Chapter 1: Highway Functions

1. Chapter 1: Highway Functions Objectives: • Be able to state the four major highway classification types • Be able to identify the six stages of most trips. • Be able to define urban and rural areas and urbanized areas and small urban areas • Be able to state the four functional classes of highways • Be able to state the characteristics of the functional classes of rural and urban highways.

2. 1.1 Four Highway Classification Types • Design Types: Freeways, highways, conventional streets • Route Numbering: Interstate, US routes, State primary, State secondary, county, etc. • Administrative Classification: State federal aid primary and secondary, state primary and secondary • Functional Classification: • Rural Roads: Principal arterial, Minor arterial, Collector, Local road • Urban Roads: Principal arterial, Minor arterial street, Collector street, Local street Why classification so important? It is the first step in the highway design process  Define the function that the facility is going to serve.

3. Factors Influencing Highway Design • Functional class of the highway being built • Cross section elements, Pavement structure, and Vehicle types using the highway • Expected traffic volume and vehicle mix • Design hourly volume, Design vehicle • Design speed • Topography of the area • LOS to be provided • Available funds • Safety • Social and environmental factors

4. 1.2.1 The Concept of Functional Classification • Hierarchies of Movements and Components – check your driving routine • 6 stages: • Main movement, transition, distribution, collection, access, and termination • The movement hierarchy is based on the total amount of traffic volume Termination (Figure 1-1) Do you always have to go through these 6 stages? What happens when a lower volume facility has a capacity problem?

5. 1.2.1 The Concept of Functional Classification (cont) • Hierarchies of Movements and Components – check your driving routine • 6 stages: • Main movement, transition, distribution, collection, access, and termination • The movement hierarchy is based on the total amount of traffic volume

6. 1.2.2 Functional Relationships • Functional classification groups streets and highways according to the character of service they are intended to provide. (Figure 1-2)

7. 1.2.2 (cont): Rural vs. Urban Urban highway system Rural highway system (Figure 1-4) (Figure 1-3)

8. Principal arterials Minor arterials Major collectors Minor collectors Local roads and streets 1.2.3. Access Needs and Controls Mobility Access (Figure 1-5) Mobility = the ability to travel to many different destinations Accessibility = the ability to gain entry to a particular site or area

9. 1.3 Functional System Characteristics • Urban and rural areas have fundamentally different characteristics with regard to density and types of land use, density of street and highway networks, nature of travel patterns, and the way in which these elements are related. Hence, they are classified separately. • Urban vs. Rural?: Urban if population ≥ 5,000. • Urban areas are subdivided into “urbanized areas (population ≥ 50,000) and “small urban areas (population between 5,000 and 50,000)”

10. 1.3.3 Functional system of rural roads Utah County Rural Highways

11. Typical Distribution of Rural Functional Systems (Table 1-1) Let’s look at a Utah state highway map to see if this is true.

12. 1.3.4 Functional system of urban roads Provo-Orem area St. George