SECTION 928 — SHADOW OR ADVANCE WARNING VEHICLE WITH CRASH CUSHION AND FLASHING ARROW BOARD OR CHANGEABLE MESSAGE SIGN 900-71 — SHADOW OR ADVANCE WARNING VEHICLE WITH CRASH CUSHION AND FLASHING ARROW BOARD OR CHANGEABLE MESSAGE SIGN
928.01 Description.
This work includes furnishing, operating, moving, and maintaining a shadow or advance warning vehicle that includes a truck- or trailer-mounted energy-absorbing crash cushion (TMA) and either a truck- or trailer-mounted flashing arrow board (TMFAB) or trailer-mounted changeable message sign (TMCMS).
928.02 Materials.
Shadow or Advance Warning Vehicle. Use a vehicle that meets or exceeds the requirements and recommendations of the TMA manufacturer and that weighs a minimum of 10,000 lb . Ensure that t he vehicle accommodates the mounting of the TMA and the TMFAB or TMCMS at the rear of the vehicle. Ensure that each vehicle includes lighting and markings that conform to the latest Federal and Rhode Island General Laws (RIGL) requirements. Ensure that the appropriate number of first - aid kits and fire extinguishers are furnished with each vehicle conform ing to Section 24-8-4.2 of the RIGL. Truck- or Trailer-Mounted Attenuator (TMA). Use a TMA that has been approved by FHWA as a crashworthy device acceptable for use on the National Highway System. Ensure that each type of TMA furnished and used has been crashed-tested and found to conform to the AASHTO Manual for Assessing Safety Hardware (MASH) and/or NCHRP Report 350, whichever is applicable per the latest FHWA requirements, at the required test level condition listed below, which varies based on the speed limit of the roadway where the TMA will be used. Posted or Statutory Speed Limit (Miles Per Hour) Required Successful Crash-Testing to Test Level (TL) Condition1 40 or less TL-2 or TL-3 45 or greater TL-3 1 As stipulated by the AASHTO Manual for Assessing Safety Hardware or NCHRP Report 350, whichever is applicable per latest FHWA requirements. Furnish and install t he TMA on the shadow/advance warning vehicle according to the TMA manufacturer’s recommendations. Use a TMA that includes lighting and markings that conform to the latest Federal and RIGL requirements. Ensure that t he entire end panel of the TMA that faces oncoming traffic includes chevron pattern markings with alternating non-reflective black and retro-reflective yellow stripes, each stripe a minimum of 4-in. wide and slanted at 45 degrees from vertical, in an inverted “V” form with the inverted “V” located at the center of the TMA end panel.
Part 900 — Incidental Construction and Services August 2025
900-72 SECTION 928 — SHADOW OR ADVANCE WARNING VEHICLE WITH CRASH CUSHION AND FLASHING ARROW BOARD OR CHANGEABLE MESSAGE SIGN Use a combination of the TMA and the shadow/advance warning vehicle that has been selected and furnished as a system conform ing to the TMA manufacturer ’s requirements, and ensure conformance with prior FHWA crashworthiness approval. If necessary, supply the TMA manufacturer with the proposed shadow/advance warning vehicle specifications to confirm that the furnished system complies with these Specifications. Truck- or Trailer-Mounted Flashing Arrow Board (TMFAB). Use a TMFAB that is a 4-ft high by 8-ft wide electronically illuminated arrow panel installed at the rear of the shadow/advance warning vehicle, with the bottom of the panel mounted a minimum of 7 ft above the roadway when in operating mode. Ensure that the TMFAB display conforms to the latest MUTCD requirements for a Type C Arrow Board, contains at least 15 yellow-color lighted elements, and provides sufficient light output such that the TMFAB display is legible at a minimum distance of one mile. Provide a TMFAB panel that is finished with materials that are non-reflective black in color. Ensure that t he TMFAB can display a flashing arrow to the left, a flashing arrow to the right, a flashing arrow pointing to both the left and right simultaneously, a flashing “four corners” caution mode, and other displays if called for on the Plans. Ensure that the TMFAB is programmed to provide automatic dimming of the lighted elements during nighttime operation to eliminate glare to road users. Ensure that t he TMFAB is powered according to the manufacturer’s requirements, typically via the shadow/advance warning vehicle’s power system or via a dedicated battery system. Equip the TMFAB with a back -up battery system to provide continuous operation when failure of the primary power source occurs. Truck- or Trailer-Mounted Changeable Message Sign (TMCMS). Provide a TMCMS that is a 4-ft high by 8-ft wide electronically illuminated changeable sign panel installed at the rear of the vehicle, with the bottom of the panel mounted a minimum of 7 ft above the roadway when in operating mode. Ensure that the TMCMS display: • Conforms to the latest MUTCD requirements for a portable changeable message sign • Consists of either a lamp matrix or full-matrix LED array capable of displaying a variety of user-programmed messages • Provides sufficient light output such that the TMCMS display is visible at a minimum distance of ½ mile and legible at a minimum distance of 850 ft • Automatically adjusts to maintain message legibility and to eliminate glare to road users during nighttime operation Ensure that the TMCMS can display three lines of text with eight characters per line, and each of the flashing arrow and flashing caution modes illustrated in the latest MUTCD for a Type C Arrow
Part 900 — Incidental Construction and Services August 2025
SECTION 928 — SHADOW OR ADVANCE WARNING VEHICLE WITH CRASH CUSHION AND FLASHING ARROW BOARD OR CHANGEABLE MESSAGE SIGN 900-73 Board. Ensure that each text character displayed by the TMCMS is a minimum of 12 in. high and that multiple lines of text are equally spaced vertically. Provide a TMCMS that is controlled by a solid-state unit housed in a weatherproof enclosure that is lighted for night operation. Provide a keyboard entry system to allow the operator to generate unique messages on the TMCMS. Ensure that t he control unit includes a display screen upon which the operator can review messages before they are displayed on the TMCMS. Ensure that the display screen allow s the operator to see the message that is actively displayed on the TMCMS, and allows the operator to save a minimum of five user -programmed messages in the control unit. Ensure that the system saves the messages in internal memory even when power is turned off or unavailable. Power t he TMCMS according to the manufacturer ’s requirements, typically via the shadow/advance warning vehicle’s power system or via a dedicated battery system. Equip t he TMCMS with a back-up battery system to provide continuous operation when failure of the primary power source occurs.
928.03 Construction Methods.
General. Ensure that the shadow/advance warning vehicle with TMA and TMFAB or TMCMS is available for use throughout the duration of the Project. Comply with Section 24-8-4.2 of the Rhode Island General Laws. Maintain the shadow/advance warning vehicle with TMA and TMFAB or TMCMS throughout the Contract period according to the recommendations of the equipment manufacturers. Immediately remove malfunctioning, damaged, or failed equipment from the Project site. No payment will be made for the duration in which the Contractor attempts to use damaged, malfunctioning, or failed equipment on site. Shadow or Advance Warning Vehicle. Turn on the high-intensity, rotating, flashing, oscillating, or strobe lights on the shadow/advance warning vehicle. Ensure that the lights remain operational at all times when the vehicle is actively engaged in controlling or warning road users in a work zone. Position each shadow vehicle to account for roll-ahead distance in the event of an impact, based on the TMA and/or shadow vehicle manufacturer ’s recommendations. This distance should ensure that the shadow vehicle will not roll into the work space or hazard when hit by an errant vehicle. If roll-ahead distance recommendations are not available from the TMA and/or shadow vehicle manufacturer, the example guidelines included in the AAS HTO Roadside Design Guide may be used. When a shadow vehicle is positioned to protect exposed workers and/or to shield a temporary hazard in the roadway, unless otherwise recommended by the TMA or shadow vehicle manufacturer, set the vehicle’s parking brake and place the transmission in neutral gear.
Part 900 — Incidental Construction and Services August 2025
900-74 SECTION 928 — SHADOW OR ADVANCE WARNING VEHICLE WITH CRASH CUSHION AND FLASHING ARROW BOARD OR CHANGEABLE MESSAGE SIGN Truck- or Trailer-Mounted Flashing Arrow Board (TMFAB). Ensure that the minimum on- time of the TMFAB lighting elements is 50 percent during flashing mode operation and that the flashing rate is not less than 25 or more than 40 flashes per minute. Truck- or Trailer-Mounted Changeable Message Sign (TMCMS). The Engineer must approve in advance any TMCMS display messages differing from those called for in the Contract. Do not use any display message requiring more than two phases at any time. Display each phase of the message for at least three seconds, and adjust the display rate per phase so that the entire message can be read at least twice by passing motorists traveling at the posted or statutory speed limit. Do not allow text messages to scroll or travel horizontally or vertically across the face of the TMCMS.
928.04 Method of Measurement.
Shadow or Advance Warning Vehicle with Crash Cushion and Flashing Arrow Board and Shadow or Advance Warning Vehicle with Crash Cushion and Changeable Message Sign will be measured by the number of hours each assembly is deployed in the work in accordance with the Contract TCP or as directed by the Engineer.
928.05 Basis of Payment.
The Department will pay for the completed and accepted quantities as follows: Pay Item Pay Unit Shadow or Advance Warning Vehicle with Crash Cushion and Flashing Arrow Board HR Shadow or Advance Warning Vehicle with Crash Cushion and Changeable Message Sign HR The prices constitute full compensation for all labor, materials, equipment, and incidentals required to finish the work, complete and accepted. Payment for temporary work is included under SECTION 937.
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