Road barrier energy absorbing systems and methods for making and using the same

In an embodiment, a road barrier energy absorption unit can comprise: a vehicle crush section configured to absorb impact energy when impacted with greater than or equal to 5 kN force; a post channel configured to receive a road barrier post; and a guardrail attachment. The energy absorption unit can be disposed over the post and a guardrail can attach to the energy absorption unit. In an embodiment, a road barrier energy absorber system comprises: posts; road barrier energy absorption unit; and a guardrail extending between the energy absorber units. Each post is disposed in one of the energy absorber units. The energy absorber units comprise a vehicle crush section configured to absorb impact energy when impacted with greater than or equal to 5 kN force. In an embodiment, a guardrail can comprise: an outer wall and stiffening elements, wherein the guardrail comprises a plastic.

TECHNICAL FIELD

The present disclosure relates to an energy absorbing system, and especially to a road barrier energy absorbing system.

BACKGROUND

Energy absorber systems are typically used in automotive bumpers for the purpose of absorbing the impact energy generated by a collision. Mainly, the body in white and other components are designed to withstand certain impact load to meet regulation requirements. The energy absorber systems are intended to absorb energy and protect those components from damage. Thus, significant engineering and design effort has focused on designing safer and more durable vehicles.

In contrast, the environment in which the vehicle is operated, e.g., the surrounding infrastructures (such as, road barriers, road dividers, lamppost, parking garage walls and pillars, telephone poles, etc.) are designed as inflexible components that can withstand vehicle impact. Hence, they fail to safeguard the vehicle and the occupants during a collision between the vehicle and the infrastructure. Therefore, even if the vehicle is designed with all the safety technology, the chances of damage to the vehicle and/or occupant(s) still exist in collisions between the vehicle and the infrastructure.

There is a continuing need to enhance occupant safety and vehicle damageability during a collision with the barriers along the periphery of the road.

SUMMARY

Disclosed herein are road barrier energy absorbing systems, and methods for making and using the same.

In an embodiment, a road barrier energy absorption unit can comprise: a vehicle crush section configured to absorb impact energy when impacted with greater than or equal to 5 kN force; a post channel configured to receive a road barrier post; and a guardrail attachment. The energy absorption unit can be disposed over the post and a guardrail can attach to the energy absorption unit.

In an embodiment, a road barrier energy absorber system comprises: posts; road barrier energy absorption unit; and a guardrail extending between the energy absorber units. Each post is disposed in one of the energy absorber units. The energy absorber units comprise a vehicle crush section configured to absorb impact energy when impacted with greater than or equal to 5 kN force.

In an embodiment, a guardrail can comprise an outer wall and stiffening elements, wherein the guardrail comprises a plastic.

The foregoing and other features of the present disclosure will be more readily apparent from the following detailed description and drawings of the illustrative embodiments.

DETAILED DESCRIPTION

Disclosed herein are road barrier energy absorber systems. Compared to steel posts and metal guardrails, these road barrier energy absorber systems can reduce the injury level to the occupants during accidents, reduce damage to the vehicle, give extra reaction time to the driver to control the vehicle, and/or reduce head injury to an individual who impacts the barrier (e.g., a motorcyclist who impacts the barrier after falling).

The road barrier energy absorber system comprises a road barrier energy absorber unit (also referred to as an energy absorber unit), a post, and a guardrail. The post is a separate element onto which the energy absorber unit is disposed (e.g., a metal (e.g., steel), or composite post, which is affix to a horizontal surface and around which the energy absorber unit is located). For example, the post can be stabilized into the ground along a road side. The energy absorber unit can be attached over the post, and guardrail(s) can be attached to the energy absorber unit on the side comprising the vehicle crush section and optionally the head impact section. Optionally, an upper guardrail can be attached across the vehicle crush section and an optional lower guardrail can be attached across the optional head impact section. On the side of the energy absorber unit opposite the guardrail can be a secondary energy absorber for vehicle impact. The secondary energy absorber for vehicle impact can absorb additional energy to prevent the failure of the post. In other words, to prevent the post from bending sufficiently to allow a vehicle to cross the guardrail to the other side of the road barrier energy absorber system (e.g., to pass off the road, and/or into a ditch, and/or off a cliff).

The post can be formed of any material capable of withstanding the desired impact energies without bending to a point wherein the vehicle can pass to the other side of the road barrier energy absorber system. Possible materials include metal such as steel. The post can have various geometries, including polygonal, rounded, and combinations comprising at least one of the foregoing, such as “I” (FIG. 19), “E” (FIG. 20), “S” (FIG. 21), “C” (FIG. 22), and rectangular (FIG. 23). During use, the post is attached to a horizontal surface (e.g., is anchored to the ground or other surface).

The guardrail can be of any shape, thickness, and material that can perform the desired function. For example, that can inhibit a vehicle from passing off the road, across the guardrail, without rupture, at an impact energy of 560 kJ. In other words, the roadside barrier system can meet the European impact requirements of EN 1317.2:1998.

The guardrail can comprise a material having sufficient strength and ductility (e.g., a ductility of greater than 40%, specifically, 40% to 80%, from −40° C. to 120° C., for example, metal (e.g., steel), plastic (e.g., thermoplastic), composite, as well as combinations comprising at least one of the foregoing). Examples of plastics include filled and unfilled materials such as: polycarbonate, polyester, polyolefins (e.g., polypropylene, polyethylene (such as high density polyethylene)), and combinations comprising at least one of the foregoing. Examples of possible guardrail materials include polycarbonate commercially available from SABIC Innovative Plastics under the trademark LEXAN* resins, and polyester-polycarbonate blends commercially available from SABIC Innovative Plastics under the trademark XENOY* resins. The guardrail can also be made with multimaterial system, e.g., with a weatherable material on outer side and the base structure on inner side. For example, the guardrail can be a base structure (e.g., a material having a ductility of greater than or equal to 40% at temperatures from −40° C. to 120° C.), and stiffening elements (e.g., ribs and the like) to form a structure having a modulus of greater than or equal to 3,000 megaPascals (MPa), specifically 3,000 MPa to 50,000 MPa, and more specifically, 10,000 MPa to 50,000 MPa, and with a weatherable coating on an outer surface of the base structure (e.g., a coating comprising an ultraviolet absorber). Optionally the guardrail can comprise non-plastic reinforcement. Possible reinforcement include metal, glass, ceramic, and combinations comprising at least one of the foregoing. The reinforcement can be in various forms such as fibers, particles, flakes, plates, wires, and so forth, as well as combinations comprising at least one of the foregoing.

Guardrail designs include wavy (e.g., “W” shaped) (seeFIGS. 15-18).FIGS. 15-18illustrate various embodiments of plastic (e.g., Xenoy* resin) guardrails. These guardrails can comprise a stiffening element(s) (82,84,86). For example, transverse stiffening element(s) and/or perpendicular stiffening element(s) and/or parallel stiffening element(s)84(seeFIGS. 16 and 17). The transverse stiffening elements can include diagonal stiffening element(s) (e.g., stiffening elements extending from one side to the other side of the guardrail cross-section, at a non-perpendicular angle to the side88of the guardrail, forming triangular sections) (seeFIG. 15). Perpendicular stiffening elements can include stiffening elements that extend from one side88to the other side90of the guardrail cross-section at an angle perpendicular to the outer wall (88,90) of the guardrail. (seeFIGS. 16 and 18) The opening(s)92, between the stiffening elements and the walls can optionally be filled, e.g., with foam or any other suitable material. Optionally, the outer wall can be thicker than the stiffening elements, e.g., to increase the buckling strength of outer walls and improve bending stiffness. For example, outer walls can have a thickness of up to and exceeding 15 mm, specifically, 2 mm to 10 mm, and more specifically, 2 mm to 8 mm, and yet more specifically, 4 mm to 8 mm. The stiffening elements can have a thickness of up to and exceeding 10 mm, specifically, 2 mm to 10 mm, and more specifically, 2 mm to 6 mm. As noted, the stiffening elements can have the same thickness as the outer wall or can have a thickness that is less than the thickness of the outer wall.

The stiffening elements can be located strategically. For example, gaps can be located between stiffening elements to form attachment elements. The attachment elements can be used to attach guardrails together and/or to the roadside energy absorber unit. Some stiffening element designs are illustrated inFIGS. 30-32, which show parallel and perpendicular stiffening elements (FIG. 30), zig-zag stiffening elements (FIG. 31), and multiple zig-zag stiffening elements which form parallelograms (FIG. 32.).

Various methods can be employed to form the guardrail including molding, extrusion, and so forth.FIG. 18illustrates a guardrail formed by an injection molding method. Here, the W section design can be stiffened by stiffening elements on the rear side.

The guardrails can attach to the energy absorption unit with various attachment elements. Possible attachments include mechanical elements such as bolts, rods, and the like. A local steel insert can be used on the energy absorber unit to bolt the guardrail on the energy absorber unit, e.g., to avoid the creep. The metal (e.g., steel) elements can also be designed to absorb the energy, e.g. the steel inserts can be used on the front upper EA or the lower rear EA to absorb the energy.

The energy absorber unit, to which the guardrail attaches, is disposed around the post. The energy absorber unit can be modular or a single unitary component. The energy absorber unit can be produced using various forming techniques, depending upon the desired final design of the unit and the limitations of the forming technique. Some possible forming techniques include molding (e.g., injection molding, compression molding, blow molding, structural foam molding, thermoforming, etc.), extrusion, and combinations comprising at least one of the foregoing processes. For example, a single unitary unit can be formed via blow molding or injection molding. Multiple unit portions (e.g. two as illustrated inFIG. 2A) can be formed, for example, via injection molding.

In structural foam molding, a foaming agent is mixed with the polymer and injected into the cavity. The foaming agent produces a less dense cellular core on the center of the part thickness. This process can be used, for example, to enhance stiffness for the same weight of the material. An inert foaming gas and/or from the gases released from the chemical blowing agent can be used to obtain the cellular core. The parts produced through this process exhibit excellent strength to weight ratio. Sometimes as much as 40% weight reduction is possible using this process.

For example, the energy absorbing units can optionally be covered with aesthetic cover. The energy absorbing units can be designed to crush progressively during impact while maintaining desired force level.

The units can comprise connectors capable of aligning the units and/or of retaining the units together. The connectors can be chemical (e.g., adhesive), and/or mechanical (e.g., complementary protrusions and grooves, snap fit connections, bolts, rivets, etc.). Depending upon the assembly technique, e.g., snap fit or another reversible process, the components of the units can be easily dismantled and reassembled so that portions of units can be replaced without the need to replace the whole unit.

Steel barriers are used typically on the highways. Design consists of a steel post, which can be, for example, an I, C, S, or O cross-section. A separator (e.g., rigid wooden block or C-section) is fixed on the post. Steel W-shape beam (guardrail) is fixed to the separator, which runs along the road length. The steel posts are typically spaced 2 meters (m) apart, although other spacing can be employed if additional energy absorber units are desired.

For roadside barriers, the energy absorber unit can be added on the steel post to improve the energy absorption for vehicle impact and/or human impact. (seeFIG. 1, illustrated schematically inFIG. 3) For example, two energy absorber portions20,30can be designed on front side to safeguard against vehicle impact and to safeguard against human body impact (e.g., a motorcyclist falling off of the motorcycle). Optionally, a second level energy absorber40can be designed on the rear side thereof, e.g., to further support the post and hence further inhibit failure of the guardrail (e.g., further prevent a vehicle from crossing the guardrail). The second level energy absorber can be designed to crush against the horizontal surface4(e.g., the ground) when force is applied to the frontside vehicle energy absorption portion. For example, as is illustrated inFIG. 6, a force “F” contact (and crushes) the frontside absorber, and extra force “F′” (non-absorbed force), pushes the post2in the direction of the original force “F”, causing the post2to bend, and the force “F′” to be absorbed by the second level energy absorber40. (See FIGS.1,2A,2B,6) In such a design, the horizontal surface along with the secondary energy absorber for vehicle impact, both absorbs the impact energy and inhibits the post failure. Post failure can allow the vehicle to proceed across the barrier.

Each road barrier energy absorber unit can be designed for the desired energy absorption. For example, lower energy absorber (30) can be designed to take head impact load to meet the HIC criterion. Upper energy absorber (20) can be designed for the slow speed impact. It can be relatively soft structure to reduce damage to the vehicle. While the energy absorber on the rear (40) will be rigid structure which will get contacted with road and crush.

To attain the desired structural integrity and crush characteristics, each energy absorber portion20,30,40can comprise stiffening element(s). For example, the vehicle crush section20needs a higher crush capability than the head impact section30(e.g., can have greater than or equal to 5, specifically greater than or equal to 10 times, the crush capabilities of the head impact section30). For example, the vehicle crush section can absorb 5 kJ to 40 kJ of impact energy, specifically, 10 kJ to 40 kJ, and more specifically, 20 kJ to 35 kJ of impact energy. For example, the head impact section can absorb 1 kJ to 10 kJ of impact energy, specifically, 2 kJ to 10 kJ, and more specifically, 5 kJ to 10 kJ of impact energy. The second level energy absorber can absorb greater than or equal to 30 kJ, specifically 30 kJ to 200 kJ or more of impact energy, more specifically, 50 kJ to 200 kJ, yet more specifically, 100 kJ to 200 kJ, and still more specifically, 150 kJ to 200 kJ of impact energy.

The head impact section30can be a hollow area formed by an upper crush wall34and a lower crush wall36. These crush walls34,36can extend from the post2to a front wall38extending from crush wall34to crush wall36(e.g., crush walls34,36can extend perpendicular from the post2and/or the front wall38can extend perpendicular to crush walls34,36and/or parallel to post2). Optionally, a space formed between the post and walls34,36,38can be hollow or it can be filled with a compliant material (e.g., a foam, gel, or other material).

Since the vehicle crush section20has greater structural integrity than the head impact section30, it has stiffening element(s) (or more stiffening element(s)), and/or is filled. For example, as with the head impact section30, vehicle crush section20, can comprise protruding walls26extending from the post2, and front wall28extending between the protruding walls26(e.g., protruding walls26can extend perpendicular from the post2and/or the front wall28can extend perpendicular to crush walls26and/or parallel to post2). Located between the protruding walls26and/or between the front wall28and the post2can be stiffening element(s)22,24. Optionally, the stiffening element(s) can comprise a steel insert that can, for example, also absorb energy. The perpendicular and the parallel stiffening elements can be more than one to create stiffening element skeleton. Alternatively, or in addition, the area can be filled with hexagonal stiffening elements (honeycombs). (SeeFIGS. 24-26) Each stiffening element is oriented parallel, perpendicular, or diagonal to the post2in order to attain the desired crush characteristics. For example, the vertical stiffening element(s)24, between the post2and front wall28, can be parallel to the post2. Optionally, the horizontal stiffening element(s)24, between the walls26, can be perpendicular to the post2. If further structural integrity is desired, the stiffening element(s)22can be oriented at an angle (i.e., other than 90 degrees) to the post2such that multiple stiffening elements converge toward the front wall28, forming triangular structure(s) in the vehicle crush section20. Other stiffening element combination can also be designed as shown inFIGS. 24-26.

Between vehicle crush section20and head impact section30can be further energy absorption, or an area of reduced material. For example, concave area18can be located therebetween, e.g., to reduce material consumption in forming the energy absorber unit10, and/or to add aesthetic qualities. As can be seen inFIGS. 1 and 2A, the concave area18can be formed by walls converging both toward the post2and/or toward the opposite side16or17. Optionally, the front most portion of the concave area18can be open (FIGS. 1 and 2B), or can comprise a front wall19(FIG. 2A).

The energy absorber units can be, for example, injection molded. The wall and/or stiffening element thicknesses can be 3.0 to 8.0 millimeters (mm) thick. Outer wall(s) can be thicker compared to the stiffening elements, wherein the stiffening elements in combination with outer walls are designed to absorb the required impact energy. The openings formed between the stiffening elements and walls can optionally be filled with foam and/or any alternative suitable material, e.g., to modify the energy absorption characteristics. Optionally, the stiffening elements(s) can include steel insert(s) which can optionally further absorb energy.

The post2can be located through the energy absorber unit10in a hollow area that is simply open or that is formed to the particular post shape (e.g., configured to an I beam as is illustrated in FIGS.2A,2B). Here, post channels70are formed between vertical stiffening elements76(which can optionally extend along the post2, forming one side of the head impact section30and/or the vehicle crush section20).

On the rear side of the post2can be the secondary energy absorber40. Since the secondary energy absorber40has a much higher crush capability than the vehicle crush section20(e.g., can have greater than or equal to 5, specifically, greater than or equal to 10 times the crush capabilities of the vehicle impact section20) it can have additional stiffening element(s) and/or filler. As is illustrated, the secondary energy absorber40can have a series of horizontal transfer stiffening element(s)52which can extend from a vertical post stiffening element76to a transverse wall48and/or to a horizontal foot wall50. Horizontal foot wall50can be substantially parallel to the post2. Optionally the horizontal foot wall50can have an angle of 10° to 90° from a vertical axis “V”. Optionally, the transverse wall48, can extend away from the vertical stiffening element(s)76to the horizontal stiffening element(s)50. Horizontal stiffening element(s)50, along with angled stiffening element44, form the foot42that enables transfer of crush energy from vehicle, to the post2and to the ground (e.g., horizontal surface2). Optionally, the foot42can comprise support stiffening element(s)46, e.g., disposed between horizontal stiffening element50and angled stiffening element44. For example, a support stiffening element46can extend between the horizontal stiffening element50and angled stiffening element44to divide the space therein in half.

Other stiffening element combination can also be designed as shown inFIGS. 27-29. These figures illustrate interior designs of the secondary energy absorber. As can be seen, various combinations of diagonal (not parallel or perpendicular to the surface to which the assembly is mounted (other than “H” or “V” axes)), horizontal (“H”) (parallel to the surface to which the assembly is mounted), and vertical (“V”) (perpendicular to the ground (surface to which the assembly is mounted)).FIGS. 27 and 28illustrate multiple triangular sections which provide further structural integrity. It is noted that in these figures, other optional stiffening element designs in the foot42are illustrated.FIG. 27illustrates a zig-zag stiffening element46′ that extends from a base of the foot42.FIG. 28illustrates a straight stiffening element46that extends from the base of the foot42to diagonal ribs such that the stiffening element46ends at the peak of a triangle.FIG. 29illustrates honeycomb stiffening elements (e.g., multiple hexagonal cells). When honeycomb stiffening elements are used, the amount of cells is dependent upon the desired energy absorption as well as the molding capabilities of the tooling. Optionally, the side of the cell can be greater than or equal to 10 mm.

These energy absorber units can be placed on each post (e.g., steel post). These energy absorbers are also designed to fit on the existing steel post so replacement of this post is not needed. For example, as is illustrated inFIG. 4, which illustrates a cut-way portion of a roadside barrier system with a complete assembled energy absorption units on the steel posts. Here, polymer energy absorption units are fixed around the steel post and the polymer W beam is affixed to the energy absorption units.

Polymeric or composite materials can be used for manufacturing of the energy absorber and/or guardrail. Some examples of materials include for example, possible thermoplastic materials include polybutylene terephthalate (PBT); acrylonitrile-butadiene-styrene (ABS); polycarbonate (PC) (LEXAN* and LEXAN* EXL resins, commercially available from SABIC Innovative Plastics); polycarbonate/PBT blends; polycarbonate/ABS blends; copolycarbonate-polyesters; acrylic-styrene-acrylonitrile (ASA); acrylonitrile-(ethylene-polypropylene diamine modified)-styrene (AES); phenylene ether resins; blends of polyphenylene ether/polyamide (NORYL GTX* resins, commercially available from SABIC Innovative Plastics); blends of polycarbonate/polyethylene terephthalate (PET)/PBT; polybutylene terephthalate and impact modifier (XENOY* resins, commercially available from SABIC Innovative Plastics); acrylic-styrene-acrylonitrile (ASA, GELOY* resins, commercially available from SABIC Innovative Plastics); polyamides; phenylene sulfide resins; polyvinyl chloride PVC; high impact polystyrene (HIPS); polyethylene; low/high density polyethylene (L/HDPE); polypropylene (PP) (e.g., reinforced polypropylene; glass fiber reinforced polypropylene; long glass fiber reinforced polypropylene); expanded polypropylene (EPP); polyethylene and fiber composites; polypropylene and fiber composites; long fiber reinforced thermoplastics (VERTON* resins, commercially available from SABIC Innovative Plastics) and thermoplastic olefins (TPO), as well as combinations comprising at least one of the foregoing. For example, the material can be PC/PBT, a polyolefin (e.g., polypropylene such as glass filled polypropylene, long glass fiber polypropylene, etc.) as well as combinations comprising at least one of the foregoing. Particularly useful polymers include polybutylene terephthalate and impact modifier (XENOY* resins, commercially available from SABIC Innovative Plastics), polycarbonate (PC) (LEXAN* and LEXAN* EXL resins, commercially available from SABIC Innovative Plastics), and combinations comprising at least one of the foregoing resins.

An exemplary filled resin is STAMAX* resin, which is a long glass fiber filled polypropylene resin also commercially available from SABIC Innovative Plastics. Some possible reinforcing materials that can be used in any of the above described materials include fibers, such as glass, carbon, natural, modified natural, modified glass, modified carbon, polymeric, and so forth, as well as combinations comprising at least one of the foregoing; e.g., long glass fibers and/or long carbon fiber reinforced resins; fillers, such as mineral fillers. The glass fibers and/or carbon fibers can be long or short, or a combination thereof. Combinations comprising at least one of any of the above-described materials can also be used.

Optionally, a radio frequency identification (RFID), or the like, can be embedded in the structure to obtain and/or retain desired information.

During the impact, energy is transferred to the vehicle crush section20and/or the head impact section30. If the energy is beyond the absorption capabilities of the vehicle crush section20, energy transfers to the post2, bending it back, and transferring energy to the secondary energy absorber40. The energy transfer prevents recoil toward the vehicle and/or individual, thereby enabling greater reaction time and a greater opportunity to minimize physical and property damage.

Optionally, energy absorber units have a reflector (e.g., a reflective coating), e.g., to enhance visibility of the unit in low visibility situations (e.g. at night).

The following non-limiting examples are intended to further illustrate the energy absorber systems.

EXAMPLES

Simulations

Road barriers are analyzed for the impact load. The assembly will be impacted with the rigid impactor with total energy of 200 kJ.FIG. 5shows the impact setup. The impactor impacts at an angle of 20°.FIG. 6shows the crushing of the energy absorption units during impact. The upper part of the energy absorption unit crushes during the vehicle impact.FIG. 8graphically illustrates a force deformation comparison of road barrier with and without energy absorption unit. The energy absorption unit can provide higher reaction time during impact, also the reaction force will be lesser compared to the road barrier without an energy absorption unit. The energy absorsion in the first 200 millimeters (mm) intrusion level is by the front upper energy absorber (the vehicle crush section), which is designed to crush and transfer lower reaction force to the vehicle. After the front energy absorber crushes, the load is transfer to the steel post and the rear energy absorber (the secondary energy absorber for vehicle impact) to absorb the energy. In case the impact energy increased to 500 kJ, higher energy will be transferred to the rear energy absorber.FIG. 33shows the crushing of the energy absorption unit during impact.FIG. 34graphically illustrates a force-deformation comparison of the road barrier with energy absorption unit for 200 kJ and 500 kJ energy.

Head impact studies are carrier out where head is impacted at velocity of 40 km/h on a steel pole (seeFIG. 10), a polymer energy absorption unit (seeFIG. 11A), and between adjacent energy absorber units, along a lower polymer guardrail (seeFIG. 12).FIG. 13shows the force deformation curves. Studies indicate that in case of impact directly on the steel pole the force is very high thus the possibility of head injuries will be higher. In case of head impacting the energy absorption unit, the energy absorption unit absorbs the energy during the head impact and will significantly reduce the impact force on the head. (seeFIG. 11B) As can be seen from the graph, the impact on the energy absorber unit (FIG. 11A) maintained a force level of less than or equal to 8 kN, while the pole impact (FIG. 10) exhibited a force exceeding 30 kN. This will reduce the chance of head injury damage.

In an embodiment, a road barrier energy absorption unit can comprise: a vehicle crush section configured to absorb impact energy when impacted with greater than or equal to 5 kN force; a post channel configured to receive a road barrier post; and a guardrail attachment. The energy absorption unit can be disposed over the post and a guardrail can attach to the energy absorption unit.

In an embodiment, a road barrier energy absorber system comprises: posts; road barrier energy absorption unit; and a guardrail extending between the energy absorber units. Each post is disposed in one of the energy absorber units. The energy absorber units comprise a vehicle crush section configured to absorb impact energy when impacted with greater than or equal to 5 kiloNewton (kN) force.

In an embodiment, a guardrail can comprise: an outer wall and stiffening elements, wherein the guardrail comprises a plastic.

In the various embodiments: (i) the unit further comprises a head impact section located below the vehicle crush section, and a second guard rail attachment, wherein the guard rail attachment aligns with the vehicle crush section, and wherein the second guard rail attachment aligns with the head impact section; and/or (ii) the unit a secondary energy absorber located on a side of the post channel opposite the vehicle crush section, and configured to absorb energy transferred from the vehicle crush section to the secondary energy absorber, and wherein, in use, the secondary energy absorber crushes against a horizontal surface to which the unit is attached; and/or (iii) the head impact section is configured to absorb 1 kJ to 10 kJ of energy during impact, wherein the vehicle crush section is configured to absorb 5 kJ to 40 kJ of energy during impact, and wherein the secondary energy absorber is configured to absorb greater than 30 kJ of energy during impact; and/or the secondary energy absorber is configured to absorb greater than 100 kJ to 200 kJ of energy during impact; and/or (iv) the unit further comprises a secondary energy absorber located on a side of the post channel opposite the vehicle crush section, and configured to absorb energy transferred from the vehicle crush section to the secondary energy absorber, and wherein, in use, the secondary energy absorber crushes against a horizontal surface to which the unit is attached; and/or (v) wherein the secondary energy absorber comprises stiffening elements; and/or (vi) wherein the vehicle crush section comprises stiffening elements; and/or (vii) the unit further comprises filled spaces between the stiffening elements; and/or (viii) wherein the road barrier energy absorption unit comprises a weatherable coating having a UV absorber; (ix) wherein the energy absorber units further comprise a head impact section located below the vehicle crush section, and a second guardrail attachment; and wherein the system further comprises a second guardrail extending between the second guardrail attachments and across the head impact section; and/or x) the system further comprises a secondary energy absorber located on a side of the post opposite the vehicle crush section, and configured to absorb energy transferred from the vehicle crush section through the post to the secondary energy absorber, and wherein, in use, the secondary energy absorber crushes against a horizontal surface to which the energy absorber units are attached; and/or (xi) the head impact section is configured to absorb 1 kJ to 10 kJ of energy during impact, wherein the vehicle crush section is configured to absorb 5 kJ to 40 kJ of energy during impact, and wherein the secondary energy absorber is configured to absorb greater than or equal to 30 kJ of energy during impact; and/or (xii) wherein the guardrail is a polymer guardrail; and/or (xiii) wherein the polymer guardrail comprises stiffening elements; and/or (xiv) the guardrail and the road barrier energy absorption unit comprises a weatherable coating having a UV absorber; and/or (xv) the guardrail can further comprise a weatherable coating on the outer wall, wherein the weatherable coating comprises a UV absorber; and/or (xvi) the guardrail is plastic; and/or (xvii) the guardrail comprises non-plastic reinforcement (e.g., within plastic walls); and/or the guardrail has a metal reinforcement; and/or (xviii) the guardrail has a reinforcement selected from a metal plate, metal wires, and combinations comprising at least one of the foregoing.

As used herein, approximating language may be applied to modify any quantitative representation that may vary without resulting in a change in the basic function to which it is related. Accordingly, a value modified by a term or terms, such as “about” and “substantially,” may not to be limited to the precise value specified, in some cases. In at least some instances, the approximating language may correspond to the precision of an instrument for measuring the value.

In general, embodiments may alternately comprise (e.g., include), consist of, or consist essentially of, any appropriate components herein disclosed. The embodiments may additionally, or alternatively, be formulated so as to be devoid, or substantially free, of any components, materials, ingredients, adjuvants or species used in the prior art compositions or that are otherwise not necessary to the achievement of the function and/or objectives of the embodiments.

As used herein, approximating language may be applied to modify any quantitative representation that may vary without resulting in a change in the basic function to which it is related. Accordingly, a value modified by a term or terms, such as “about” and “substantially,” may not to be limited to the precise value specified, in some cases. In at least some instances, the approximating language may correspond to the precision of an instrument for measuring the value. Likewise, the term “operably connected” can refer to circumstances where two members are directly or indirectly joined such that motion can be transmitted from one member to the other member directly or via intermediate members. In another embodiment, the term refers to circumstances where two objects are joined in any desired form for example, mechanically, electronically, directly, magnetically, and the like.