Roads consist of one or two roadways (British English: carriageways), each with one or more lanes and any associated sidewalks (British English: pavement) and road verges. ... Other names for roads include parkways, avenues, freeways, tollways, interstates, highways, or primary, secondary, and tertiary local roads.

Primary System of Roads

The primary system of roads typically refers to the major road network within a country or region that connects major cities, towns, and economic centers. It is the backbone of transportation infrastructure and plays a crucial role in facilitating the movement of people and goods. In this context, the primary system of roads consists of both national highways and expressways.

1. National Highways:
National highways are arterial roads that connect major cities and towns within a country. These roads are typically longer and wider compared to other roads, as they are designed to handle heavy traffic volumes. National highways are usually maintained and developed by the central government or a designated national highway authority.

Key features of national highways include:

- High traffic volume: National highways usually experience heavy traffic flow, including commercial vehicles, passenger cars, and public transportation.
- Connectivity: They connect major cities, state capitals, industrial hubs, tourist destinations, and ports, facilitating regional and national connectivity.
- Four-lane or more: National highways often have multiple lanes, with four-lane or six-lane configurations to accommodate a large number of vehicles.
- Controlled access: National highways may have controlled access points, such as interchanges and flyovers, to ensure smooth traffic flow and reduce congestion.
- Design standards: These roads are designed according to specific design standards, considering factors such as traffic volume, terrain, and safety requirements.

2. Expressways:
Expressways, also known as freeways, motorways, or tollways, are high-speed roads designed for uninterrupted and safe travel. They are characterized by limited access points, high design standards, and controlled entry and exit ramps. Expressways are typically maintained by a dedicated authority, and they often require toll payments for usage.

Key features of expressways include:

- High-speed travel: Expressways are designed for high-speed travel, with minimum speed limits and limited access points to ensure smooth traffic flow.
- Limited access: Expressways have controlled entry and exit points, usually through ramps, to minimize interruptions and enhance safety.
- Separation of traffic: These roads often have a median barrier or divider to separate opposing traffic flows and reduce the risk of head-on collisions.
- Grade separation: Expressways often have grade-separated interchanges, flyovers, and underpasses to eliminate intersections and streamline traffic movement.
- Advanced safety features: They may include features such as crash barriers, lighting, signage, and surveillance systems to enhance safety.

In summary, the primary system of roads consists of both national highways and expressways. National highways serve as the major road network connecting cities and towns, while expressways provide high-speed, limited-access routes for faster and safer travel. These two types of roads work together to form a comprehensive transportation network, facilitating regional and national connectivity.

There are three type of road classified on the basis of third road development plan .
1:- primary , 2:- Secondary 3:- tertiary
primary road is classified in two types .
a:- Express highway and
b :- National highway