Transcript ECGD4228-2 - جامعة فلسطين

ECGD4228
Transportation Engineering II
Second Semester 2009 - 2010
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Part 1
 Course Overview (Syllabus)
 Introduction to Pavement Engineering
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Transportation Engineering
 Highway Systems
 Airway Systems
 Railway Systems
 Maritime Systems
 Pipeline Systems
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Principles of Highway Engineering
 Pavement classification
 Design speed
 Design vehicle
 Route surveys
 Earth works
 Geometric alignments
 Cross-sections
 Drainage systems
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Categories of Highway Engineering
 Rural highways
 Urban highways
 Connectors
 Interchanges
 Intersections
 Parking facilities
 Multi users
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Phases of Pavement Engineering
 Planning (Demands & Alternatives)
 Considerations & Constraints
 Design (Instant & Futuristic)
 Construction (Cost & Time)
 Operational Management
 Development Studies
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Location & Route Selection Components
 Detailed layout of selected route
 Detailed elements of geometric alignment
 Positions of structures & drainage systems
 Positions of special requirements & Utilities
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Geometric Design
 Horizontal alignments
 Vertical alignments
 Transitional alignments
 Cross sections
 Intersections
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Referential Web Sites
 American Association of State Highway &
Transportation Officials (AASHTO)
www.transportation.org
 Institute of Transportation Engineers (ITE)
www.ite.org
 Transportation Research Board (TRB)
www.trb.org
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Part 2
 Horizontal Alignments
 Geometric Parameters
 Sight Distances
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Route Plan & Profile
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Surveying & Stationing
 Staking: to define the geometry of a
route by marking cross-sections for the
horizontal and vertical positions along the
route at equal distances.
 Stationing: to start from an origin point
by stationing (0). Regular stations are
established every 100 ft (≈ 30 m).
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Types of Horizontal Curves
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Types of Horizontal Curves
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Geometric Design
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Geometric Design
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Geometric Design
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Distribution of e & f
 Method 1: e and f are based on the design
speed and linearly directly proportioned to the
inverse of the radius (i.e., Rmin ≤ R < ∞).
 Method 2: f is first set as fmax. For sharper
curves, f remains at fmax and e is then used to
sustain the excess lateral acceleration until it
reaches emax. In this method, first f and then e
are increased in inverse proportion to R.
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Distribution of e & f
 Method 3: e is first set as emax. For sharper
curves, e remains at emax and f is then used to
sustain the excess lateral acceleration until it
reaches fmax. In this method, first e and then f are
increased in inverse proportion to R.
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Distribution of e & f
 Method 4: This method is the same as method
3, except that it is based on the average running
speed instead of the design speed.
 Method 5: e and f are in a curvilinear relation
with the inverse of R, with values between those
of methods 1 and 3.
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Distribution of e & f
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Distribution of e & f
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Distribution of e & f
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Horizontal Sight Distance
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Horizontal Sight Distance
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Setting Out horizontal Curves
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Setting Out horizontal Curves
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Setting Out horizontal Curves
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Setting Out horizontal Curves
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Key Design Steps
1.
2.
3.
4.
5.
6.
7.
Assign a maximum superelevation rate.
Assign a maximum side-friction factor.
Calculate the minimum radius of curving.
Iterate for several different radii.
Stopping sight distance is to be valid.
Check for the passing sight distance.
Design the transition segments.
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Transition Curves
 Transition curves provide easy-to-follow path
for drivers by gradually changing the road
cross section from normal to superelevated.
 Centrifugal forces fade gradually as a vehicle
enters or leaves a horizontal curve.
 Spirals facilitate the transition in width where
the traveled way section is to be widened
around a horizontal curve.
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Transition Curves
 Euler spirals are generally used for horizontal
transition alignments.
 The radius varies from infinity at the tangent
end of the spiral to the radius of the horizontal
curve at the circular curve end.
 Drainage facilities are a major issue while
considering the cross-section options.
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Transition Curves
L = (0.0702V3)/(RC)
where:
L = minimum length of spiral, m;
V = speed, km/h;
R = curve radius, m; and
C = rate of centripetal acceleration increase,
m/s3.
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Transition Curves
 The factor C is an empirical value indicating
the comfort and safety involved. The value of 1
is generally accepted for railroad operation.
The values ranging from 1 to 3 have been used
for highways. A more practical control for the
length of spiral is the length required for
superelevation runoff.
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Superelevation Runoff
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Due to next lecture:
 Study this lecture (AASHTO 2001 – Ch. 3)
 Review geometric alignments (Practical)
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