prior art for controlling traffic
on junctions:
1 1) Rotary Intersection: A.rotary intersection is a specialized from of :intersection ~ laid out for movement of traffic in one direction round a central island. The
I intersections are at the same level but, direct conflict points are changed to
indirect ones which helps the traffic to weave off. However, a rotary intervention
has a certain capacity beyond which it becomes an unviable option (usually
beyond 3000-4000PCUlhr).
2) Signal Controlled: A signal controlled intersection is very common. Traffic
movement from each arm of intersection is allowed to pass one at a time with the
help of stop and go signals. The Signal controlled intersections have their own
limitat~ons especially when the traffic volume is very high. In such cases, long
queues of vehicles are formed at different arms of the intersection causing the
traffic to come to a halt.
3) Trumpet Interchange: This is for a T or Y type of intersection. Figure 1 shows a
Trumpet lnterchange for a three way junction in which, a loop is provided to
grade separate traffic coming from one pliable way and divert it to another pliable
way. Though Trumpet lnterchange offers a conflict-free and stop-free movement
of'traffic between different arms, it occupies a very large area for building a loop
and its construction cost is also very high.
For countries like India where population. density is very high and there is lack of free
space, arrangements such as Trumpet lnterchange is not possible since it requires
large tracts of free land to build a loop and large arcs. Thus, there is a need to
develop a junction with non-stop and conflict free movement of traffic frqm one arm
to another that does not occupy a lot of space and is easier to construct over already
existing road networks.
~ OBJECTIVES OF THE INVENTION:
I In view of the limitations and d~sadvantages of the prior art, an object of the present
inventron is to provide an rmproved form of an interchange on a three way junction
that requires minimum consumption of urban land
Another object of the present invention is to provide an improved interchange on a
three way junction which costs less and is easier to construct.
Yet another object of the present invention is to provide an interchange'which does
not obstruct the speed of traffic stream.
Other objects and advantageous features of the invention will be apparent from the
descriptio'n and claims.
BRIEF DESCRIPTION OF DRAWINGS:
The foregoing and other objects, aspects and advantages of the invention will be
better understood from the following drawings of the invention in which:
FIG.? illustrates a prior art Trumpet lnterchange for a three way junction;
FIG.2 illustrates different types of threeway junctions;
FIG.3 illustrates an embodiment of three way junction according to the present
invention;
FIG 4 illustrates yet another embodiment of three way junction according to the
present invention, and
FIG.5 illustrates yet another embod~ment of three way junction of the present
invention wherein only one lane is affected.
DETAILED DESCRIPTION OF THE INVENTION:
A three way junction is inter-joining of three pliable ways at different angles. Figure 2
shows different types of three way junctions that may be possible. In a T-shape
, junction one pliable way is at an angle of 180' to another and the third one is at 90'
to it. The angle between the three pliable ways differ according to historic
construction, availability of .free land, geographical limitations etc. For a. three' way
junction it is necessary that at least one pliable way is angularly displaced with
respect to any other pliable way.
I Every country has traffic rules to control traffic movement. The most important rule is
that all vehicles moving in one direction have. to move on a particular side and in
particular lanes. The lane of driving direction is called driving lane and the lane of
oncoming traffic is called as oncoming lane. A country either follows Right Hand
Traffic movement or Left Hand Traffic Movement. In Left Hand Traffic:.movement,
drivers have, to keep to their left while, it is vice-versa in case of Right Hand Traffic
movement.
For the ease of explanation and to achieve brevity, the present description explains
the invention only for a Left Hand Traffic movement i.e. the driving lane is on the left
hand side and the oncoming lane is on the right hand side. A person skilled in the art
can easily reckon that the present invention is equally applicable to a Right Hand
Traffic movement by simply mirroring the embodiments explained herein.
Traffic in a particular direction on an arm has degrees of turning at a point of
intersection with other arms. Degrees of turning mean the various directions a
particular vehicle on a pliable way may turn in at the point of intersection with other
roads.
In a three way junction, a vehicle in a driving lane normally has three (3) degrees of
I turning for each arm. For example in Figure 2(d), traffic on arm A can turn left, go
I straight or take a U-turn at the junction. Traffic on arm B can turn right, go straight or
. .
take a U-turn while the one on arm C can go left, right or take a U-turn. Thus, on a
three way junction, traffic has three directions to which it can turn.
When traffic in drlving lane of arm A w~shes to turn right, it has to cross the median
(Ilne dividing driving lane and oncomlng lane) and come into confl~ct with the
oncoming traffic on the oncoming lane from arm B and then it has to avoid conflict
with the traffic turning right from arm C. What if there is no oncoming traffic from arm ~ B and no right turning traffic from arm C at the point of turning of traffic from arm A? ~ A vehicle can then turn right from arm A without stopping. The present invention is ~ . directed to achieve such a .conflict free management of traffic by removing the
aforesaid conflict points.
Figure 3 illustrates an embodiment of the. present invention. According to said
embodiment, a three way junction is provided comprising three pliable ways A, B and
C having lanes al, an, bl, b2 and cl, c2, respectively. Out of these lanes, al, bl and cl
are driving lanes (for Left hand traffic) when considered from each arm while an, b2
and c2 are oncoming lanes for each arm.
The traffic in lane a; can go.straight, take a right turn to arm C or take a U-turn at this
junction. According to the present embodiment of.the invention, lane al is further split
into two imaginary or real lanes all and a12. The traffic meant to go straight remains
on lane all and goes straight to lane b2.
. ' . The traffic meantto turn right takes lane a12. Lane a12 has a separator (GA) to dive'rt
traffic on lane a12 towards arm C so that traffic from lane a12 goes to any of the lanes
of arm C. The traffic from lane a12 may also be shifted to another lane b' just
. adjacent to lane bl and travel in this lane for a short distance before turning right on
arm C..
'In this embodiment, the traffic coming from lane bl .can pass without conflict from
under the Separator (GA) straight to lane a2, which is its right lane as per Left Hand
Traffic: A person skilled in the art can easily reckon that conflict free right turn from
lane a12 to arm C can be made by a grade separator whose level is lower than the
ground level.
Another Separator (Gcs) is provided on lane cl that takes the traffic of arm C over
the junction to arm B. The traffic from arm C can easily turn left on arm A without
conflict and so can traffic from arm B turning left to arm C.
According to another embodiment of the present invention, as illustrated in Figure 4,
the traffic on lane alp, which has to turn to right on arm C, is diverted just to the
oncoming lane a2/bl by way of a Separator (GAA) instead of spanning it ta.arm C or a
third lane. This way the span of the higher or lower level of grade separator is highly
reduced resulting in lower cost of construction. The length of the Separator (GAA) is
reduced because it is required to just shift the traffic to an adjacent lane such that
Left side traffic is diverted to right side meant for oncoming traffic.
Now it becomes necessary to prevent collision of the traffic diverted to the lane a2/bl
with the oncoming traffic as these lanes are meant for oncoming traffic. In order to
prevent this, the traffic on lane bl is diverted to lane b2 at First Diversion (F) before it
reaches the Separator (GAA). After diversion it further reaches lane a12 and from
there it is diverted back to the oncoming lane a2/bl from the Separator (GAA).
In case the traffic from alp is diverted right to arm C from the high level of Separator
(GAA), the oncoming traffic is diverted back to its original/oncoming lane from the
ground level of the Separator (GAA) and vice-versa.
In another embodiment illustrated in Figure 5, a Separator (Gc) is provided on arm C.
Similar. to the earlier embodiment mentioned hereinbefore, traffic on driving lane cl is
shifted to the adjacent lane c2 by one level of the Separator (Gc) and from there it
turns right to arm B on lane b2.
The traffic from lane al turns right to lane cl on arm C instead of the normal way of
turning to lane c2 for Left Hand Traffic. This is so because the traffic moving on
driving lane cl has already been shifted to lane c2 and it would collide with the traffic
coming from arm A lest said traffic is brought on lane cl of arm C. ~he~trafffircom
arm A is further shifted to the right lane i.e. c2 on arm C from a different level of
Separator (Gc).
The traffic moving on arm B passes to arm A through the junction without stopping
by way of Separator (GBA). AS in earlier embodiments, the left turns for traffic on
each arm is already free similar to U-turns.
I
i
Separators mentioned in the description can be of various kinds. A Separator can be
a Grade Separator wherein traffic in one direction is first shlfted to a level different
I from the ground level and then diverted. The traffic moving in another direction can
I either'be made to pass on the ground level or on a second level different from the 1 . first level from where traffic in the other direction is earlier diverted. . "
I Another separator can be a rotary separator.
While the invention has been particularly shown and described with reference to
exemplary embodiments thereof, the invention is not limited to these embodiments. It
will be understood by those of ordinary skill in the art' that various changes in form
and details may be made therein without departing from the spirit and scope of the
invention as defined by the following claims.

We Claim:
1. A three-way traffic junction comprising:
a first pliable way joining a second and a third pliable way forming a three way
junction;
at least one driving lane (al, bl, cl) on at least one of the pliable ways (A,B,C)
having traffic in one direction;
at least one oncoming traffic lane (a?, b;, c2) on at least one of the pliableways
(A,B,C) having oncoming traffic in a direction opposite to that of the at least one
driving lane;
characterized by a first Separator (GAPG AA,G C) to divert traffic on the at least one
driving !ane (a,,, bl, cl) onto the at least one oncoming traffic lane (a2, b2, c2).
2. The three way junction as claimed in claim 1, wherein the first Separator (GA,
GAA, GC) diverts traffic on the at least one driving lane (al, bl, cl) to a third lane
adjacent to the at least one oncoming traffic lane (a2, b2, c2).
3. The three way junction as claimed in any of the preceding claims, wherein
oncoming'traffic on the at least one oncoming traffic lane freely passes on a
second level of the first Separator (GASG AA,G C).
4. .The three way junction as claimed in.claim 1, further comprising , a fir'st diversion.
(F) to divert oncoming traffic on the at least one oncoming traffic lane (a2, b2, cp)
to the at least one driving lane (al, bl, cl) before it 'reaches the first Separator
5. The three way junction as claimed in claim, 1 and 5, wherein the second level of
the first Separator (GA, GAA, GC) diverts the oncoming traffic moving on the at
least one driving lane (al, bl, cl) after the first diversion (F), back to the at least
one oncoming traffic lane (a2, b2, ~2).
6. The three way junction as claimed in any of the preceding claims, further
comprising a second Separator (GCB,G,Bt~o) allow traffic in at least'one direction
on the at least one of the pliable ways to move to another pliable way"freely over
the junction of the two pliable ways.
7. The three way junction as claimed in any of the preceding claims, wherein the
first and second Separator is a grade separator.
8. The three way junction as claimed in any of the preceding claims, wherein the
first and second Separator is a rotary separator.
9. A method for free passage of traffic on a three-way junction comprising:
shifting traffic moving in at least one lane onone'side of the median to at least
one lane on the other side of median meant for oncoming traffic;
further diverting the diverted traffic on the changed lane of the first pliable way to
a second pliable way; and
separating traffic in at least one direct~ono n at least one of the pliable ways to
move it to another pl~ablew ay freely over the junction of the pliable ways
10. A method for free passage of traffic on a three-way junction comprising:
inter-changing lanes of traffic moving in one direction and traffic moving in the
. . oncoming/opposite direction of a first pliable way;
diverting traffic on at least one interchanged lane of the first pliable way to a
second pliable way;
diverting traffic on at least one interchanged lane of the first pliable way back to . .
the lane on which said traffic was prior to interchange; and
. .
. .
separating, traffic in at least one direction on at .least one of the pliable ways to
move freely over the junction of the pliable ways.