The Types of Roads and Their Purposes
Roads are one of the most necessary things that keep our societies running. Without them, life would come to a screeching halt. They allow for the transport of goods and services as well as a method of transport to bring our world closer together. Higher amounts and densities of roads are correlated to higher Gross Domestic Products of nations (GDP) which is commonly used as a metric in measuring the standard of living. Roads come in many shapes and forms and serve a variety of purposes. Roads can be categorized into many different groups. Some of the most prevalent would be Motorway, Trunk, Primary, Secondary, Tertiary and Residential. Each of these five categories will be explained further as well as some of their uses and where you might find them in the real world
Motorways are usually the most important and influential highways in countries. They have at least 2 lanes in the same direction. Other than Motorway, they are commonly refered to as freeways, expressways, interstate and throughways. If there is an opposing flow of traffic on the road, it will be divided by a barrier. These roads can be viewed as the central ateries of road structures. It is popular to use smaller roads to gain access to large motorways, then use smaller roads to get to an individual's final destination. One of the requirements of Motorways are their limited immediate access to residential roads. Motorways are typically associeted with speed limits as their lanes are wide and there are very few sharp turns. One of the most famous motorways is the German Autobahn, which has no speed limit. This road is viewed as one of the main corridors through Germany and much of the nations commerce travels through this road.
Trunks are a step down from Motorways in size and scale. They are still highly essential to any road network and are used in the transit of many commerce related activities. Trunks are mainly defined as important roads that are similar to, but not, Motorways. Unlike motorways, they are not as limited in the roads they can immediately serve but are intended for lost distance traffic. They commonly have dividers between opposing flows of traffic if they are nearby
Primary roads are catagorized by purpose of directly connecting large towns. They can be anywhere from two to eight lanes.When viewing a large network of roads, primary roads can cause a 'spiderweb' appearance of roads that immediately connect two large populaiton centers. These roads are not seperated by a physical barrier but sometimes can be separated by a grass strips. Most commonly they are not separated at all between the two oncoming traffic lanes. Many lower-tier roads can branch off of primary roads. It is not uncommon to also see traffic lights on these types of roads when they intersect other roads.
Secondary roads are usually not part of a major route between cities. They can lead to higher tier roads but by themselves, it is hard to get to major population centers without connecting to higher-tier roads. Secondary roads have lower speed limits than the other higher-tier roads. These types of roads can have anywhere between 1 and 2 lanes in one direction and will not have any type of separation between the different flows of traffic. These roads could have many twists and turns and immediately connect with other roads. They will also have many stoplights or even four-way stops if necessary.
These roads are mostly used for connecting small population centers together or important centers within larger cities. Many residential roads will connect to tertiary roads. Tertiary roads will have a mix of residential, commercial and sometimes industrial structures adjacent to the road itself.
By far the most common road in road networks, residential road's primary purpose is to allow housing to access the greater road network. They are not intended to be used as a method of travel, but more as a route of access to higher-tier roads. Residential roads will commonly have stoplights and stop-signs as well as low speed limits.
Liu, B., Shi, Y., Li, D., Wang, Y., Fernandez, G., & Tsou, M. (2020). An Economic Development Evaluation Based on the OpenStreetMap Road Network Density: The Case Study of 85 Cities in China [Abstract]. International Journal of Geo-Information. doi:10.3390/ijgi9090517
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