Greatly improved traffic flows by self-controlling traffic lights
Self-regulation, Traffic, Public transportation, Pedestrians, Cyclists, Construction sites, Accidents, Energy efficiency, Environmental protection,
Managing complexity, Bottom-up control, Production and logistics
Modern intersections are controlled in
a largely centralized and predetermined cyclic manner with trafficadaptive green wave control systems.
Shortcomings of the current system
are the predominant focus on the
main roads and restrictions like a
common cycle time on all intersections and the periodic service of road
Traffic flows can be greatly improved
by moving away from imposing such
control schemes and by letting the
traffic streams control the traffic lights
(decentralized bottom-up control).
Figure 1: Self-controlling
traffic lights can be easily
implemented. Camera‘s
(1) and (2) monitor the
traffic flow, the controller
(3) self-regulates the
traffic flows, based on a
new priorization principle
and switches the traffic
lights (4) on and off in a
flexible and adaptive
The new technology is performing
traffic control with a wholistic approach. The control concept does
local optimization with maximum flexibility, taking care of all traffic streams,
incl. public transportation, cyclists,
pedestrians and side streets. Impressive improvements can be achieved
by traffic lights going on and off in a
self-controlled way (Fig. 1), not based
on periodic patterns but based on
priorities assigned to arriving vehicle
platoons. This may seem chaotic, but
it has been proven to be highly effective. The system automatically adopts
to variations in turning flows, unexpected situations like accidents or
temporary road works. The traffic
lights are controlled by the traffic
streams. With this self-controlled system, traffic flows can be greatly improved as was shown in an extensive
pilot study in Dresden (Germany).
Results showed significant improvements (less delay) compared to stateof-the-art green wave control: 56%
improvement for trams and busses,
36% improvement for pedestrians
and cyclists and 9% improvement for
cars and trucks. When public
transport is less prioritized, vehicle
flows can be improved by about 30%.
Patent granted (USA, JP, DE, AT,
CH, FR, GB, IT, LU, PL and TR)
Patent pending (CN, IN)
Features & Benefits
Significant reduction of the average
travel times and of fuel consumption and CO2 emissions
Flexible traffic optimization system
with superior performance
Cost effective implementation:
existing traffic control systems can
easily be upgraded with the respective detectors and software
System can easily be adopted to
local situations in different countries
Field of Application
Traffic control in cities
Regulation of competing processes
or flows such as production systems and logistics
Complex project management and
administrative processes
Ref. No. T-07-061
ETH Zurich
ETH transfer
Zurich, Switzerland
Patent Status
+41 44 632 23 82
[email protected]
Lämmer, S, Helbing, D. J. Stat.
Mech.: Self-control of traffic lights
and vehicle flows in urban road
networks, P04019 (2008)

Greatly improved traffic flows by self