467 SECTION 885
885.01 Requirements
A.Construction. Use detectable warning panels with a minimum size of 1 foot × 1 foot. Use panels with a surface consisting of truncated domes aligned in a square or radial grid pattern. Do not use surface applied detectable warning panels.
B.Dom e Size. Provide truncated domes in a detectable warning surfac e that have a base diameter of 0.9 inches minimum to 1.4 inches maximum, a top diameter of 50 percent of the base diameter minimum to 65 percent of the base diameter maximum, and a height of 0.2 inch.
C.Dome Spacing. Provide truncated domes in a detectable warning surface that have a center -to-center spacing of 1.6 inches minimum and 2.4 inches maximum and a base-to-base spacing of 0.65 inches minimum measured between the most adjacent domes.
D.Friction. Provide panels that have a minimum coefficient of friction of 0.80 when tested according to ASTM C 1028.
E.Materials. Provide Detectable Warning Panels that are cast iron, concrete pavers, stainless steel, or a composite material.
1.Cast Iron. Provide cast iron panels with a minimum thickness of 0.2 inches. Use either grey cast iron that meets AASHTO M 105, Class 35 B or use ductile cast iron that meets ASTM A 536, Grade 65-45-12. Provide panels without a surface coating and allow the panels to transition to the iron’s natural patina.
2.Concrete Pavers. Provide concrete paver panels that meet requirements of ASTM C 936, have a minimum thickness of 3/4 inches, and are yellow or brick red throughout the panel.
3.Stainless Steel. Provide stainless steel p anels that meet the following requirements: - Minimum thickness of 1/2 inches; - Yellow or brick red in color; - Has a baked or powder -type surface applied coating that was applied to the panel during manufacture; and - Show no signs of deterioration or other defects from salt spray after 1,000 hours of exposure according to ASTM B 117. Do not use field-applied surface coatings or paint. 468 4. Composite. Provide composite panels that meet the following requirements: - Minimum thickness of 0.16 inches; - Yellow or brick red throughout the panel; - Minimum compressive strength of 25,000 psi according to ASTM D 695; - Minimum flexural strength of 29,000 psi according to ASTM D 790; - Minimum tensile strength of 11,500 psi according to ASTM D 638; - Maximum water absorption of 0.07 percent according to ASTM D 570; and - Show no signs of deterioration or other defects from salt spray after 200 hours of exposure according to ASTM B 117. Section 894 469 SECTION 894 HIGHWAY SIGNS AND POSTS
894.01 Sign Backing Material
A.Flat Sheet Aluminum. Provide flat sheet aluminum that is an alloy meeting ASTM B 209 Alloy 6061 T6, or 5052-H38.
B.Extruded Aluminum Panels. Provide Extruded Aluminum Panels that meet ASTM B 221 Alloy 6063 T6. Furnish the panels in 12 inch and 6 inch sections. Provide panels that are flat and straight.
C.Shop Surface Preparation and Processing. Prepare sign sheeting and panels to conform with the reflective sheeting manufacturer’s warranty requirements. Shop drill holes. Do not field drill any holes required in the sign backing.
894.02 Retroreflective Sheeting Materials
A.General.
1.Materials. When submitting the certificate of compliance for retroreflective sheeting, submit manufacturer warranties and guarantees for materials, parts, workmanship, or performance. Apply retroreflective sheeting according to manufacturer’s recommendations. Treat the surface of the barricade rails , drums, or cones as recommended by the sheeting manufacturer before applying the reflective sheeting.
2.Silk Screen Printing. Use retroreflective sheeting within one year from the manufactured date. Mark the packaging cartons or roll goods with the manufacturer’s lot numbers and manufacture date.
3.Digital Printing. Fabricate digitally printed signs using equipment, materials and processes that have been certified by the sheeting manufacturer. Submit a copy of the certification to the Engineer with cer tificate of compliance. Follow the sheeting manufacturer’s quality control process during the manufacture process. Apply a UV -protective clear overlay to the entire face of the sign supplied by the reflective sheeting manufacturer.
B.Type III Retroreflective Sheeting Provide Type III retroreflective sheeting that meets ASTM D 4956, Type III.
Source: North Dakota Standard Specifications for Road and Bridge Construction, 2022 Edition. Pages 502–503 of 550.