731.01 Description. This item shall consist of furnishing,
installing, relocating, maintaining, repairing, and removing temporary and permanent impact attenuation barrier systems, including pads, nose covers, and transitions. The impact attenuation barrier system shall be of the type shown on the pl ans. The impact attenuation barrier system shall satisfy the Nation al Cooperative Highway Research Program (NCHRP) Report 350 or the Manual for Assessing Safety Hardware (MASH) requirements for a Test Level 3 (TL-3) crash cushion. A copy of the Federal High way Administration’s (FHWA) acceptance letter with all attachments for each impact attenuation barrier system shall be sub mitted to the Engineer. Impact attenuation barrier systems shall be fabricated and installed in accordance with the plans and with the crash testing documentation provided in the FHWA acceptance lette r, which is available at FHWA’s website at: http://safety.fhwa.dot.gov/roadway_dept/policy_guid e/road_hardware/ , if current testing criteria have been fulfilled.
731.02 Materials. The Contractor shall furnish a certification
from the manufacturer or supplier that the impact a ttenuation barrier supplied is non-gating, redirective and meets the r equirements of NCHRP Report 350 or MASH for a TL-3 crash cushion. An impact attenuation barrier system specifically d esigned for protecting motorists from impacting temporary concr ete barrier walls or other fixed objects adjacent to the roadwa y shall be utilized. The impact attenuation barrier system shall be non- gating, redirective and compatible with the site geometry s hown on the plans. Sand Barrels will not be allowed for Tempor ary Impact Attenuation Barriers. Sand barrier installations shall consist of a found ation pad and modules consisting of three basic components: cylin der, lid, and spacer. The Contractor shall have the option of co nstructing either a rigid or flexible foundation pad. The material requirements for the barrier installat ion are as follows:
a.Rigid Pad. A rigid pad shall be constructed of a course of concrete of the thickness shown on the plans. Conc rete shall comply with Section 802 for Class M concrete. The Department will perform all acceptance sampling and testing at the frequencies shown for Contractor acceptance testing in Subsecti on 802.06.
b.Flexible Pad. A flexible pad shall be constructed of Aggregate Base Course, Class 1, and ACHM Surface Co urse, to the dimensions shown on the plans. At the option of th e Contractor, full depth ACHM Surface Course may be used to construct the flexible pad. Materials shall comply with the requirements for the appropriate items of Sections 303 and 407.
c.Cylinder. The cylinders shall be 36" (900 mm) in diameter and may be either 30" or 36" (750 mm or 900 mm) in height. The cylinders shall be molded from a tough, high densit y, polyethylene material that is durable and weatherproof, having a thickness of approximately 1/4" (6 mm). The cylinder shall be o f such design, material, and construction as to shatter upon impac t. Unless otherwise specified, the color of the cylinder shal l be yellow.
d.Lid. The lid shall be formed from high density polyeth ylene and shall be of such diameter as to ensure a tight fit.
e.Spacer. The spacer shall be in the form of a core with a disc and seal supporting the sand mass or an inner conta iner with a stem. The spacer heights shall be designed to ensure that the center of gravity of each module is at the proper elevation t o control the attitude of impacting vehicles.
f.Sand. Sand may be any type of building sand of average grain texture. Wet sand from outside storage or on open trucks, exposed to rain, is acceptable, provided it is not saturated to a liquid or semi-liquid state.
731.03 Construction Requirements. The subgrade area for the
foundation pad shall be shaped and compacted to the required section. Compaction shall be accomplished by any m ethod satisfactory to the Engineer. The foundation pad s hall be constructed as stated above. Each module shall be placed at the location and to the dimensions shown on the plans. The Contractor shall be responsible for outlining with paint the l ocation of the modules for future reference. The Contractor shall mark (with paint) the weight of sand in each module as indicat ed on the specific site plan. The modules shall be placed in front of the hazardous object according to the dimensions shown on the pla ns. To facilitate lid installation there shall be a 3/8" - 5/8" (10 m m - 15 mm) clearance between module tops. After the cylinder is placed in proper location and the proper spacer is assembled and placed in the cylinder, san d shall be placed to the required depth as coded on the module and th e lid securely installed. Impact attenuation barrier system shall be fabricat ed and installed according to the manufacturer’s most current recomm endations and installation methods. Any damage caused by the Con tractor to the materials required for the impact attenuation barri er system shall be repaired or replaced immediately at no cost to the Department. In the event that the impact attenuation barrier sy stem is damaged at no fault of the Contractor, all damaged parts sh all be replaced immediately by the Contractor to restore the Impact Attenuation Barrier to a fully functional condition. Replacing damaged parts will be paid for under the item Temporary Impact At tenuation Barrier (Repair). In the event that a crash cushio n is damaged beyond repair at no fault of the Contractor, it sha ll be immediately replaced and paid for under the item Temporary Impa ct Attenuation Barrier.
731.04 Method of Measurement. Impact Attenuation Barrier
Systems will be measured by the unit of the type sp ecified. Each unit shall include a foundation pad and a specified number of impact modules, when applicable. Temporary Impact Attenua tion Barrier previously furnished and installed, which is author ized to be relocated, will be measured by the unit. Relocatio ns for the convenience of the Contractor will be at no additio nal cost to the Department.
731.05 Basis of Payment. Work completed and accepted and
measured as provided above will be paid for at the contract unit price bid per each for Temporary or permanent Impac t Attenuation Barrier of the type specified, which price shall be full compensation for excavation and/or embankment; for construction of the pad; for furnishing and installing cylinders, complete with filler and lids; and for all materials, labor, equipment, tools, and inc identals necessary to complete the work. Payment will be made under: Pay Item Pay Unit Impact Attenuation Barrier (Type___) Each Temporary Impact Attenuation Barrier Each Temporary Impact Attenuation Barrier (Relocation) Each Temporary Impact Attenuation Barrier (Repair) Each Temporary Impact Attenuation Barrier Left in Place Each
Source: , Edition.