sj-5112 grade separation intersections

8/7/2019 SJ-5112 Grade Separation Intersections

http://slidepdf.com/reader/full/sj-5112-grade-separation-intersections 1/24

SJ-5112

Perancangan Geometrik Jalan

Grade Separation and InterchangeGrade Separation and Interchange

Introduction

The first interchange was constructed in

Woodbride, NJ in 1928

It was a Cloverleaf

AASHTO introduced the various forms of

interchange in A Policy on Geometric Design of

Highways and Streets



Interchange Categories

System Interchange:

o Interconnects two freeways

oHaving free-flowing ramps with no intersections

Service Interchange:

o Connecting a freeways with a surface streets

oHaving one or more ramp intersections with crosroad

Basic Interchange Forms(AASHTO Standards)



Basic Interchange Forms

T and Y interchanges (three-leg interchanges);


Diamond interchanges;




Partial cloverleaf (ParClo) interchanges;

Cloverleaf interchanges;


Directional interchanges (with or without loop

ramps)



T and Y Interchanges

T and Y Interchanges

They can be all directional

Or with one or two ramps

The configuration with one loop referred ro as

‘trumpet’ form



Trumpet Forms

A

B

Which one is better?

B: the loop ramp is beyond the crossroad

for the driver approaching the intersection

A: the loop ramp is advance the crossroad

for the driver approaching the intersection

Trumpet Forms

D

CWhich one is better?



Two-Loops Forms

E

F

Capacity of 1,200 ∼ 1,400 v/h

Capacity of 1,500 ∼ 1,800 v/h

Two-Loops Forms

Ancol



Diamond Interchanges

Diamond Interchanges

Rural diamond;

Compressed diamond;

Tight-urban diamond;

Single-point diamond;

Three-point diamond;

Roundabout diamond;

Three-level diamond



Diamond Interchange

Florida

Rural Diamond

o Can be found in rural area

o Service interchange

o Typically, the rural road passes over the freeway

o Problematic at the crossroad



Compressed Diamond

o Common form in suburban areas

Tight-Urban Diamond Interchange



Tight-Urban Diamond Interchange

Single-Point Diamond Interchange



Single-Point Diamond Interchange

Three-Point Diamond Interchange

o Having four ramps 2-exit and 2-entrance

o Similar to other diamond interchange

o Having three intersections instead two or one



Split Diamond Interchange

Roundabout Diamond Interchange



Three-Level Diamond Interchange

Cloverleaf Interchanges



Cloverleaf and Partial Cloverleaf

Most of them are system interchange

The main feature of cloverleaf and partial

cloverleaf interchange is to accommodate all or

some left-turning (right-turning, case of

Indonesia) movement by installing loop rampsloop ramps

An interchange with a full complement of loopramps is designated as a cloverleaf

Cloverleaf Interchange

There is only one basic form of cloverleaf

interchange with four loop ramps

Cloverleaf were common interchange prior to

1970s as system interchange

However,

o Experience gained relatively low capacity due to four

weaving sections between loop ramps and high accident

rates



SemangiSemangi, Jakarta, Jakarta

Cloverleaf Interchange, continue…

In the urban areas, right-of-way of cloverleaf

becomes extremely expensive

oNegative operational experience was gained

• e.g. reducing speed and incidents in ramps

oNowadays, other forms were operationally better and

less right-of-way were needed

o Some old cloverleaf s were reconstructed with auxiliary

lane to separate the weaving traffic



ParClo Btypical movements

N-S: Road

W-E: Freeway

N

E

S

W

W N

W S

E N

E S

NW

SW

N E

S E

Comparison of Service Interchangein urban area*

* Based on hundreds of interchange selection and design studies in more than 20 urban areas



Directional Interchanges

Directional Interchanges

Being used at the intersection of two freeways in

both rural and urban

System interchanges with free flow for all turning

and through traffic movements

They can be all directional or directional with

loops



Typical Traffic Movements

(Full) Directional Interchange



Circle Interchange, Chicago

Semi Directional Ramp

Albany, US



end of lectures

sj-5112 grade separation intersections

Documents