interchange
DESCRIPTION
TRANSCRIPT
Curves, island, interchanges and freeway
REPORTED BY:JOSEPH R. POLICENABSCE 4-1
Table of content
Widening of curves Islands
Island is included in the design by the ff purposes
Interchange Function of freeway interchanges Types of interchange
Four-way interchanges three-way interchanges two-way interchanges
Freeway entrance and exit
Page 2
Widening of curves
Page 3
Page 4
Provision for a wider roadway is necessary on sharp curve for two lanes pavement
under the ff. reason
1. To force the drivers to shy away from the pavement edge.
2. To increase the effective transverse vehicle width for non-tracking of front and rear wheel.
Page 5
Provision for a wider roadway is necessary on sharp curve for two lanes pavement
under the ff. reason
3. To give additional width due to the slanted position of the front wheel to the roadway center line.
4. For a 7.2m wide roadway, an additional width of 30cm is necessary on an open curve highway.
Islands Is a define area between
traffic lanes for controls of vehicle movement and for pedestrian refuge. Within an intersection, median is considered as an island.
Page 6
Island is included in the design by the ff puRposes
1. Separation of vehicles flow
2. Separation of conflicts
3. Reduction in excessive pavement areas
4. Reduction of traffic and indications of proper use of intersection
Page 7
Island is included in the design by the ff puRposes
5. Arrangement to favor a prominent turning movement
6. Location to traffic control devices
Page 8
General types and shapes of an island
Page 9
General types and shapes of an island
Page 10
General types and shapes of an island
Page 11
Interchange a road junction that typically
uses grade separation, and one or more ramps, to permit traffic on at least one highway to pass through the junction without directly crossing any other traffic stream. It differs from a standard intersection, at which roads cross at grade.
Page 12
The High Five in Dallas, Texas, USA: an extreme example of interchange design. This is a complicated five-level stack interchange due to the proximity of frontage roads.
Page 13
Function of freeway interchanges
To provide separation between two or more traffic arteries.
To facilitate easy transfer of vehicles from one entry to the other or between local roadways and the freeway.
Page 14
Use of overpass or underpass? UNDERPASS Depends on topography,
economy and any other minor factors
Underpass better for deceleration/acceleration, cost and advance warning
OVERPASS Overpass better aesthetics Page 15
Types of interchange
Page 16
Four way interchanges1. Cloverleaf interchange –
typically a two-level, four-way interchange where all left turns are handled by loop ramps (right turns if traveling on the left).
Page 17
A typical cloverleaf interchange in Ohio, United States
Page 18
Advantage of cloverleaf
they require only one bridge, which makes such junctions inexpensive as long as land is plentiful
A major shortcoming of cloverleafs, however, is weaving and the consequent low capacity of this design.
Page 19
Objections to the cloverleaf interchange
design It requires large area of land At higher design speed, more
time is consumed just to transverse the longer loops
Vehicles making left turn execute 270° right turn and travel greater distance becoming very unpleasant and hazardous due to sharp curves and steep grades. Page 20
Objections to the cloverleaf interchange
design Vehicles leaving the curve loop in one quadrant weave those entering the adjacent loop from the through road way.
Page 21
Four way interchanges
2. Stack interchange – whereby left turns are
handled by semi-directional flyover/under ramps.
Page 22
A multi-level stack interchange in Shanghai, China
Page 23
Disadvantages Expensive creates an eyesore among
local residents, leading to considerable (Not In My Back Yard) opposition
Page 24
Four way interchanges3. Cloverstack interchange –
Its ramps are longer to allow for higher ramp speeds, and loop ramp radii are made larger as well. The large loop ramps eliminate the need for a fourth, and sometimes a third level in a typical stack interchange, as only two directions of travel use flyover/under ramps.
Page 25
Page 26
Two way cloverstack Three way cloverstack
1st level
2nd level
1st level 2nd level
3rd level
advantages cheaper to build than stack
interchanges less of an eyesore for local
residents weaving is also eliminated
Page 27
disadvantages require a lot of land to
construct the loop ramps are not as
efficient as flyover/under ramps in terms of traffic flow
Page 28
Four way interchanges4. Turbine interchange (whirlpool)
requires fewer levels (usually two or three) while retaining semi-directional ramps throughout, and has its left-turning ramps sweep around the center of the interchange in a spiral pattern in right-hand driving.
Page 29
The Circle Interchange in Chicago, a notable turbine interchange
Page 30
Page 31
Two way turbine Three way turbine
2nd level
3rd level
1st level2nd level
1st level
Four way interchanges
5. Roundabout interchange – The ramps of the interchanging
highways meet at a roundabout or rotary on a separated level above, below, or in the middle of the two highways.
Page 32
Other/hybrid interchanges
1. windmill interchange is similar to a turbine
interchange, but it has much sharper turns, reducing its size and capacity
Page 34
Page 35
Other/hybrid interchanges
2. diverging windmill increases capacity by
altering the direction of traffic flow of the interchanging highways, making the connecting ramps much more direct.
Page 36
Page 37
Other/hybrid interchanges
3. Divided volleyball create a wide median
between the carriageways of the two interchanging highways, using this space for connecting ramps.
Page 38
Page 39
Other/hybrid interchanges
4. Full diamond large, multi-level
interchanges that use flyover/under ramps to handle both right and left ramps.
Page 40
Page 41
Page 42
Hybrid interchange near Rotterdam, Netherlands.
Hybrid interchange near Cross-Harbour Tunnel,
Hong Kong.
Three way interchanges
Trumpet interchange have been used where one highway
terminates at another highway. These involve at least one loop ramp connecting traffic either entering or leaving the terminating expressway with the far lanes of the continuous highway.
Page 43
A trumpet interchange on the Ottawa River Parkway
Page 44
Three way interchanges
Directional T interchange uses flyover/under ramps in all
directions at a three-way interchange. A semi-directional T does the same, but some of the splits and merges are switched to avoid ramps to and from the passing lane.
Page 45
Semi-directional-T interchange in Lausanne, Switzerland Page 46
Three way interchanges
Full Y interchange typically used when a three-way
interchange is required for two or three highways interchanging in semi-parallel/perpendicular directions, but it can also be used in right-angle case as well. Their connecting ramps can spur from either the right or left side of the highway, depending on the direction of travel and the angle.
Page 47
Two way interchanges Diamond interchange
interchange involving four ramps where they enter and leave the freeway at a small angle and meet the non-freeway at almost right angles.
Page 49
Diamond interchange in Ohio, United States
Page 51
Two way interchanges Parclo interchange/folded
diamond also known as a partial
cloverleaf, is an interchange usually involving four to six ramps, two of which are loop ramps, which connect to the non-highway.
Page 52
Parclo A-4 interchange in Ontario, Canada.
Page 54
Two way interchanges Diverging diamond interchange
similar to a traditional diamond interchange, except that it uses directional lanes for the non-highway to cross over each other on either side of the highway, altering the direction of travel on the over/underpass through the use of traffic lights.
Page 55
This allows all turns to and from the highway to be made without crossing the opposite direction of travel, increasing the capacity when compared to a typical diamond interchange.
Page 56
Page 57
One set of traffic signal
Page 58
References:
Highway engineering by Clarkson H. Oglesby & R. Gary Hicks
Elements of roads and highways by Max Fajardo
www.highway research\interchanges\Interchange (road) - Wikipedia, the free encyclopedia.htm
Page 59