How Are Roads Built on Mountains? The Process Explained

Published Categorized as Infrastructure
Winding Mountain Road

Building a road on or around mountains is no simple task. Roads built on mountainsides take weeks, even months of planning and surveying just to determine where to put them. From there, the task becomes even more dangerous and hands-on, but with the help of some heavy machinery and months of work, roads are paved and finished for commuters.

Roads are built on mountains by carefully surveying the region, then methodically cutting or blasting into the mountain’s side. From there, roads are mapped and paved before being finished and ready for commuters to use.

In this article, we’ll look at the process of roads being built on mountains and all of the careful steps that go into planning a mountain road. Additionally, we’ll answer some commonly asked questions about building roads on mountains.

What is the Process for Building Roads on Mountains?

The process for building roads on mountains involves surveying, drilling, blasting, and the paving of roadways. It’s a time-consuming and often dangerous task and depends heavily on the planning portion of the process.

Roads are generally built from the valley or plain up towards a mountain range, not vice versa. Because of this, roads need to be either:

  • Blasted out of rock cliffs and slopes using explosives or
  • Carved along natural contours in the ground, including ledges and gorges.

This is challenging work as it requires digging deep into the side of any type of hill with no guarantee that something won’t go wrong during construction, such as rocks falling onto workers below. In addition, there’s always a chance for an avalanche if they’re working too close to one end or another – especially when blasting through cliffsides!;

Roads in Mountainous Areas Must First Be Surveyed

Roads are surveyed to determine the best path for them to be built along. This route takes into account many factors such as weather patterns, the slope of mountain faces that need roads on or through them, etc.

It’s also important to remember that roads are built up mountains, not down them. This is because roads cut into the side of a mountain become susceptible to rockfalls and landslides, which can be hazardous for vehicles traveling on roads as well as construction workers building it.

There are nearly ten different types of surveys, but for roads, especially those along mountainsides, engineering surveys are used. Engineering surveys focus on surveys conducted during the planning and execution of engineering projects, such as:

  • Roads
  • Railways
  • Pipelines
  • Drainage systems, and so on.

The engineering survey process works like this:

  • Roads are first surveyed on paper or by hand.
  • It entails taking measurements, performing computations, drafting plans, and determining specific locations.
  • The surveyor may be called upon to measure heights and distances, establish buildings, bridges, and roads, calculate areas and volumes, and draw plans at a certain scale.

Once the best route has been discovered, then roads can be built along it using bulldozers and other heavy construction equipment. This equipment is necessary to clear mountainsides of trees and rocks while workers cut through solid rock with jackhammers for support beams.

Surveying roads is a vital part of the process because it helps engineers decide on what types of roads need to be built and how they should be put into place so everyone can have safe access from point A to point B.

Road surveys are performed using:

  • Laser equipment
  • GPS technology
  • High-precision cameras with video recording capability
  • Aerial photography systems that produce both still images and digital videos for site documentation purposes, etc.

Road Are Designed and Mapped by Engineers After Surveys

Once a survey is completed, design begins with engineers who map out specific locations where roads will go, including cuts and fills.

A road grade is determined during design that helps estimate what kind of cut or fill soil materials will be needed while still meeting requirements set forth by environmental agencies regarding groundwater.

Once the road is leveled out, materials such as asphalt or concrete are brought in to create a smooth surface that vehicles can drive across all year without fear of damage from sleet, snow, rain, etc. Its important roads don’t just look nice, but they must stand up against Mother Nature too!

Drilling and Blasting Contractors Are Used To Cut Mountainsides

After engineers have surveyed and mapped roads, the mountains must be drilled and blasted to create a level surface for the road to be paved. This method requires roads to be cut into the mountainside, which is done by drilling holes deep into the mountain.

These holes are then filled with explosive material and detonated in order to open up space for roads or railways that were not previously possible without affecting groundwater sources.

This process is called “blasting,” and it’s used extensively on roads built on mountainsides and railways. The material that’s blasted off the mountainside needs to be collected, sorted out by size then reused or recycled. Much of this material is used to fill in the valleys and roads built on flatlands.

The blasting creates small particles of crushed rock called “rock dust” when it’s blasted out of a hole drilled in rocks, causing them to disintegrate almost immediately due to air pressure pushing against them. This fine powdery substance must be cleaned up quickly, so it doesn’t affect surrounding areas by bringing down mudslides or contaminating nearby bodies of water.

The best way to clean this debris is by using heavy machinery equipped with vacuums attached right on top, so all the dust gets sucked up and disposed of.

This is a massive job and requires extensive preparation, including:

  • Clearing out trees
  • Removing stumps
  • Relocating rocks that might get in the way of roads

Before any actual blasting takes place, roads are measured to ensure accurate results when they’re ready for use. Roads start with at least two sides, which consist of both an upper and lower surface that meet at 90-degree angles. This part must be done precisely, so there’s no danger of accidents or mishaps later down the road during construction.

How Are Roads Paved and Finished in Mountainous Areas?

The next step is laying down several layers:

  • First comes gravel
  • Then compacted dirt
  • Followed by asphalt.

Each layer serves its own purpose in building strong roads capable of handling heavy traffic loads over long periods without wearing away quickly.

After the location on which the road will be built has been cleaned of all vegetation, trees, bushes, and shrubs, it must be prepared. The surface is then shaped, mounted, and graded after this work is done:

  • Mounting: The shape of the road is determined by the foundation. Excavation equipment and bulldozers are used to move and place dirt and earth over the road during this phase.
  • Grading: After the road has been built, it must be graded. The surface layer is smoothed and leveled using a combination of hand labor and machinery known as graders.
  • Aggregating: After the soil has been leveled, an aggregate foundation of soil, concrete, and limestone is laid to ensure stability. Curbs, gutters, and drains are also installed during this stage.

Mountain roads are built using similar steps but often require certain modifications based on what type of terrain they will be built upon. For instance, roads that are being constructed over mountains need several different types of materials to ensure stability throughout construction, including:

  • Metal braces
  • Bolts
  • Screws, and
  • Specialized equipment like excavators capable of digging up large rocks without breaking them into smaller pieces too small to handle.

These projects can take anywhere from a few weeks to several years, depending on the terrain and what materials need to be used.

Asphalt Waterproofing Is the Final Step in Paving

Asphalt provides weatherproofing and enhances road strength even more by adding another layer that prevents water from seeping through cracks in between layers of gravel or dirt.

Asphalt roads provide excellent traction for cars during dry conditions and periods of wetness. This is because they’re paved with stones or gravel chips (known as aggregate) mixed together with asphalt.

Asphalt is laid in two layers:

  • A very thin layer called a “tack coat” which is spread over the road’s surface and allowed to dry.
  • Then another, thicker layer of asphalt known as the “binder course” is laid over the top.

The binder course assures that roads can withstand normal wear-and-tear from cars, trucks, and other vehicles traveling on them for years without having to be resurfaced.

These roads are built by professionals who know how to work in extreme weather conditions. They make sure all road components come together perfectly with no gaps or holes when they’re finished since this would lead to huge problems during periods of heavy rain.

These roads also have special drainage systems installed under the pavement, so water doesn’t pool up at high spots causing potholes.

To top everything off, roads that are built on mountains and hills have a special process called “chip sealing” performed after asphalt paving is complete. Bituminous Surface Treatment (or seal coating, BST) is the placement of a protective wearing surface on top of an existing pavement.

This seals the roads to protect them from weathering, which can cause small cracks in the pavement over time if not blocked by an extra layer of protection.

Why Do Roads Wind Around Mountains?

Roads occasionally wind around mountains because roads are built in a way to protect them from water damage. Drilling and blasting mountainsides can also be difficult, and roads that wind around mountains help to avoid this.

Highway engineers build roads based on the physical features of the surrounding landscape, such as hills, mountains, rivers, or swamps, where they must follow specific guidelines called “Standard Highway Geometric Design Procedures” (or SHGD).

These procedures ensure safe design standards are met while protecting road users from adverse conditions related to natural topography and climate variations.

When deciding how best to cross mountainous terrain, the most important factor is safety: crossing at maximum speed with no risk of car accidents caused by dangerous weather conditions like fog or snow.

So roads are designed to avoid the highest points of mountains, which means roads wind around them rather than going straight up and down like a zigzag.

How Long Does It Take To Build Roads on Mountains?

It can take months or even years to build roads on mountains, with lots of planning and preparation beforehand in order for them to be safe when they’re finished.

This will vary depending on how steep the roads are, whether there’s a particular geological feature that affects road placement (such as rivers), or if there are any buildings that might get in the way of roads being built. With all these factors combined, it certainly isn’t an easy process!

Transportation engineers must first find out where roads need to go. They will look at topographical maps of the land, which show elevations (the higher a point is above sea level, the greater its elevation).

Then transportation experts study geological features such as rivers and ravines that might affect road placement before doing any construction work. That way, buildings don’t get in the way of roads or bridges when they’re being built — it just makes everything take longer because engineers have more moving parts involved in their designs for roads!

Once engineers have designed roads using topographical maps featuring elevations and geological features, construction professionals work to plan roads and construct them.

Engineers use a lot of different equipment for roads on mountains, such as:

  • Diggers
  • Dump trucks
  • Semi-trailers
  • Cranes, and
  • Other heavy machinery.

Many roads will involve building temporary airstrips next to mountains first before building roads that lead down into valleys or across peaks.


Building roads on mountains isn’t an easy task. Roads are:

  • Meticulously planned
  • Surveyed and mapped before being formed and paved

The process of blasting holes in the mountainside is necessary for creating roads. This method requires space to be cut into the mountain and then drilled with explosives to create room for new roads that were not previously possible without affecting groundwater sources.

Roads are also blasted when they need to go around curves or up steep slopes, which often creates hazards like landslides and avalanches due to instability. Finally, roads are paved and finished for everyday commuters to utilize.


By Giovanni Valle

Giovanni Valle is a licensed architect and LEED-accredited professional and is certified by the National Council of Architectural Registration Boards (NCARB). He is the author and managing editor of various digital publications, including BuilderSpace, Your Own Architect, and Interiors Place.

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