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    Roundabout Design Parameters

    Uploaded by

    avhnmurthy
    The document describes three types of roundabouts: mini, compact, and normal (two-lane). Mini roundabouts have a low-level central island and are for local roads only. Compact roundabouts can accommodate minor collector roads and have a raised central island. Normal (two-lane) roundabouts are for major/minor collector roads and have two lanes on all entries/exits as well as flared entries and exits. The document provides design parameters for each type, including dimensions for inscribed circle diameter, entry/exit widths and radii, entry angles, and more.

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    © All Rights Reserved
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    Roundabout Design Parameters

    Uploaded by

    avhnmurthy
    226 views7 pages
    The document describes three types of roundabouts: mini, compact, and normal (two-lane). Mini roundabouts have a low-level central island and are for local roads only. Compact roundabouts can accommodate minor collector roads and have a raised central island. Normal (two-lane) roundabouts are for major/minor collector roads and have two lanes on all entries/exits as well as flared entries and exits. The document provides design parameters for each type, including dimensions for inscribed circle diameter, entry/exit widths and radii, entry angles, and more.

    Original Description:

    RAB

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    The document describes three types of roundabouts: mini, compact, and normal (two-lane). Mini roundabouts have a low-level central island and are for local roads only. Compact roundabouts can accommodate minor collector roads and have a raised central island. Normal (two-lane) roundabouts are for major/minor collector roads and have two lanes on all entries/exits as well as flared entries and exits. The document provides design parameters for each type, including dimensions for inscribed circle diameter, entry/exit widths and radii, entry angles, and more.

    Copyright:

    © All Rights Reserved
    Download as PPTX, PDF, TXT or read online from Scribd
    Download as pptx, pdf, or txt
    226 views7 pages

    Roundabout Design Parameters

    Uploaded by

    avhnmurthy
    The document describes three types of roundabouts: mini, compact, and normal (two-lane). Mini roundabouts have a low-level central island and are for local roads only. Compact roundabouts can accommodate minor collector roads and have a raised central island. Normal (two-lane) roundabouts are for major/minor collector roads and have two lanes on all entries/exits as well as flared entries and exits. The document provides design parameters for each type, including dimensions for inscribed circle diameter, entry/exit widths and radii, entry angles, and more.

    Copyright:

    © All Rights Reserved
    Download as PPTX, PDF, TXT or read online from Scribd
    Download as pptx, pdf, or txt
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    At a glance
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    The passage discusses different types of roundabouts and their design parameters.

    Mini roundabout, compact roundabout, and normal roundabout are mentioned.

    Compact roundabouts have single lane entries and exits on all legs and service minor collector and local roads. They have raised islands with truck aprons.

    TYPES OF ROUNDABOUT

    1.

    MINI ROUNDABOUT

    2.

    COMPACT ROUNDABOUT

    3.

    NORMAL ROUNDABOUT

    MINI ROUNDABOUT

    KEY FEATURES:
    One leg on all Arm
    Local Roads only
    Central Island Low Level
    Mountable Curb

    DESIGN PARAMETERS:
    ICD 18-22m
    Circular Roadway 4-5 m
    No Flaring for Entry and Exit Lane
    Entry Curb Radius: 6 m (Minimum)
    Exit Curb Radius: 6 m to 20 m
    Entry/Exit width 3.0 m
    Entry Path Radius: No max value

    COMPACTROUNDABOUT

    KEY FEATURES:
    Single lane Entries & Exit on all
    legs.
    Minor collector, service,Local Roads
    Raised island with Truck apron

    DESIGN PARAMETERS:
    Minimum ICD : 28 m
    Entry Curb Radius: 10 m (Minimum)
    Exit Curb Radius: 15 m to 20 m
    Entry/Exit width 4.5 m
    Entry Angle: 20 to 60 degree
    (Optimum 30-45 )
    Entry Path Radius: Max 70 m
    Flare Length : 5.0 m (minimum)

    TWO - LANE ROUNDABOUT

    KEY FEATURES:
    Major and Minor collector, local
    Raised island with Truck apron
    Flare Entries and exits, allowing two vehicle to
    enter /Exit
    Two lane on all entries
    No more than two Exit Lane

    DESIGN PARAMETERS:
    Minimum ICD : 28 m
    Circulatory roadway : 6 to 10 m
    Entry Curb Radius: 10 m (Minimum)
    Exit Curb Radius: 20-100 m (Minimum)
    Entry Angle: 20 to 60 degree
    (Optimum 30-45 )
    **Circulatory Roadway Width : 1.0 to 1.2 X Max. Entry Path Radius: Max 100 m
    Entry Width

    Exit Width : QHDM 6.10.13


    Single lane : 7.0 m to 7.5 m (wide
    Single Exit)
    Dual Lane : 10 to 11 m(Wide two
    lane)
    Taper : 1:15 to 1:20

    Entry Width & Flare Length

    Effetive Flare Length:

    Average length over which the entry


    widens.
    Minimum 5m in urban Area
    25 m in Rural Area

    ** Effective flare length greater than 25 m may


    improve the geometric layout but little
    effect on Capacity

    F'

    V=Approach Half Width

    1800

    1400

    1600

    1200

    1400

    1000

    1200

    800

    1000

    600

    0 1 2 3 4 5 6 7 8
    HALF WIDTH (V)

    1400

    4 5 6 7 8 9 10 11
    ENTRY WIDTH

    1200

    C
    A
    P
    A
    C
    IT
    Y

    C
    A
    P
    A
    C
    I
    T
    Y

    C
    A
    P
    A
    C
    I
    T
    Y

    1000

    800

    600
    0 10 20 30 40 50 60 70 80
    FLARE LENGTH

    Entry Angle

    Angle between Entering and


    Circulating Traffic streams.
    Angle should lie between 20
    and 60 degree (optimum 3045 degree)

    1400

    1200
    C
    A
    P
    A
    C
    IT
    Y

    1000

    800
    0 20

    40 60 80 100
    ENTRY ANGLE

    Entry Path Radius

    Entry Path Radius


    Mini Roundabout: No max value
    Compact Roundabout: Max 70 m
    Two lane Roundabout: Max 100 m

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