The fire service is very familiar with tempered and laminated glass. However new technology has introduced other
types of windows and glazing material that will have different breaking characteristic and that will influence
removal at a crash scene.
Laminated Glass - This glass consists of a plastic interlayer, made from polyvinylbutyral, sandwiched between two
layers of annealed glass. In general this is used for the windshield.
Recent studies have shown that high injury and fatality rates occur each year in rollover crashes and are directly
attributable to occupant ejection through openings other than the windshield. Standard tempered glass does not offer
protection from ejection. The use of laminated glass could prove beneficial in reducing occupant ejection since it
is designed to maintain integrity upon impact.
Current use of laminated glass in automotive sidelites is emerging in high-end Europen autos including the Mercedes
"S" Class and Audi A8 models. It is expected that laminated sidelites will be offered as standard equipment on
lesser models in the very near future.
Laminated Glass can be cut with several tools such as an Axe, Air Chisel, Glas-Master tool or reciprocating saw.
These techniques will generate small glass fragments and dust. The protection of the victim and rescuer should be
considered before the glass is removed.
Tempered Glass - This type of glass is subjected to a special tempering or hardening and is extremely tough
and break-resistant. It is mostly used in side and rear windows however some older cars used tempered glass
for windshields. Rescuers have frequently used the tempered side and rear windows to make a quick entry into
the vehicle. This is due to the relative ease with which tempered glass can be broken and removed. For
reasons noted under the laminated glass section, it is likely that tempered glass will be replaced in the
future by either laminated glass or by one of the new technologies. Thus the rescuer will have to develop
new techniques to provide quick access to the interior.
Tempered glass can be broken with an axe, spring-loaded center punch or any other type pointed tool. Tempered
glass will shatter into many tiny glass fragments when struck with sufficient force. Typically a blow (from
a center punch or axe) applied to a corner of the pane will shatter the glass. The rescuer and patient should
be protected from possible glass fragments. Often the glass will shatter but remain in place allowing the
rescuer to carefully remove the fragments away from the patient.
Security Glass - As an additional protective barrier for vehicle occupants, BMW has introduced a new "break-resistant
security glass" on the 750iL. The windshield and all of the windows, side and rear, have a unique glass/polycarbonate
layer construction (laminated) that resists the breakage. The door glass is constructed in five layers consisting
of outer glass, thermoplastic polyurethane sheeting, impact-resistant polycarbonate sheet, inner glass and
anti-lacerative film.
Because of the difficulty in breaking of this glass it is suggested to remove this type of glass intact with
the door. Cutting this security glass can be achieved with an axe, or reciprocating saw once a hole has been made.
Plastics/ Polycarbonate Windows - This new product is lighter than glass and much more theft resistant. The design
goal is to replace fixed side and rear glass windows in the automobile. Polycarbonate windows do not react like
conventional tempered safety windows and are break resistant.
Because of the difficulty in breaking of this type of material it is suggested to remove the door with the window
intact. A reciprocating saw with a variable pitch blade of 10-14 teeth per inch cut nicely, once a hole has been made.
