How It Works: Highway structures

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When you’re on the highway, especially in a rural area, there really doesn’t seem to be much alongside — maybe some trees or a cornfield. But if you look closely, you may notice such things as solar panels, weather stations, and even bird nesting pavilions.

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Depending on where you are in Canada, you may see a roof on stilts, properly known as a kiosk. These are intended as nesting sites for barn swallows, which used to be plentiful but are now listed as threatened, since so many of the barns and other rural structures in which they nested have been removed. They’re sometimes found near new subdivisions built on farmland, but near a highway, it’s usually because the road infrastructure took out their homes.

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How It Works: Highway structures Back to video

Other wildlife is considered when a highway goes in, since the road can create a barrier across existing animal paths. In some cases, crossings are created under bridges or through culverts, both for the animals’ safety and for drivers. Occasionally you’ll find wildlife overpasses: Banff has had one for more than two decades, while Ontario’s sole version is near Burwash, south of Sudbury. These bridges, connecting natural areas on both sides and covered in similar growth, are well-used by animals, especially since tall fencing alongside the roadway directs them to the pass.

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Tall animal fencing is often used alongside highways, but it isn’t always foolproof and you might see a large mound of earth piled up against one side of it. This is an escape ramp, which helps large animals get back if they’ve managed to get onto the roadway side. They go up the mound and land in a sandy patch away from the road, but can’t get back over.

And the highway departments aren’t done with wildlife yet. Depending on the area, you may see bat boxes, to house bats whose homes disappeared when the highway went through; or reptile fencing, either attached at the bottom of a taller wildlife fence or installed on its own, to keep turtles or small mammals from venturing onto the roadway.

The land alongside the roadway may be planted with native wildflower species, both to prevent erosion and to attract butterflies and other pollinators. In areas where snow can be blown off flat fields and drift on the highway, you’ll sometimes find wooden snow fencing erected in winter. Whenever possible, rows of evergreen trees or dense shrubs, preferably native to the area, are planted instead to block the snow from blowing.

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Sometimes you’ll see artificial ponds alongside the highway, especially nestled inside the circle of an on- or off-ramp. In some cases these are to provide for fish when highway construction intrudes on natural waterways, but they may also be built to collect storm water as it drains off the road, and let any sediment settle before the water goes into nearby streams.

Highways must also be monitored, and in addition to traffic cameras, you’ll often see weather stations, easily identified by wind cups spinning away on top. By monitoring the temperature, wind speed and precipitation, crews can plan their maintenance. Prior to a snowfall or the possibility of ice, provinces that use road salt often spread salt brine on the highway .

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This goes on before the bad weather arrives. It dries on the asphalt and prevents ice from sticking, so the plows that come out after the storm arrives have an easier job of scraping the surface. In some jurisdictions, more environmentally-friendly ingredients such as beet juice (left over from processing sugar beets into sweeteners), spent grain mash from beer production, or cheese brine might be used, mixed with less salt than traditional salt-water brine.

If a road requires an electric sign, camera, light or sensor and there’s no power source nearby, you’ll usually see a small solar panel alongside it. You may also see these on the sides of bridges, although you might not see what they’re powering. It may be what’s known as impressed current cathodic protection (ICCP), which uses a small electric current to prevent the reinforced steel in some bridges from corroding. In Ontario, they’ve been in use since the mid-1970s.

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And, of course, there’s the stuff to keep you safe. You’ll often see barrels at bridge abutments, especially if there’s an off-ramp there, usually in a triangle formation. These barrels are intended to absorb crash energy if you run into them, greatly reducing the possibility that you’ll slam into the concrete or metal bridge. Some are filled with sand, while others contain deformable cross-beams that crumple up when they’re hit.

Whether there’s a barrier between the two opposing traffic directions on a highway depends on a few factors, including the width of the median and how many lanes there are. And don’t expect to always see a guardrail on the right: In many cases, crash barriers are only installed when it’s more dangerous to run off the road than it is to hit the barrier. If you see a guardrail all by itself, there’s likely to be something like a sharp drop-off, a bridge, or a sign post on the other side.