Traffic Exposure Classifications

Traffic Category

Category

Exposure Description

High

·

Structure or Route located at or is adjacent to features (e.g. junctions, interchange, etc.) that frequently impose obstructions to traffic flow (i.e. resulting in queuing/slow moving traffic).

·

Speed limit >40mph, with poor horizontal and vertical alignment  (e.g. uneven carriageway, located on/near a bend or gradient, etc.)

·

High Annual Average Daily Traffic (e.g. AADT > 25,000 vehicles)

·

High volume of Commercial Vehicles (e.g. CV > 2,500 vehicles)

·

High volume of Heavy Goods Vehicles

Moderate

·

Structure or route is located at or is or adjacent to features (e.g. junctions, interchange, etc.) that occasionally impose obstructions to traffic flow (i.e. resulting in queuing/slow moving traffic).

·

Speed limit >20mph to ≤40mph, with poor horizontal and vertical alignment (e.g. uneven carriageway, located on/near a bend or gradient, etc.)

·

Medium Annual Average Daily Traffic (e.g. AADT > 10,000 to ≤ 25,000 vehicles)

·

Medium volume of Commercial Vehicles (e.g. CV > 1,000 to ≤ 2,500 vehicles)

·

Medium volume of Heavy Goods Vehicles

Low

·

Structure or route or is or adjacent to features do not impose obstructions to traffic flow

·

Speed limit ≤20mph, with  good horizontal and vertical alignment (e.g. even carriageway, level and straight stretch route).

·

Low Annual Average Daily Traffic (e.g. AADT≤ 10,000 vehicles)

·

Low volume of Commercial Vehicles (e.g. CV ≤1,000 vehicles)

·

Low volume of Heavy Goods Vehicles

Note: It is considered that the traffic category would be influenced by the frequency, speed and concentration of traffic flows (especially HGVs) and would be dependend on the location, e.g. rural, urban, etc.