Guard rail or
guardrail, sometimes referred to as
guide railA Guide Rail is a system designed to guide vehicles back to the roadway and away from potentially hazardous situations. There is a legal distinction between a Guide rail and a Guard rail.- Guide Rail Types :...
or
railing, is a system designed to keep people or vehicles from (in most cases unintentionally) straying into dangerous or off-limits areas. A
handrailA handrail is a rail that is designed to be grasped by the hand so as to provide stability or support. Handrails are commonly used while ascending or descending stairways and escalators in order to prevent injurious falls. Other applications include bathroom handrails—which help to prevent falls on...
is less restrictive than a guard rail and provides both support and the protective limitation of a boundary.
Public safety
Most
public spaceA public space is a social space such as a town square that is open and accessible to all, regardless of gender, race, ethnicity, age or socio-economic level. One of the earliest examples of public spaces are commons. For example, no fees or paid tickets are required for entry, nor are the entrants...
s are fitted with guard rails as a means of protection against accidental falls. Any abrupt change in elevation where the higher portion is accessible makes a fall possible. Due to this responsibility and liability, rails are placed to protect people using the premises. Guardrails are generally required by code where there is a drop of 30" or more.
Examples of this are both
architecturalArchitecture is both the process and product of planning, designing and construction. Architectural works, in the material form of buildings, are often perceived as cultural and political symbols and as works of art...
and
environmentalThe natural environment encompasses all living and non-living things occurring naturally on Earth or some region thereof. It is an environment that encompasses the interaction of all living species....
. Environmental guard rails are placed along hiking trails where adjacent terrain is steep. Railings may also be located at scenic overlooks.
Guard rails in
buildingIn architecture, construction, engineering, real estate development and technology the word building may refer to one of the following:...
s are numerous, and are required by building codes in many circumstances. Guard rails along
stairwayStairway, staircase, stairwell, flight of stairs, or simply stairs are names for a construction designed to bridge a large vertical distance by dividing it into smaller vertical distances, called steps...
s are common, and catwalks and
balconiesBalcony , a platform projecting from the wall of a building, supported by columns or console brackets, and enclosed with a balustrade.-Types:The traditional Maltese balcony is a wooden closed balcony projecting from a...
are also lined with them.
Building codes also require that no opening in a guard be of a size such that a 4" sphere may pass. There are three exceptions according to the 2003
International Building CodeThe International Building Code is a model building code developed by the International Code Council . It has been adopted throughout most of the United States.-History:...
Section 1012.3 which allow openings to not exceed 8" or 21" depending on occupancy groups or special areas.
An architect who was famous for creative use of handrails for social stability was
Alvar AaltoHugo Alvar Henrik Aalto was a Finnish architect and designer. His work includes architecture, furniture, textiles and glassware...
. The guard rails of an
observation towerAn observation tower is a structure used to view events from a long distance and to create a full 360 degree range of vision. They are usually at least tall and made from stone, iron, and wood. Many modern towers are also used as TV towers, restaurants, or churches...
such as the
Space NeedleThe Space Needle is a tower in Seattle, Washington and is a major landmark of the Pacific Northwest region of the United States and a symbol of Seattle. Located at the Seattle Center, it was built for the 1962 World's Fair, during which time nearly 20,000 people a day used the elevators, with over...
or
Eiffel TowerThe Eiffel Tower is a puddle iron lattice tower located on the Champ de Mars in Paris. Built in 1889, it has become both a global icon of France and one of the most recognizable structures in the world...
become exaggerated to the point of becoming a
fenceA fence is a freestanding structure designed to restrict or prevent movement across a boundary. It is generally distinguished from a wall by the lightness of its construction: a wall is usually restricted to such barriers made from solid brick or concrete, blocking vision as well as passage .Fences...
or
cageA cage is an enclosure made of mesh, bars or wires, used to confine, contain or protect something or someone. A cage can serve many purposes, including keeping an animal in captivity, capturing, and being used for display of an animal at a zoo.-History:...
. This is also done on
bridgeA bridge is a structure built to span physical obstacles such as a body of water, valley, or road, for the purpose of providing passage over the obstacle...
s and
overpassAn overpass is a bridge, road, railway or similar structure that crosses over another road or railway...
es to prevent
accidentAn accident or mishap is an unforeseen and unplanned event or circumstance, often with lack of intention or necessity. It implies a generally negative outcome which may have been avoided or prevented had circumstances leading up to the accident been recognized, and acted upon, prior to its...
s and
suicideSuicide is the act of intentionally causing one's own death. Suicide is often committed out of despair or attributed to some underlying mental disorder, such as depression, bipolar disorder, schizophrenia, alcoholism, or drug abuse...
s.
Facility safety guardrail
Guardrails are used in a facility setting to protect a company's greatest assets which include their people and expensive equipment.
The strongest guardrail option is utilizing a manufacturer who produces industrial strength guardrail. This guardrail is constructed out of 4" Schedule 80 6" Schedule 40. It is then sleeved in Hi-Density Thermoplastic Polyethylene which makes it maintenance free. It can be mounted using a base-plate or cored into cement to enhance the strength.
Guardrail can also be constructed of 10 gauge high-tensile
steelSteel is an alloy that consists mostly of iron and has a carbon content between 0.2% and 2.1% by weight, depending on the grade. Carbon is the most common alloying material for iron, but various other alloying elements are used, such as manganese, chromium, vanadium, and tungsten...
formed into a two-rib corrugated design with two secondary ribs. This guardrail looks a lot like what you would see in an outdoor setting but is often used in facilities. The issue with this type of guardrail is that once it is impacted, it will need to be repaired and replaced.
A standard guardrail system is mounted to the floor by base plates, which are fastened with anchor bolts. Each guardrail system also includes posts that are commonly fabricated from steel. These posts are often pre-drilled by the manufacturer and include the hardware for installation. Standard galvanized steel systems (specifically 12-gauge) provide durability and are often fabricated in curved, 90 degree variations, for traffic areas. Other variations include cylindrical steel rails and flatter rails, featuring ribbing. For indoor and outdoor areas, railings are typically painted OSHA yellow. The type and quantity of intermediate rails varies according to the application requirements. For instance, a railing can consist of one to three rails and the rails may be coated with UV resistant polyurethane sleeves.
Automotive safety
In traffic engineering, guardrails prevent vehicles from veering off the
roadA road is a thoroughfare, route, or way on land between two places, which typically has been paved or otherwise improved to allow travel by some conveyance, including a horse, cart, or motor vehicle. Roads consist of one, or sometimes two, roadways each with one or more lanes and also any...
way into oncoming traffic, crashing against solid objects or falling into a ravine. A secondary objective is keeping the vehicle upright while deflected along the guardrail. The problem with this is that a guardrail of the optimum height for a car might not keep a truck from toppling over it, while a motorbike might slip under a higher rail.
In most cases guardrails would not be able to withstand the impact of a vehicle just by the strength of the individual posts in the area hit by the vehicle. Instead, the guardrail is effectively one strong band that transfers the force of the vehicle to multiple posts beyond the impact area or into a ground anchor at the end of the guardrail. Newer concrete barriers, while usually strong enough to withstand direct hits by cars, still work on a similar principle in deflecting heavier vehicles such as trucks.
Though they have usually prevented far more serious accidents, guardrails have frequently ranked as among the highest sources of injury and fatality in a fixed-object
crashA traffic collision, also known as a traffic accident, motor vehicle collision, motor vehicle accident, car accident, automobile accident, Road Traffic Collision or car crash, occurs when a vehicle collides with another vehicle, pedestrian, animal, road debris, or other stationary obstruction,...
. Among the primary reasons for this is the type of treatment used at the end of the guardrail facing oncoming traffic. Most end designs will either deflect, absorb, or launch the vehicle.
Deflection causes the vehicle to be redirected back into traffic – particularly dangerous on undivided roadways, as the vehicle may travel into oncoming traffic. Deflection is prevented in modern installations by allowing the guiderail to deform under the load of the crash, giving a 1.5 metre capture zone behind the guiderail. It is important that the grades and fixed objects behind guiderails protect this clear zone, allowing safe capture of the vehicle by the guiderail. If the guiderail is too rigid to deform, deflection may be an issue.
Absorption is when the force of impact is directly transferred between the vehicle and guardrail, which may cause the end to puncture the vehicle. This is most common where a "whale tail" or blunt end treatment exists. To mitigate this a number of guiderail end treatments exist such as "Extruder end treatments", "eccentric loaders" and "Driveway wrap treatments" which result in blunt ends rarely being left exposed in modern installations.
Lastly, a vehicle can become airborne upon striking a guardrail with a buried end treatment, which may negate the purpose of the guardrail, if the vehicle continues beyond the guardrail and strikes the object the guardrail was protecting. Additionally, an airborne vehicle is likely to collide in a manner that the vehicle was not designed for, increasing the risk of failure in the vehicle's collision safety systems. Collapsible guard rails are safer than rigid ones, since a longer collision duration will result in a smaller average impact force.
Transportation engineersTransportation engineering is the application of technology and scientific principles to the planning, functional design, operation and management of facilities for any mode of transportation in order to provide for the safe, rapid, comfortable, convenient, economical, and environmentally...
limit the guardrails as much as possible, as guardrails should only be placed when the roadside conditions pose a greater threat than the guardrail itself. In fact, in the hierarchy of five roadside safety treatments, shielding with guardrails ranks fourth. Therefore, while guardrails are often added as a retrofit to existing roads, newer roads are designed to minimize roadside threats, whether that may include aligning a road on a smoother curve or filling in a ravine which would eliminate the need for guardrail altogether. In addition to new research into end treatments, public awareness among both drivers and engineers has been gradually reducing injuries and fatalities due to guardrails.
There are four general types of guardrail, ranging from weakest
and inexpensive to strongest
and expensive; cable and wood posts, steel and wood/metal posts, steel box-beam, and concrete barriers. While cheaper guardrail is the weakest, often being destroyed from the impact of a light vehicle, it is inexpensive and quick to repair, so this is frequently used in low-traffic rural areas. On the other hand, concrete barriers can usually withstand direct hits from vehicles as heavy as trucks, making them well suited to high volume routes such as freeways. While rarely damaged, they would be considerably more expensive and time-consuming to repair.
Concrete barriersA Jersey barrier or Jersey wall is a modular concrete barrier employed to separate lanes of traffic. It is designed to both minimize vehicle damage in cases of incidental contact while still preventing crossover in the case of head-on accidents....
are frequently installed in the median, being expected to withstand frequent impacts from both sides, while the shoulders of the road often have cheaper guardrail.
Guardrails are sometimes placed beneath the sides of high-sided heavy vehicles (such as lorries, semi-trucks, etc.). to prevent smaller vehicles from passing underneath the heavier vehicle during a collision and being crushed.
Street railings as hindrances and dangers
In places such as
LondonLondon is the capital city of :England and the :United Kingdom, the largest metropolitan area in the United Kingdom, and the largest urban zone in the European Union by most measures. Located on the River Thames, London has been a major settlement for two millennia, its history going back to its...
where pedestrian railings bedeck many corners and streets many cyclist deaths have occurred when motor vehicles pass too close to kerb-hugging cyclists and crush them against the railings. In addition railings have been found to increase the chances of injury to pedestrians for a number of reasons including increasing the inattention of both drivers and pedestrians. For these reasons some localities in the UK have removed pedestrian railings. This was after London's
Royal Borough of Kensington and ChelseaThe Royal Borough of Kensington and Chelsea is a central London borough of Royal borough status. After the City of Westminster, it is the wealthiest borough in England....
did so and found that the rate of injury to pedestrians had decreased three times faster than elsewhere in London.
The removal of pedestrian railings on streets is an example of the
shared spaceShared space is an urban design concept aimed at integrated use of public spaces. It encourages traffic engineers, urban planners and experts from other fields to consult with users of public space when planning and designing streets and squares in both built and non-built environments...
concept in
urban designUrban design concerns the arrangement, appearance and functionality of towns and cities, and in particular the shaping and uses of urban public space. It has traditionally been regarded as a disciplinary subset of urban planning, landscape architecture, or architecture and in more recent times has...
.
See also
- Baluster
A baluster is a moulded shaft, square or of lathe-turned form, one of various forms of spindle in woodwork, made of stone or wood and sometimes of metal, standing on a unifying footing, and supporting the coping of a parapet or the handrail of a staircase. Multiplied in this way, they form a...
- Concrete step barrier
A concrete step barrier is a safety barrier used on the central reservation of motorways and dual carriageways as an alternative to the standard steel crash barrier.The barrier has contained all vehicles up to 13.5 tonnes.-United Kingdom:...
- Traffic barrier
Traffic barriers keep vehicles within their roadway and prevent vehicles from colliding with dangerous obstacles. Traffic barriers installed at the road side also prevent errant vehicles from traversing steep slopes. Traffic barriers installed at the medians of divided highways are also referred...
- Handrail
A handrail is a rail that is designed to be grasped by the hand so as to provide stability or support. Handrails are commonly used while ascending or descending stairways and escalators in order to prevent injurious falls. Other applications include bathroom handrails—which help to prevent falls on...
- Jersey barrier
A Jersey barrier or Jersey wall is a modular concrete barrier employed to separate lanes of traffic. It is designed to both minimize vehicle damage in cases of incidental contact while still preventing crossover in the case of head-on accidents....
External links
- Roadside Hardware Policy and Guidance - United States Federal Highway Administration
The Federal Highway Administration is a division of the United States Department of Transportation that specializes in highway transportation. The agency's major activities are grouped into two "programs," the Federal-aid Highway Program and the Federal Lands Highway Program...