ECGD4228-2 - جامعة فلسطين
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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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