Glazing

The glass for window, windshield glazing or windscreen usage must be fully specified as tempered -or- laminated safety glass. Laminated safety glass may be float glass (common) or have a tempered inner layer to reduce spalling.

Tint Levels

Regular, clear, laminated safety glass provides visible light transmittance values of approximately 89%, with solar transmittance of 77%.
Common automotive grade, blue-green tinted, laminated safety glass provides visible light transmittance values of approximately 73% with solar transmittance of 68%.
Common Neutral gray tinted, laminated safety glass provides visible light transmittance values of approximately 44% with solar transmittance of 47%. This level is normally used in the area is with moderate summer climates.
Common Neutral gray tinted, laminated safety glass provides visible light transmittance values of approximately 28% with solar transmittance of 34%. This level is normally used in the area is with warmer/brighter summer climates. It should be noted that this level of tint may also cause some security concerns due to external visibility of the interior of the vehicle.

The solar transmittance values listed with each tint level, are basic reductions associated with the tint levels listed above, reduced solar transmittance may be obtained by using glass coatings or reflective films.

Standard:	ANSI Z 26.1, Safety Code for Safety Glazing Materials for Glazing Motor Vehicles Operating on Land Highways. (Also issued as SAE J674, Safety Glazing Materials-Motor Vehicles and Motor Vehicle Equipment)
Purpose:	ANSI Z 26.1 is typically used to establish the quality and clarity of the glazing, although this standard does contain impact/penetration resistance, rail vehicles typically use the 49 CFR 223 section to specify the impact/penetration resistance for rail vehicles.
Criteria:	Specify standard name, reference table and item number to obtain full criteria
Usage:	ANSI Z 26.1, Table 1, Item 1 for laminated safety glass for usage anywhere in the vehicle including windshields. ANSI Z 26.1, Table 1, Item 2 for laminated or tempered safety glass for usage anywhere in the vehicle except windshields, ANSI Z 26.1, Table 1, Item 3 for laminated or tempered safety glass used in visibility, non-critical applications such as passenger side windows. This level is normally used when specifying heavily

Standard:	Federal Register - 49 CFR, Part 223, Safety Glazing Standards - Locomotives, Passenger Cars And Cabooses
Purpose:	49 CFR, Part 223, is used to specify the impact/penetration resistance for rail vehicles. The test is independent of the glazing material selected (glass or plastic), so this criterion must be used in conjunction with additional wording. There are no glazing quality requirements included with this standard. Note: 49 CFR, Part 223, should be further modified by the specification to require testing within the intended framework to ensure that the window cannot be pushed through the intended rail vehicle opening.
Criteria:	Specify standard name, reference table and item number to obtain full criteria
Usage:	FRA, 49 CFR, Part 223, Type I rating, is used for all forward facing glazing (windshields), usually having a minimum thickness of 14 mm (9/16 in). FRA, 49 CFR, Part 223, Type II rating, is used for all side facing glazing (Typically cab windows), usually having a minimum thickness of 10 mm (3/8 in). This may also be used for passenger side windows, but it should be noted that there is a significant weight increase over the 6mm (1/4 in) glazing.

Standard:	SAE J673 - Automotive Safety Glasses
Purpose:	This SAE Recommended Practice is intended to cover current safety glazing practice applicable to safety glasses for use in motor vehicles and motor vehicle equipment. For transit applications, the glazing edge treatment for multi-layer glazing is important not only for handling but to avoid the glazing from cutting the supporting portion of the window gasket. Laminated glass also requires the edge to be sealed to prevent moisture entering into the PVB layer (causing it to fog or turn white)
Criteria:	Specify standard name, desired edge treatment
Usage:	Edges shall be seamed and ground smooth per SAE J673, Edge no. 4, (and sealed with aluminum tape or equivalent sealer.)

Standard:	ASTM C1036 - Standard Specification for Flat Glass
Purpose:	This specification covers the requirements for annealed, monolithic flat glass of rectangular shape supplied as cut sizes or stock sheets. For transit applications this standard is called for overall quality of the glass and dimensional tolerancing, other glazing quality not discussed in ASTM C1036 is specified to ANSI Z26.1
Criteria:	Specify standard name, quality level, desired tolerances per table 1
Usage:	Glass quality shall conform to ASTM C 1036, Type 1, Class 1, Quality q3. The dimensional tolerance for the cut size dimensions of rectangular shapes, including squareness will be according to ASTM C 1036 Table 1, but not to exceed "0.040in (1.0mm). For other shapes, the cut size shall not exceed "1/16in (1.6mm) of the dimension specified. Unspecified corners shall have a 1/16in (1.6mm) radius.

Standard:	ASTM C1048 - Standard Specification for Heat-Treated Flat Glass - Kind HS, Kind FT Coated and Uncoated Glass
Purpose:	This specification covers the requirements for flat heat-strengthened (Kind HS) and flat fully tempered (Kind FT) coated and uncoated (condition A) glass used in general building construction. Note: heat tempered glass breaks in a spider web pattern, while fully tempered breaks into small cubic pieces - visibility through the glass in significantly diminished.
Criteria:	Specify standard name, kind, condition, type, class, quality level
Usage:	ASTM C1048, Kind FT, Condition A, Type 1 clear, Class 1 clear, Quality Q3 Note: Class 2 is tinted, heat and light reducing, Class 3 is tinted, light reducing.

Standard:	ASTM C1422 - Standard Specification for Chemically Strengthened Flat Glass
Purpose:	This specification covers the requirements for chemically strengthened glass products that originate from flat glass and are used in general building construction, transportation, and other specialty applications. Note: chemically tempered glass typically breaks in the same manner as untempered glass - visibility through the glass is retained. For this reason, it is often used as a second layer in laminated safety glass.
Criteria:	Specify standard name, surface compression level, case depth
Usage:	ASTM C1422, surface compression level 3, case depth level B

Standard:	ASTM E424 - Standard Test Methods for Solar Energy Transmittance and Reflectance (Terrestrial) of Sheet Materials
Purpose:	These test methods cover the measurement of solar energy transmittance and reflectance (terrestrial) of materials in sheet form.
Criteria:	Specify standard name, test method, solar transmittance (percentage transmitted of total solar exposure)
Usage:	ASTM E424, Method A, XX% solar transmittance. (high sunlight areas use 35-40% solar transmittance)

Standard:	ASTM D1003 - Standard Test Method for Haze and Luminous Transmittance of Transparent Plastics
Purpose:	This test method covers the evaluation of specific light-transmitting and wide-angle-light-scattering properties of planar sections of materials such as essentially transparent plastic. A procedure is provided for the measurement of luminous transmittance and haze. Material having a haze value greater than 30% is considered diffusing and should be tested in accordance with Practice E167.
Criteria:	Specify standard name, haze level (%)
Usage:	ASTM D1003, XX% haze. (for typical transit grade plastics about 15-17%)

Note: Polycarbonate glazing is not recommended due to Flammability, Smoke and Toxicity considerations, but if required by the Transit Authority, it may be specified as follows: ANSI Z 26.1, Table 1, Item 4 for rigid plastic, for usage only in specific locations in the vehicle. Penetration resistance may be specified with FRA, 49 CFR, Part 223, Type X rating as desired for the intended application.