Imperative Components of Highway Safety Systems

Modern controlled-access roadways, generally known as “interstates” in the US, facilitate the rapid movement of vehicular traffic across great spaces.  They play vital roles both in promoting commerce and increasing mobility for the general public.  Their specialized nature, however, requires that they employ particular highway safety systems to prevent accidents and promote the smooth transit of cars and trucks.  Some of the crucial components of highways are divided lanes, grade separators, and impact barriers.

Divided Lanes

Known as “dual carriageways” in the UK and as “divided highways” in the US, these roads have parallel lanes for traffic moving in opposite directions.  They have a small strip of land in between, known in the United States as a “median.”  They permit drivers to operate their vehicles at higher speeds than would otherwise be safe, by eliminating the need to be aware of traffic coming from the opposing direction.

The number of lanes on each side of the median is determined by density of travel.  In the United States, the minimum number is two on each side, though this increases to three or even more around large urban areas.  Crossing over the median to change directions is normally prohibited.  Drivers rely on exit and entrance ramps instead.

Increases in the number of cross-median accidents in the past several years has led to efforts to supplement medians with crossing obstacles, including median barriers, guard rails, raised earthworks, and trees or large shrubs.  Efforts to beautify medians are common as well.  In the warm months, wildflowers and blooming shrubs make the divider more visually appealing to travelers.

Grade Separators   

A perennial problem in highway construction is that of traffic flowing in opposing directions.  This is especially common around large population centers, where large numbers of vehicles may need to enter or exit the highway throughout the day.  Grade separators solve this problem with the use of bridges, underpasses, and interchanges.  Multiple roadways are divided from each other vertically, with vehicles moving above and beneath each other.  This allows high speed limits to stay in place even in congested areas.

However, grade separators have been criticized for being costly, complex, and dangerously compact.  These highway safety systems are disliked by nearby property owners, who see them as noisy eyesores and blights on their community.

Traffic Barriers

Known as “guard rails” or “crash barriers,” these structures are intended to prevent vehicles from leaving the roadway and colliding with elements such as trees, buildings, walls, or storm drains.  They also keep motorists from drifting off the paved surface and into adjoining fields, bodies of water, vertical drops, and construction sites.  To ensure they can do their job, prototypes are extensively tested in real-world crash simulations.

Traffic barriers fall into four general classes:

1. Roadside barriers are used as a buffer between straying vehicles and hazards such as those mentioned above.  They’re commonly installed along curves, beside cliff faces, and along railroad tracks.
2. Median barriers reinforce medians by preventing vehicles from crossing over into opposing traffic lanes.
3. Bridge barriers prevent vehicles from leaving bridges and crashing into whatever is beneath them, such as rivers, other roads, railway lines, etc.  They’re usually made from tubular steel and are built higher than roadside barriers.
4. Work zone barriers direct traffic away from highway work crews and equipment.  They’re normally light, portable, and highly visible structures, intended more to inform drivers than to create physical barriers.

Additional Components of Highway Safety Systems

The following structures and devices are used periodically to promote highway safety:

• Traffic calming measures
• Raised curbs
• Warning lights
• Hazard markers
• Local radio broadcasts that warn motorists of nearby safety threats and/or adverse weather conditions.

As the world becomes increasingly urbanized, highway safety systems will play an ever more important role in safeguarding motorists.  Their proper design and construction are high priorities for infrastructure planners and public officials in all developed nations.