-1(CA). California Warning Signs and Plaques in Temporary Traffic Control Zones
Figure 6H-1(CA). California Warning Signs and Plaques in Temporary Traffic Control Zones
Figure 6H-101(CA). Examples of Object Markers in Temporary Traffic Control Zones Object Marker (OM1-3)
Figure 6H-101(CA). Examples of Object Markers in Temporary Traffic Control Zones Object Marker (OM1-3)

Signs shown: OM1-3

Table 6H-1. Temporary Traffic Control Zone Warning Sign and Plaque Sizes (Sheet 1 of 2)

Sign or PlaqueSign DesignationSectionConventional RoadFreeway or ExpresswayMinimum
Turn and Curve SignsW1-1,2,3,46H.0136 x 3648 x 4830 x 30
Reverse Curve (2 or more lanes)W1-4b,4c6H.3036 x 3648 x 4830 x 30
Large Arrow (1-direction)W1-66H.0148 x 2460 x 30—
Chevron AlignmentW1-86H.0118 x 2430 x 36—
Stop AheadW3-16H.0136 x 3648 x 4830 x 30
Yield AheadW3-26H.0136 x 3648 x 4830 x 30
Signal AheadW3-36H.0136 x 3648 x 4830 x 30
Be Prepared to StopW3-46H.0136 x 3648 x 4830 x 30
Reduced Speed Limit AheadW3-56H.0136 x 3648 x 4830 x 30
XX MPH Speed Zone AheadW3-5a6H.0136 x 3648 x 4830 x 30
Merging TrafficW4-1,56H.0136 x 3648 x 4836 x 36
Lane EndsW4-26H.0836 x 3648 x 4830 x 30
Added LaneW4-3,66H.0136 x 3648 x 4830 x 30
No Merge Area (plaque)W4-5aP6H.0118 x 2424 x 30—
Road NarrowsW5-16H.0136 x 3648 x 4830 x 30
Narrow BridgeW5-26H.0136 x 3648 x 4830 x 30
One Lane BridgeW5-36H.0136 x 3648 x 4830 x 30
Ramp NarrowsW5-46H.1036 x 3648 x 4830 x 30
Divided HighwayW6-16H.0136 x 3648 x 4830 x 30
Divided Highway EndsW6-26H.0136 x 3648 x 4830 x 30
Two-Way TrafficW6-36H.1636 x 3648 x 4830 x 30
Narrow Two-Way TrafficW6-46H.1712 x 1812 x 18—
HillW7-16H.0136 x 3648 x 4830 x 30
Next XX Miles (plaque)W7-3aP6H.3324 x 1836 x 30—
BumpW8-16H.0136 x 3648 x 4824 x 24
DipW8-26H.0136 x 3648 x 4824 x 24
Pavement EndsW8-36H.0136 x 3648 x 4830 x 30
Soft ShoulderW8-46H.2636 x 3648 x 4830 x 30
Slippery When WetW8-56H.0136 x 3648 x 4830 x 30
Truck CrossingW8-66H.2136 x 3648 x 4830 x 30
Loose GravelW8-76H.0136 x 3648 x 4830 x 30
Rough RoadW8-86H.0136 x 3648 x 4824 x 24
Low ShoulderW8-96H.2636 x 3648 x 4824 x 24
Uneven LanesW8-116H.2736 x 3648 x 4830 x 30
No Center LineW8-126H.2936 x 3648 x 4830 x 30
Fallen RocksW8-146H.0136 x 3648 x 4830 x 30
Grooved PavementW8-156H.0136 x 3648 x 4830 x 30
Motorcycle (plaque)W8-15aP6H.3424 x 1830 x 24—
Metal Bridge DeckW8-166H.3436 x 3648 x 4830 x 30
Shoulder Drop Off (symbol)W8-176H.2636 x 3648 x 4830 x 30
Shoulder Drop-Off (plaque)W8-17P6H.2624 x 1830 x 24—
Road May FloodW8-186H.0136 x 3648 x 4824 x 24
No ShoulderW8-236H.0136 x 3648 x 4830 x 30
Steel Plate AheadW8-246H.2836 x 3648 x 4830 x 30
Shoulder EndsW8-256H.0136 x 3648 x 4830 x 30
Lane EndsW9-1,26H.0136 x 3648 x 4830 x 30
Merge Here Take TurnsW9-2a6N.1936 x 4836 x 48—
Interior Lane Shift AheadW9-36H.0736 x 3648 x 4830 x 30

Table 6H-1. Temporary Traffic Control Zone Warning Sign and Plaque Sizes (Sheet 2 of 2)

Sign or PlaqueSign DesignationSectionConventional RoadFreeway or ExpresswayMinimum
Bicycles MergingW9-5a6P.0130 x 30—18 x 18
Grade Crossing Advance WarningW10-16H.0136 dia.48 Dia.—
TruckW11-106H.2136 x 3648 x 4824 x 24
Double ArrowW12-16H.0130 x 3036 x 36—
Low ClearanceW12-26H.0136 x 3648 x 4830 x 30
Advisory Speed (plaque)W13-1P6H.3218 x 1824 x 2418 x 18
On Ramp (plaque)W13-4P6H.0936 x 3636 x 36—
No Passing Zone (pennant)W14-36H.0148 x 48 x 3664 x 64 x 4840 x 40 x 30
XX Feet (2-line plaque)W16-2P6H.0124 x 1830 x 24—
Road Work (with distance)W20-16H.0336 x 3648 x 4830 x 30
Path Work (with distance)W20-1b6P.0136 x 36—30 x 30
Detour (with distance)W20-26H.0436 x 3648 x 4830 x 30
Bike Detour (with distance)W20-2a6P.0136 x 36—30 x 30
** Bike Diversion (with distance)W20-2b6P.0136 x 36—30 x 30
Road Closed (with distance)W20-36H.0536 x 3648 x 4830 x 30
Path Closed (with distance)W20-3a6P.0136 x 36—30 x 30
One Lane Road (with distance)W20-46H.0636 x 3648 x 4830 x 30
Lane(s) Closed (with distance)W20-5,5a6H.0736 x 3648 x 4830 x 30
Bike Lane Closed (with distance)W20-5b6P.0136 x 36—30 x 30
Flagger (symbol)W20-76H.1536 x 3648 x 4830 x 30
FlaggerW20-7a6H.1536 x 3648 x 4830 x 30
Slow (on Stop/Slow Paddle)W20-86D.0218 x 18——
WorkersW21-1,1a6H.1836 x 3648 x 4830 x 30
Fresh OilW21-26H.1936 x 3648 x 4830 x 30
Road Machinery AheadW21-36H.2036 x 3648 x 4830 x 30
Slow Moving VehicleW21-46N.0536 x 18——
Shoulder WorkW21-56H.2236 x 3648 x 4830 x 30
Shoulder ClosedW21-5a6H.2236 x 3648 x 4830 x 30
Shoulder Closed (with distance)W21-5b6H.2236 x 3648 x 4830 x 30
Survey CrewW21-66H.2336 x 3648 x 4830 x 30
Utility Work (with distance)W21-76H.2436 x 3648 x 4830 x 30
Mowing AheadW21-86N.0536 x 3648 x 4830 x 30
Blasting Zone AheadW22-16H.2536 x 3648 x 4830 x 30
End Blasting ZoneW22-36H.2542 x 3642 x 3636 x 30
Slow Traffic AheadW23-16H.1154 x 30 48 x 2472 x 42 48 x 2448 x 24 —
New Traffic Pattern AheadW23-26H.1436 x 3648 x 4830 x 30
Double Reverse Curve (1 lane)W24-16H.3136 x 3648 x 4830 x 30
Double Reverse Curve (2 lanes)W24-1a6H.3136 x 3648 x 4830 x 30
Double Reverse Curve (3 lanes)W24-1b6H.3136 x 3648 x 4830 x 30
All Lanes (plaque)W24-1cP6H.3124 x 1830 x 24—
Road Work (Construction) Next XX60 x 3690 x 4836 x 18
G20-16H.35
Miles36 x 1848 x 24—
End Road WorkG20-26H.3636 x 1848 x 24—
Pilot Car Follow MeG20-46H.3736 x 18——

* See Table 2C-1 for minimum size required for signs facing traffic on multi-lane conventional roads

** Refer to FHWA’s List of Known Errors for error in row with the W20-2b sign. Refer to Section 1A.04 for more details.

Notes:

1. Larger signs may be used wherever necessary for greater legibility or emphasis

2. Dimensions are shown in inches and are shown as width x height

Table 6H-1(CA). California Temporary Traffic Control Zone Warning Sign and Plaque Sizes

Sign or PlaqueSign DesignationSectionConventional Road (Minimum)ExpresswayFreewayOversized
NARROW LANE(S)C12(CA)6H.10, 6H.102(CA)36 x 3648 x 4848 x 48---
RAMP CLOSED AHEADC19(CA)6G.10136 x 3648 x 4848 x 48---
RIGHT LANE CLOSED AHEADC20(CA)6H.0736 x 3648 x 4848 x 4872 x 72
RAMP WORK AHEADC23(CA)6H.0336 x 3648 x 4848 x 48---
ROAD (STREET) WORK Informational plaqueC23B(CA)6H.03Var x 18Var x 24Var x 24---
SHOULDER WORK AHEADC24(CA)6H.2230 x 3048 x 4848 x 48---
OPEN TRENCHC27(CA)6H.103(CA)36 x 3648 x 4848 x 48---
LANE CLOSEDC30(CA)6H.0730 x 3048 x 4848 x 48---
SHOULDER CLOSEDC30A(CA)6H.2230 x 3048 x 4848 x 48---
TRAFFIC CONTROL - WAIT AND FOLLOW PILOT CARC37(CA)6E.0436 x 4236 x 42------
TRAFFIC FINES DOUBLED IN WORK ZONESC40A(CA)6G.0836 x 3648 x 4848 x 48---
FRESH CONCRETEC43(CA)6H.106(CA)36 x 3648 x 4848 x 48---
TRUCKS ENTERING EXITINGC44(CA)6H.2136 x 3648 x 4848 x 48---
RUMBLE STRIPSC45(CA)6M.0636 x 3648 x 48------
UNEVEN PAVEMENTC46(CA)6H.2736 x 3648 x 4848 x 48---
UNEVEN PAVEMENT plaqueC46P(CA)6H.2730 x 1836 x 2436 x 24---
SPECIAL EVENT AHEADSC5(CA)6H.0336 x 3648 x 4848 x 48---
Slow For The Cone ZoneSC19(CA)6H.105(CA)54 x 3654 x 3654 x 36114 x 78
SC20(CA)6H.105(CA)42 x 3654 x 4854 x 48---
SLOW FOR THE CONE ZONE
CAUTION FREQUENT STOPPING AND BACKING STAY BACK 100 FEETSC21(CA)6H.107(CA)30 x 4230 x 4230 x 42---
FLOODEDW55(CA)6O.101(CA)30 x 3036 x 3636 x 36---
FLOODING AHEAD TURN AROUND DON’T DROWNW86(CA)6O.101(CA)30 x 24---------
EMERGENCY SCENE AHEADW90(CA)6O.102(CA)36 X 3648 X 4848 X 48---

----72 x 72 --48 x 48

Table 6H-101(CA). Pavement Surface Tolerances*

Direction of TravelSteps**
Bicycles / Motorcycles4 Wheeled Motor Vehicles
Parallel to travelNo more than 3/8” highNo more than 2” high
Perpendicular to travelNo more than 3/4” highNo more than 2” high

Notes:

* Criteria for displaying warning signs. If a step of more than 3” high exists in the pavement, do not open that portion of roadway to traffic.

** Step - A ridge in the pavement, such as that which might exist between the pavement and a concrete gutter or manhole cover; or that might exist between two pavement blankets when the top level does not extend to the edge of the roadway.