Highways and Highway Components

Highway Transportation Characteristics

Outline

Functional classification of roadsRoad functionsHierarchical structure of road networksMobility vs. accessibilityMobility vs. transportation mode

Highway componentsCross-sectionsHighway plan and profileInterchangesRural and urban intersections

Road Functions

Mobility

Accessibility

Hierarchical Structure of

Road Networks

Rural

Urban

Mobility vs. Accessibility

Road Class Road Function

Freeways Through movement exclusively

Surface Arterials Through movement primary and some land access

Collectors Traffic movement to higher rank roads, access to abutting properties

Local Roads Access to abutting land and local traffic movement

Hierarchical Structure of

Road Networks

Mobility vs. Accessibility

Mobility vs. Transportation Mode

Mobility vs. Transportation ModeCapacity

capacity in veh/h =

capacity in veh/h/lane x number of lanes

capacity in persons/h =

capacity in veh/h x average vehicle occupancy

Mobility vs. Transportation ModeCapacity

Persons/hrVehicles/hrFacility6,000 x 1.7 = 10,2002,000 x 3 = 6,000Three-lane urban freeway

2,400 x 1.7 = 4,080800 x 3 = 2,400Three-lane urban arterial

100 x 80 = 8,000100 x 1 =100One lane of buses

19,000One track of light rail

40,000One track of heavy rail

Mobility vs. Transportation ModeCapacity

Highway ComponentsCross-section

Highway Components

Highway plan and profile

Highway Components

Urban Intersections

Picture

Highway Components Rural Intersections

Picture

Highway Components

Interchanges

DiamondCloverleaveUrban directional