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Since 1946

The answers to some of the common questions we are asked can be found below. Be sure to browse the rest of our site to further increase your knowledge and see why Elderlee, Inc. is best equipped to handle your installation needs. If you are unable to find what you are looking for, please do not hesitate to call or use our contact form.

(Note: The answers found here are based on the guidance and interpretation of the Federal Highway Administration or State Specifications. Standards are subject to change without notice.)


Q:  How do I get a quote for guardrail installation?
A:  If you are a general contractor and would like pricing for a government bid or commercial project, please contact our nearest office and speak with our estimating department, or send plans and instructions to information@Elderlee.com.  If you would like a quote for any other type of guardrail installation, please contact our nearest office, or submit your project description via our contact form.  Please be aware that we may request pictures of the site or require an onsite visit by a construction manager.

Q:  What is the difference between the term guardrail and guiderail?
A:  These terms are synonymous.  The Federal Highway Administration states that a few States are required by judicial interpretation to refer to steel beam barriers as “guiderail” because the barriers are not seen as devices that can guard motorists from all instances.  Rather, the steel beam system can only “guide” the car and its occupants.

(In Europe, “guard fence” and “road restraint systems” are the common names for roadside barriers.)

Q:  What is the difference between galvanized, weathering steel (corten), and poly-coated guardrail?
A:  Galvanized steel guardrail is the common silver colored guardrail seen along many of the nation’s roadways.  This type of guardrail has been “galvanized’ by a process that alloys molten zinc to the steel, forming an impenetrable barrier to water and oxygen.  This zinc coating protects the steel from rust and corrosion, giving it an extended lifespan when exposed to the elements.  Galvanized guard rail is bright and shiny when first installed, but dulls in color when exposed to the elements over time.

Weathering steel guardrail is the brown “rust” colored guardrail often seen in parks or places that require an aesthetically pleasing guardrail option.  The Federal Highway Administration states that the use of weathering steel guardrail should be limited, due to possible deterioration concerns. (FHWA Guidance)

Poly-coated or powder coated guardrail is rail that is essentially painted via a powder coating process.  This process is extremely versatile, and can coat guardrail in almost all colors to be aesthetically pleasing or blend in with the surrounding.  Colors can be matched to maintain brand image or highlight potential hazards.  It is generally a more expensive option and requires additional handling and maintenance. Click here to learn more.

Q: Is it OK to use weathering steel (corten) guardrail in longitudinal barriers?
A:  No.  The FHWA states that the use of weathering steel guardrail should be limited.  Where aesthetic concerns are primary, weathering steel guardrail may be used if the owner adopts frequent periodic inspection and replacement schedule (FHWA Guidance).

Roadside barriers and bridges rails are usually close enough to the traveled way that they can be sprayed with water from passing traffic.  In most parts of the country this water contains deicing chemicals during winter months.  In seaside locations in warmer climates the salt laden air deposits corrosive chemicals on barriers.  In northern climates plows can throw snow onto the rail and the abrasive action of the snow can erode the protective layer.  When exposed to these environments, weathering steel never develops the ‘patina’ that slows corrosion as in other less aggressive environments.  Within a few years significant section loss may result.  The interior of box beam barriers and the lap splice of w-beam guardrail can corrode rapidly to the point where the barrier may become more hazardous than the feature it was meant to shield.

Q:  What is the typical post spacing for guardrail?
A:  For a semi-rigid system, guardrail posts are typically installed on 6’3” centers in relation to the typical hole punching on 12’ 6” or 25’ guardrail panels.  Other deflection requirements may call for guardrail posts to be spaced closer together (near trees, electric poles, bridge approaches, etc.).

Q:  What is the typical height of guardrail?
A:  Specifications for the height of guardrail vary by state, but generally it is installed at a height of 27-3/4” with a +3/-1 inch tolerance.  Additional guidance is forthcoming from FHWA to raise the height of guardrail to accommodate new vehicle designs.

Q:  Why does guardrail have blockouts?
A:  The purpose of guardrail blockouts is to reduce the possibility of “wheel snag” on a guardrail post when a vehicle interacts with the guardrail.  These are typically made of wood or recyclable plastic.

Q:  What type of reflectors will be used on the guardrail?
A:  Typically guardrail reflectors or delineators are installed either on the top of the guardrail post (rail riders) or on the rail itself between the splice bolt.  Yellow reflectors are used to delineate guardrail installed in the center of the roadway or median, while silver reflectors are used for guardrail installed along the roadside.  Red and silver striping is also commonly used to delineate guardrail.

Q:  What are structure mounted guardrail posts used for?
A:  A variety of conditions exist that require the used of structure mounted guardrail posts.  Some examples include guard rail mounted to concrete walls or bridge spans, concrete pavement, or surfaces that driven posts are not practically feasible – parking garages are a frequent example.

Q:  What end treatment will be used for the guardrail?
A: Federal and State specifications dictate the use of various guardrail end treatments available in the marketplace today.  Site specific conditions such as the speed limit, slope, or roadside hazards are taken into consideration when selecting an end treatment.  The project owner’s design engineer is responsible for this selection.  For typical installations in a parking lot or driveway, a terminal end section (boxing glove) will be used to cover the ends. 

Q:  What is an impact attenuator?
A:  An impact attenuator or “crash cushion,” is a common device used on our highway system to shield hazardous objects.  Attenuators may be installed on the ends of guardrail, at gore areas, toll booths, concrete barrier ends, bridge piers, or other potentially hazardous areas.

Q:  Why do some States use wood posts, while others use steel posts?
A:  Site specific conditions may warrant the use of wood posts instead of steel posts, such as soil consistency, aesthetic preferences, material availability or even cost.

Q:  Do you sell used guardrail?
A:  We frequently sell used guardrail for private sector uses, such as in parking lots or to cattle farmers for fencing.  Salvaged posts and panel can be a relatively inexpensive way to achieve the desired barrier you’re looking for.  The availability and condition of this type of material varies throughout the year, but please contact one of our representatives via phone if your project is suitable for used material.

Q:  What is the difference between a strong post and weak post system?
A:  Strong post guardrail systems use a W6x8.5x6’ (or W6x9x6’, W6x9x8’) post on 6’3” centers (depending on deflection), while a weak post guardrail system uses a S3x5.7 post on 12’ 6” centers with no blockout.

If you did not find the answer you are looking for, our guardrail products page may be able to help you.