King Fahad University of petroleum

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King Fahad University of petroleum
MineralsCivil Engineering Department

• CE-576
• Highway Geometric Design
• Chapter I
• Instructor Dr. Nedal T. Ratrout

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Chapter I

• Highway Functions

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Scope

• Introduce the concepts needed
  for understanding the functional
  classification system of highways functions

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Objective

• Systems Classifications.
• Hierarchies of Movements and components.
• Functional Relationships.
• Access Needs Controls.
• Definitions of Urban Rural Areas.

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Objective

• Functional Systems for Rural Areas.
• Functional Highways Systems for Urbanized Areas.
• Functional Classification and Design Type.
• Summary.

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Systems Classifications
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Types of classifications

• Classification by design type
• Based on geometric features (e.g.freeways and
  highways).
• Classification by route numbering
• (e.g.,U.S., state, county), this
  classification is helpful for traffic operations.

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Types of classifications

• Administrative Classification
• (e.g.,National highway system, Non-national
  highway system), used to denote government
  responsibility method of financing
• Functional Classification
• Grouping of highways by the character of
  service they provide, its developed for
  transportation planning design process

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Hierarchies of Movements and Components
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A typical trip includes six stages arranged from
higher to lower based on traffic volume

• Main Movement
• Transition
• Distributor

• Collectors
• Local Access
• Parking

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• Based on traffic generation intensity sometimes
  its desirable to delete intermediate facilities.
• Each element of the functional hierarchy can
  serve as collector facility for the higher
  element.
• By defining the spacing needs traffic volume
  demands, its possible to determine which cases
  should use full system in which cases
  intermediate elements maybe bypassed.

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Functional Relationships
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• The arterial highways generally provide direct
  service between cities large towns.
• Collectors serve small towns directly
  connecting them to the arterial network collect
  traffic from the local roads or distribute
  traffic to the local roads
• Local roads serve individual farms and other
  rural land uses.

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Access Needs and Controls
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• Highways streets network must provide access
  property travel mobility.
• Local Rural facilities provide land access
  function.
• Arterial streets provide mobility.
• Collectors offer balanced service for both
  functions.

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Definitions of Urban and Rural Areas
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• Urban areas are the areas have population between
  5000 to 50,000.
• Rural areas are those areas outside boundaries of
  urban areas.

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Urban Rural areas have different
characteristics with regard to

• Density type of local use.
• Density of street highway networks.
• Nature of travel patterns.
• Rural include more arterials (principal minor)
  but urban include more collectors subdivisions
  of collectors.

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Functional Systems for Rural Areas
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Rural Principal Arterial System

• Corridor movement with trip length density
  suitable for substantial statewide or interstate
  travel.
• Movements between urban areas.
• Integrated movement without stub connection
  except unusual geographic or traffic flow
  dictate.

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Rural Minor Arterial System

• Linkage of cities, large towns and other traffic
  generators.
• Integrated interstate intercounty service.
• Internal spacing consistent with population
  density.
• Corridor movement consistent with items 1 trough
  3 with trip length travel densities greater
  than those served by rural collector or local
  system.

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Rural Collector SystemMajor Collector Roads

• Serve small towns other traffic generators such
  as shipping points, mining agricultural areas.
• Link theses places with nearby larger towns or
  cities or with routs of higher classifications.
• Serve more important travel corridors.

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Rural Collector SystemMinor Collector Roads

• Spaced at intervals consistent with population
  density to accumulate traffic from local roads.
• Provide service to small communities.
• Link locally important traffic generators with
  major collectors.

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Rural Local Road System

• Provide access to the lands and link them with
  the collectors.
• Serve travel with short distance.

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Typical Distribution of Rural Functional System
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Functional Highway Systems in Urbanized Areas
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Urban Principal Arterial System

• Serves major centers of activity, the higher
  traffic volume long trips
• Carries most of trips entering leaving the
  urban area trips between major inner-city
  communities.
• Provides continuity for all rural arterials that
  intercept the urban boundary.

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Urban Principal Arterial System

• 4. Spacing Between principal arterials vary from
  1.6 km 1mi to 8 km 5mi
• 5. Emphasis on offering high mobility.

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Urban Minor Arterial System

• Serves trips of moderate length distributes
  travels to small areas cities.
• Emphasis on offering land access and lower
  mobility.
• Provide urban connection to rural collector
  roads.

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• Spacing from 0.2to1.0km 0.1to0.5mi to 3to5km
  2to3mi, not more than 2km 1mi in fully
  developed areas.
• May carry local bus routs.

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Urban Collector Street System

• Provides both mobility land access.
• Penetrates residential areas.
• Distributes trips from arterial system to the
  local streets collects traffic from residential
  areas channels it into the arterial system.
• May carry local bus routs.

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Urban Local Street System

• Permits direct access to the lands.
• Offers lowest level of mobility.
• Contains no bus routs.

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Length of Roadway travel on Urban Systems
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Functional Classification as a Design Type
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Two major problems arise from using functional
classification system as a design type of highways

• Freeway is normally classified as principal
  arterial while it has unique geometric criteria
  that need design designation apart from other
  arterials.

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• Geometric design criteria capacity levels have
  been based on traffic volume ranges, highways
  with comparable traffic volume provide identical
  level of service, although there maybe
  considerable difference in the function they
  serve.

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Summary
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• Definition of the function of the facility helps
  the designer to determine the level of service to
  fulfill this function then to select design
  speed and geometric criteria.
• The functional concept is important in highway
  planning design, its integrate highway
  planning design process.

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Chapter II

• Design Controls Criteria

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Scope

• Discuss the characteristics of vehicles that act
  as criteria for the optimization or improvement
  in design of highways.

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Objective

• Design Vehicles
• General Characteristics
• Minimum Turning Paths of Design Vehicle
• Vehicle Performance
• Vehicular Pollution

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General Characteristics
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Classes of Design Vehicles

• Passenger Cars
• Include passenger cars of all sizes, sport,
  minivans, vans pick-up trucks.
• 2. Buses
• Include intercity, city transit, school
  articulation buses.
• 3. Trucks
• Include single-unit trucks, truck
  tractor-semitrailer combinations, truck tractor
  with semitrailer in combination with full
  trailer.

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• . Recreational vehicles
• Include motor homes, cars with camper trailers,
  cars with boat trailer, motor homes with boat
  trailers, and motor homes pulling cars.
• Note Bicycles must be considered as a design
  vehicle because its allowed to used on highways.

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• Physical characteristics proportions of
  vehicles using highway are the key controls in
  geometric design (e,g., weight, dimensions,
  operating characteristics)
• In geometric design, designer should consider the
  largest design vehicle that will use the facility.

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When we select design vehicle we have to consider
the following

• Select passenger car when the main traffic
  generator is a parking lot or service of parking
  lots.
• Select single-unit truck for intersection design
  of residential streets park roads.
• Select city transit bus in the design of state
  highway intersections with city streets that have
  few large truck using them.

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• Small bus is selected in the design of small
  streets intersections.
• Select WB-20 WB65 or 67 truck as a minimum size
  design vehicle for intersections of freeway ramp
  terminals with arterial crossroads and
  intersections state highway and industrialized
  street.

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Minimum Turning Paths of Design Vehicles
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• The boundaries of the turning path of each design
  vehicle established by the outer trace of the
  front overhang the path of the inner rear
  wheel. Outer front wheel follows the circular arc
  defining the minimum centerline turning radius
  (CTR).
• Effects of driver characteristics effects of
  slip angle of wheels are minimized by assuming
  the speed of vehicle for the min. turning radius
  is less than 15km/h 10 mph. For higher speed we
  need larger turning radius.

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• Trucks buses have longer wheel bases greater
  min. turning radii than passenger cars.
  Single-unit trucks buses have smaller min.
  turning radii than most combination vehicles.

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Vehicle Performance
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• Acceleration deceleration rates of vehicles are
  often critical parameters in determining highway
  design.
• Based on acceleration deceleration performance
  passenger cars seldom controls design, lower
  performance vehicles are suitable for design
  application such as loaded truck or bus or low
  powered car.

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Vehicular Pollution
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The highway designer should consider the
following sources of pollution in selecting
appropriate transportation alternatives

• Pollutants emitted from motor vehicle
• Noise pollution

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Factors affect the rate of pollutant emission
from vehicles

• Vehicle mix
• Vehicle speed
• Ambient air temperature
• Percentage of vehicles operating in cold mode
• Vehicle age distribution

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Noise pollution is generated by

• Mechanical operation of the vehicle its
  equipment
• Vehicles aerodynamics
• Action of vehicles tires on the pavement
• Sounds of brake
• Exhaust backfires
• Horns
• Sirens of emergency vehicles

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• For passenger cars noise is principally produced
  by the tire-road interaction with some wind
  noise, but for condition of max. acceleration,
  the engine system noise is predominant.
• For trucks noise is produced from exhaust, engine
  gears, fans, air intake, steep grades (cause an
  increase in noise for large trucks), and
  tire-roadway interaction with wind noise. For
  trucks, engine exhaust noise dominate
  tire-roadway interaction for most operating
  conditions.

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Thank you