




The TLSI takes the conventional intersection and its 4 signals into a 2level intersection and separate the signals
into 2phase signals for each of the top and bottom roads of the intersection.
 Since the traffic signals are processed independently for the
top and the bottom roads of the intersection, the duration of the green
light is more than doubled.
 The top and bottom signal systems function independently and
are not affected by each other.
 Application of ITS (Intelligent Transport System) would result
in better synergy than the conventional intersection. 







 The conventional intersection utilizes the following combination
of signals:




Case
1 : Dual left turn signals, and dual straight
through signals Case 2 : Vehicles entering the
intersection from all four directions utilize straight through and
left turn signals. Case 3 : Combination of Case
1 and Case 2. 















 Let¡¯s take a look at the road utilized by vehicles entering
intersection from east and west versus north and south in a typical
conventional intersection. 







 Vehicles can choose from four directions of travel, namely, left
turn, straight through, right turn and Uturn.





marks the part of the road utilized by vehicles entering the intersection
from east or west. 




marks the part of the road utilized by vehicles entering the intersection
from north or south. 



 Developed by Roadnext, the TLSI puts
Diagram 1 on top of Diagram 2 to make a twolevel intersection
from a conventional intersection. 







 As such TLSI utilizes different sets of signal system for the top and the bottom part of the intersection.
In other words, northsouth traffic is controlled with one signal system on the bottom parts of the intersection, while eastwest traffic is controlled with another signal system on the top part of the intersection. 



 The number of signal systems used is two for the top and two
for the bottom part of the intersection. 



 As such, the top part and the bottom part of the intersection
are of the same structure, and the directions of travel are identical
to the conventional intersection. (Left turns are made from the
left lane, and right turns are made from the right lane.) 



 This is partially identical to the top part of SPUI (SinglePoint
Urban Interchange). For more details, please
click on Overview II. 


