Junction Design(Rekabentuk Persimpangan)

Disediakan oleh:Fadilah binti Mohd

Define Junction(Maksud Persimpangan)

• Refer to the land area where two or more highways meet or intersect with or cross each other.

• Persimpangan merujuk kepada sebuah kawasan tempat dua atau lebih daripada dua lebuh raya menyilang atau memintas.

Define Junction(Maksud Persimpangan)

• Junctions are designed so that drivers can cross traffic streams or move from one traffic stream to the other in an attempt to change direction of movement.

• Persimpangan direkabentuk untuk membolehkan pemandu menyeberangi arus lalulintas lain atau beralih dari satu arus ke arus yang lain untuk menukarkan arah pergerakannya.

Factors that affect junction load

Dua faktor yang mesti diselaraskan di dalam rekabentuk persimpangan ialah:(i) Rekabentuk geometri aspek-aspek fizikal.

- Merangkumi: jumlah & lebar lorong, rekabentuk penyaluran, jejari memusing dll

(ii) Teknik kawalan lalulintas.- Merangkumi teknik-teknik spt kawalan

berhenti @ alah, bulatan & lampu isyarat.

Types of JunctionsTypes of at grade junction• Junction without

signage/control• Priority junction• Priority junction with

routing• Roundabout with or

without traffic light• Traffic light controlled

junction• Tiered junction

Types of interchange• Trumpet interchange• Diamond interchange• Cloverleaf interchange

Junction without signage/control(persimpangan tanpa tandaan/kawalan)

• Tanpa lampu isyarat maka ia dikawal oleh tanda-tanda kawalan lalulintas spt tanda BERHENTI & tanda BERI LALUAN

Digunakan aliran lalulintas di jln major agak tinggi

Diletakkan di bahagian tanjakan persimpangan yang mempunyai aliran kenderaan yang rendah

Priority junction (persimpangan keutamaan)

• Takrif persimpangan keutamaan: jalan utama (major: isipadu, nilai unsur rekabentuk geometri lebih tinggi) diberikan keutamaan dibandingkan dengan minor kecuali di kws. perumahan, bulatan dan berlampu isyarat. Untuk persimpangan T dan tak serentak, bhgatas T diberikan keutamaan.

• Jenis persimpangan keutamaan(i) Persimpangan tee (ii) Persimpangan bersilang(iii) Persimpangan tak serentak (staggered)

Priority junction with routing (persimpangan dengan penyaluran)

• Teknik memisahkan dua @ lebih daripada dua arus lalulintas suapay tiap-tiap arus bergerak di dalam sesuatu saluran @ lorong melalui pulau lalulintas timbul @ tanda-tanda turapan disebut penyaluran.

• Teknik penyaluran boleh diambil guna jika luas kawasan persimpangan yang sedia ada memadai, kadar kemalangan tinggi, laju serta isipadu lalulintas tinggi & pejalan kaki perlu dilindungi.

Roundabout with or without traffic light(bulatan dengan lampu isyarat atau tanpa lampu isyarat)

A roundabout is a type of circular intersection, a junction in which road traffic flows in one direction around a central island. In a roundabout, entering traffic must always yield to traffic already in the circle, and roundabouts have additional restrictions on the junction layout to give high safety.

Traffic light controlled junction(persimpangan kawalan lampu isyarat)

• Arus lalulintas dipisahkan oleh masa.• Peningkatan isipadu lalulintas dan kegiatan

memusing, sistem kawalan berlampu isyarat diperlukan.

• Sesuai di dalam kes kesemua cabang lebuh raya yang menanggung isipadu lalulintas yang sangat tinggi.

Tiered junction(persimpangan bertingkat)

• Bermaksud kawasan persimpangan @ kemudahan yang menyilang yang terletak pada aras yang berbeza.

• Konflik arus lalulintas diasingkan oleh perbezaan aras.

• Dibina bertujuan untuk memenuhi kriteria kawalan masuk penuh iaitu pada lebuh raya yang nilai laju rekabentuknya tinggi.

Tiered junctionJenis persimpangan bertingkata) Persimpangan 3 cabang

i) Persimpangan Tii) Persimpangan Yiii) Persimpangan separa bulataniv) Persimpangan separa kelawar

b) Persimpangan 4 cabangi) Persimpangan intanii) Persimpangan kelawariii) Persimpangan separa kelawariv) Persimpangan berbulatanv) Persimpangan berarah

Trumpet interchange

• The trumpet is the most traditional way of grade-separating a three way junction

• This is your basic free-flowing way to end one road on another.

• It is the sister of the cloverleaf, as both hail from the same period of early grade separation in the 1920s, and as such are heavy on land use and light on construction work - both use only one bridge.

Advantages Trumpet interchange• Low construction costs for bridges/underpasses.• On tolled roads (such as the M6 Toll, where numerous

trumpets are found) the trumpet is a cost-effective way of getting all traffic in one place for toll booths.

Disadvantages Trumpet interchange• Disorienting to navigate for those driving in the direction that

uses the loop.• Expensive to build in places with high land values, and leaves

a redundant patch of land within the loop.• Scaling down the interchange often results in a more

dangerous interchange - the M6 at Stoke frequently suffers congestion from articulated lorries that have tipped over.

Trumpet interchanges 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.

These interchanges are useful for highways as well as toll roads, as they concentrate all entering and exiting traffic into a single stretch of roadway, where toll booths can be installed. A double-trumpet interchange version can be found where a toll road meets another toll road or a free highway.Trumpet interchanges are named as such due to their resemblance to trumpets. The bell of a trumpet can be seen where the terminating highway begins to interchange with the continuous highway, and the resemblance to the tubing is seen along the connecting loop ramps.

Diamond interchange

• A diamond interchange is a common type of road junction, used where a freeway crosses a minor road.

• The freeway itself is grade-separated from the minor road, one crossing the other over a bridge.

• Approaching the interchange from either direction, an off-ramp diverges only slightly from the freeway and runs directly across the minor road, becoming an on-ramp that returns to the freeway in similar fashion.

Diamond interchange

• The diamond interchange uses less space than most types of freeway interchange, and avoids the interweaving traffic flows that occur in interchanges such as the cloverleaf.

• diamond interchanges are most effective in areas where traffic is light and a more expensive interchange type is not needed.

Cloverleaf interchange

• Cloverleaf interchanges, viewed from overhead or on maps, resemble the leaves of a four-leaf clover.

• A cloverleaf interchange is a two-level interchange in which left turns, reverse direction in left-driving regions, are handled by ramp roads (US: ramps, UK: slip roads).

• Typically a cloverleaf is used where a freeway intersects a busy surface street, though many older freeway-freeway interchanges are also cloverleafs.