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Chapter 1: Highway FunctionsChapter 1: Highway Functions

Be able to state the four major highway classification typesBe able to state the four major highway classification types

Be able to identify the six stages of most trips.Be able to identify the six stages of most trips.

Be able to define urban and rural areas and urbanized areas and Be able to define urban and rural areas and urbanized areas and small urban areassmall urban areas

Be able to state the four functional classes of highwaysBe able to state the four functional classes of highways

Be able to state the characteristics of the functional classes of rural Be able to state the characteristics of the functional classes of rural and urban highways.and urban highways.

Objectives:

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1.1 Four Highway Classification Types1.1 Four Highway Classification Types

Design TypesDesign Types: : Freeways, highways, conventional streetsFreeways, highways, conventional streets

Route NumberingRoute Numbering: : Interstate, US routes, State primary, Interstate, US routes, State primary, State secondary, county, etc.State secondary, county, etc.

Administrative ClassificationAdministrative Classification: : State federal aid State federal aid primary and secondary, state primary and secondaryprimary and secondary, state primary and secondary

Functional ClassificationFunctional Classification::– Rural Roads: Rural Roads: Principal arterial, Minor arterial, Collector, Principal arterial, Minor arterial, Collector,

Local roadLocal road

– Urban Roads: Urban Roads: Principal arterial, Minor arterial street, Principal arterial, Minor arterial street, Collector street, Local streetCollector 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.

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Factors Influencing Highway DesignFactors Influencing Highway Design

Functional class of the highway being builtFunctional class of the highway being built– Cross section elements, Pavement structure, and Cross section elements, Pavement structure, and

Vehicle types using the highwayVehicle types using the highway

Expected traffic volume and vehicle mixExpected traffic volume and vehicle mix– Design hourly volume, Design vehicleDesign hourly volume, Design vehicle

Design speedDesign speedTopography of the areaTopography of the areaLOS to be providedLOS to be providedAvailable fundsAvailable fundsSafetySafetySocial and environmental factorsSocial and environmental factors

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1.2.1 The Concept of Functional 1.2.1 The Concept of Functional ClassificationClassification

Hierarchies of Hierarchies of Movements and Movements and Components – check Components – check your driving routineyour driving routine

6 stages:6 stages:– Main movement, transition, Main movement, transition,

distribution, collection, distribution, collection, access (local), and access (local), and terminationtermination

The movement hierarchy The movement hierarchy is based on the total is based on the total amount of traffic volumeamount of traffic volume

Do you always have to go through these 6 stages?

What happens when a lower volume facility has a capacity problem?

Termination

(Figure 1-1)

1.2.1 The Concept of Functional Classification (cont)1.2.1 The Concept of Functional Classification (cont)

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Hierarchies of Hierarchies of Movements and Movements and Components – Components – check your check your driving routinedriving routine

6 stages:6 stages:– Main Main

movement, movement, transition, transition, distribution, distribution, collection, collection, access, and access, and terminationtermination

The movement The movement hierarchy is hierarchy is based on the based on the total amount of total amount of traffic volumetraffic volume

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1.2.2 Functional Relationships1.2.2 Functional Relationships

Functional Functional classification groups classification groups streets and highways streets and highways according to the according to the character of service character of service they are intended to they are intended to provide. provide.

(Figure 1-2)

Gated Community? Not a good ideaGated Community? Not a good idea

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1.2.2 (cont): Rural vs. Urban1.2.2 (cont): Rural vs. Urban

Rural highway system Urban highway system

(Figure 1-3) (Figure 1-4)

Payson - Santaquin - GenolaPayson - Santaquin - Genola

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1.2.3. Access Needs and Controls1.2.3. Access Needs and Controls

Mobility

Access

Principal arterials

Minor arterials

Major collectors

Minor collectors

Local roads and streets

Mobility = the ability to travel to many different destinations

Accessibility = the ability to gain entry to a particular site or area

(Figure 1-5)

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1.3 Functional System Characteristics1.3 Functional System Characteristics

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

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1.3.3 Functional system of rural roads1.3.3 Functional system of rural roadsPrincipal 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

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Typical Distribution of Rural Typical Distribution of Rural Functional SystemsFunctional Systems

SystemSystem Percentage of total rural road lengthPercentage of total rural road length

Principal arterialPrincipal arterial

PA + Minor arterial PA + Minor arterial

Collector roadCollector road

Local road systemLocal road system

2-4%2-4%

6-12% (mostly 7-10%)6-12% (mostly 7-10%)

20-25%20-25%

65-75%65-75%

Let’s look at a Utah state highway map to see if this is true.

(Table 1-1)

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1.3.4 Functional system of urban roads1.3.4 Functional system of urban roadsUrban 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