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 (local), 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. Gated Community? Not a good idea

8. 1.2.2 (cont): Rural vs. Urban Urban highway system
Rural highway system
(Figure 1-4)
(Figure 1-3)

9. Payson - Santaquin - Genola

10. 1.2.3. Access Needs and Controls
Principal arterials
Minor arterials
Major collectors
Minor collectors
Local roads and streets
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

11. 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)”

12. 1.3.3 Functional system of rural roads
Principal arterials
Serves mostly interstate trips and a substantial amount of intrastate trips
I-15, I-70, I-80, I-215, US89, US40, US6, US191, etc.
Minor arterials
Augments the principal arterials, connects cities, large towns, other large traffic generators
SR73,10, 130, 257, 56, etc.
Major collectors
Carry traffic to and from county seats and large cities not served by the arterial system
SR21, 24, 95, 18, 12, etc.
Minor collectors
Collects traffic from local roads and convey it to other facilities
SR174, 124, 96, etc.
Local roads
All roads within the rural area not classified above
All others
Utah County Rural Highways

13. Typical Distribution of Rural Functional Systems
(Table 1-1)
System
Percentage of total rural road length
Principal arterial
PA + Minor arterial
Collector road
Local road system
2-4%
6-12% (mostly 7-10%)
20-25%
65-75%
Let’s look at a Utah state highway map to see if this is true.

14. 1.3.4 Functional system of urban roads
Urban principal arterials
Serves the major activity centers: Interstate, expressways, other principal arterials (Interstate, Other freeways, & other principal arterials)
I-15, State St., University Ave., University Parkway, 900E, Center St.
Urban minor arterials
Interconnect with and augment principal arterials
Bulldog Ave (1230N), Freedom Blv., Geneva Rd.
Urban collector streets
Collect traffic from local streets and convey it to the arterial system
Canyon Rd., Timpview, 500N, 800N
Urban local streets
All other streets
That’s where your house is.
Provo-Orem area
St. George