Urban Traffic Control

Clear as mud traffic signals !!!

2012-01-27T09:49:00.000+11:00

This is an example of maybe how not to put up traffic signals, however, given its location and application (road/peds/trams) it may be inevitable.

Austroads Home Page

2010-10-15T09:38:00.000+11:00

Austroads Home Page

This is a link to the website of the Association of Australian Traffic and Road Authorities. This body discuss standards about all aspects of road construction, traffic management, signalling system and other related items.

This body also conducts research for and on behalf of the road authorities that is used to formulate policies used by these authorities.

This is an area of interest for all traffic signal control systems as far as the Australian context is concerned.

SCATS - Sydney Co-ordinated Adaptive Traffic System

2010-10-06T15:44:00.000+11:00

SCATS is an Australian developed adaptive Urban Traffic Control system that has been in use since the late 1970's in Sydney and has now been deployed in over 70 cities around the world.

Recognised for its adaptive nature to make sure that traffic is moved in the most efficient manner possible given the constraint of limited capacity road in highly urbanised cities such as Sydney, Australia.

SCATS - Sydney Co-ordinated Adaptive Traffic System

The link to the SCATS product site gives the reader a background in how it works and how it integrates with Public Transport systems with dedicated bus prioritisation corridors.

SCATS developed its "view" of traffic by gathering vehicle count data in real time and would form a view where the majority of "demand" for time would be. SCATS then executes changes to each intersection's "cycle time" to ensure that a little more time is given to roads where the vehicle count is consistently greatest until it is reduced to more normal levels.

The process of changing an intersection's cycle time is the "adaptive" part of Urban Traffic Control and essentially works to clear the traffic in a particular direction.

When SCATS was first deployed it made use of dedicated "leased lines" also known as "permanently attached private lines (PAPL), and in fact, the SCATS monitoring system was deployed by having a Central Manager at the top of the computing model and one or more Regional Computers (RC). The Regional Computer has the responsibility of communicating with each intersection's Traffic Signal Controller.

A Traffic Signal Controller is the traffic signalling device that "counts" the number of vehicles on the roads, as well as "driving" the traffic lights.

Having a hierarchical model means that the SCATS "monitoring" network has several layers of redundancy, as the Central Manager forms a high level view of the "whole city's traffic flows". The Regional Computer monitoring a local region and is the primary engine changing the cycle time in accordance with special queuing theory algorithms so it forms a more "regional view" of traffic flow.

So in essence the data flow is: Traffic Signal Controller -> Regional Computer -> Central Manager.

What is important here is that in the event that any one of these communication connections is broken, there is no major effect on the continuation of traffic control. Once communications is re-established then the SCATS system exercises its control over the local road intersection by commanding and changing the cycle times to achieve coordination between adjacent intersections.

This also means SCATS has an in-built disaster recovery mechanism because the Regional Computers can be physically spread around the city, so in the event of the Central Manager computer being unavailable, the Regional Computer will continue to exercise effective coordination for its given regional road network.

SCATS is distributed by ATC in Sydney Australia and has experts in the implementation and optimisation of SCATS systems.

To Tame Traffic, Go With The Flow - Science News

2010-10-05T12:56:00.000+11:00

To Tame Traffic, Go With The Flow - Science News

This article published in ScienceNews goes a long way to suggesting that the method of flow control used by the SCATS Urban Traffic Control system which live by the mantra:

"The new approach makes traffic lights go with the flow, rather than enslaving drivers to the tyranny of timed signals. "

and this seems to give the best results given the variability of demand and the "ebb and flow" of traffic in different directions in the morning and afternoon peaks which is exactly how the SCATS Urban Traffic Control system works.

ATC distributes SCATS and has long championed this type of adaptive traffic management around the world when cities have wanted to address city traffic congestion.

Info on the SCATS system is available on ATC's SCATS product website and the SCATS website.

Victoria | Transport Committee Road Safety Advancements

2010-09-21T17:11:00.000+10:00

Victoria | Transport Committee

This link is to a series of presentations on Road Safety Advancements by VicRoads and was facilitated by the victorian chapter of Engineers Australia

It is an excellent snapshot of where multiple authorities including traffic, police, forensic, rail and infrastructure departments have collaborated to reducing the road and pedestrian tolls with some encouraging results.

What is Urban Traffic Control?

2010-08-13T00:05:00.000+10:00

Urban Traffic Controlis the science and engineering behind adaptively moving traffic in the most efficient manner based on the degree of saturation (the amount of time vehicles spend on a lane traffic loop).

There are various systems such as SCATS (www.scats.com.au) and SCOOT, ITACA and more.

One of the more advanced and used such UTC systems is that developed by the Roads and Traffic Authority of NSW in Sydney, Australia.

The system uses advanced queuing theory alogorithms to adapt in real time the signal phase times to ensure that the most amount of road traffic is moved without stifling side or lesser used road traffic.

The SCATS system receives road traffic vehicle counts from Traffic Signal Controllers located at each intersection and then it sends the most optimal times the phases should be running.

In this way, coordination across many intersections may be achieved resulting in smoother traffic flow in highly urban city centres.