Hierarchy of roads

The hierarchy of roads organizes the functions of different types of roads. While sources differ on the exact nomenclature; in general, they describe the same hierarchy.

Contents

1 Freeways 2 Arterials 3 Collectors 4 Local roads 5 History 6 Access management 7 External links

Freeways

At the top of the hierarchy are limited access roads or freeways, including most toll roads. These roads provide largely uninterrupted travel, often using partial or full access control, and are designed for high speeds. Some freeways have collector/distributor roads or even more extensive local lanes (also known as collector/distributor lanes) which further reduce the number of access ramps that directly interface with the freeway, rather the freeway periodically interfaces with these parallel roadways, which themselves have multiple on and off-ramps. These allow the freeway to operate with less friction at an even higher speed and with higher flow. Often freeways are included in the next category, arterials.

Arterials

The next level are arterials, In general arterials are major through roads that are expected to carry large volumes of traffic. Arterials are often divided into major and minor arterials, and rural and urban arterials.

In some places there are large divided roads with few or no driveways that cannot be called freeways because they have occasional at-grade intersections (expressways in California) or they are just too short (superarterials in Nevada). Such roads are usually classified as arterials.

Collectors

These are followed by collectors (not to be confused with collector/distributor roads, which reduce weaving on freeways), which act to collect traffic from local roads and distribute it to arterials. Traffic using a collector is usually going or coming from somewhere nearby.

Local roads

At the bottom of the hierarchy are local roads . These roads have the lowest speed limit, and carry low volumes of traffic.

History

Roads have been distinguished by function probably since their beginning, and the hierarchy of roads was firmly established by the time of the Roman Empire.

Access management

The related concept of access management aims to provide access to land development while ensuring traffic flows freely and safely on surrounding roads. Frontage roads are often used to reduce the conflict between the high-speed nature of an arterial and property access concerns.

External links

• FHWA - Functional Classification
• Florida Intrastate Highway System, an example of a statewide system of major arterials