How a Road is Built

how a road is built

You’re probably on the road at least a few times a day. Commuting to and from work. Transporting your children from one after-school activity to the next. Traveling to the store for a few groceries. However, most of us give little thought to the roads we travel, often taking the freedom they provide us for granted – at least until they are closed for repairs, washed out in a flood, or in some way rendered impassable.

Amid our grumbling about potholes, traffic jams and incompetent drivers, we forget just how fortunate we truly are. The public transportation system wasn’t always there! Roads, highways, and interstates were built, and continue to be built for a number of reasons, including increasing populations, the need for jobs, and attracting companies. If you’ve ever wondered HOW roads are constructed, this read is for you!


The first step in building a road is planning. Surveyors, engineers, environmentalists, landscape architects, and others identify trends that determine what and how to build. Existing development and land use plans, current road conditions, traffic volumes, crash statistics, possible environmental impacts, and cost and revenue estimates are all taken into consideration. This phase can take anywhere from 1 to 24 months.


Phase 2, the scoping phase generally lasts between 1 and 8 months depending on project complexity, and includes: confirming the project purpose and need; initiating the environmental review processes; determining what permits are required; identifying stakeholders; establishing the project team; holding the initial scoping team meeting; performing surveys; developing the initial design; and evaluating public involvement.


The scoping phase consists of two parts – preliminary and detailed – and generally lasts between 1 and 30 months. This phase includes designing the roadway, structures and bridges; placing traffic control devices; determining right of way and utility impacts; performing “constructability” and work zone reviews; completing the environmental documentation required by NEPA; holding public hearings; and obtaining design approval.


Earthwork is one of the most important elements in road construction because it establishes a stable foundation. A roadway with a substandard foundation will fail prematurely. That is why the road’s base layers are as equally important as the finished surface. To complete the earthwork, layers of 12-inch gravel is laid on the road bed, then moistened and compacted. This phase generally last 1 to 36 months.


After passing strict inspections the road bed is ready for paving. In Arizona, most roadways are built using asphalt, as asphalt has been proven to be cost effective, reduce noise pollution, and increase driver comfort. Asphalt uses bitumen, a petroleum product, to glue together sand and crushed rock. This mixture is heated to approximately 300 degrees. Workers then spread and compact the hot mixture onto the roadway.


Once the road has been built, and passed strict inspections including ride quality testing, it is returned to the motorists.

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