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Introduction

This section explains the ClearWay™ Rules, their purpose and configuration.

Rules form the core intelligence of the system, permitting automatic decisions to be made based upon observed behaviour in the field. One of the great strengths of the ClearWay™ application is its ability to assist the operator by making decisions in response to sensed target movements. As a result, a continual watch can be placed upon all areas of interest, with the operator being alerted (or other actions initiated) only when particular criteria are met. The key factor in enabling such intelligent automated behaviour is the use of rules.

Within ClearWay™ the rules are designed to detect incidents on the highway, however the rule configuration is very flexible and allows the system to be adapted for different types of highways and traffic.

Contents

Carriageway Wizard Rules  

When adding a carriageway: Adding Carriageways the Carriageway Wizard offers the opportunity to create the carriageway complete with a selection of default rules. The default rules created are:

Person Rule

Slow Vehicle Rule

Reversing Vehicle Rule

Queue Rule

Debris Rule

Stopped Vehicle Rule

Wizard Configuration

You can select which of these rules is created and you can also change the key settings as part of the wizard process.

The first page of the wizard offers the selection of rules, note that all rules are selected by default:

The second page gives you the ability to adjust the key parameters of each rule. Note that each rule has its own page:

Typically the default parameters will work in nearly all situations, so careful thought should be given when changing the rule settings and we recommend that any rule variations are tested to ensure the results are as expected.

Creating a New Rule

To manually create a new rule without using the wizard:

  1. In the Configure Rules window, select New.

  2. Select Rule Type:

    Speed Rule: Section speed rule - looks for one or more vehicles moving slowly in a section.

    Queue Rule: Queue rule - alarms when a section has gone into queue.

    Classification Rule: Section classification rule - looks for one or more vehicles with the specified classification, can include other filters such as speed etc.

    Reversing Rule: Section speed rule but designed specifically to look for vehicles going in the wrong direction at a specified speed.

    Track Speed Rule: Track speed rules are used to analyse each track in turn. Like all other rules, this will raise an alarm for a section, but the rule will look at each track individually to identify if it has broken the rule.

  3. Select Create Rule. The new rule is now configurable as above.

Speed, Queue, Classification and Reversing Rules are Section Rules. This means that, by default, each section is examined at regular intervals for evidence of of one or more tracks breaking the rule.

A Track Speed Rule is a Track Rule. This means that each track is individually examined as to whether it is breaking the rule.

Speed Rules and Track Speed Rules are different. A Speed Rule checks multiple tracks in each section over time against speed parameters; i.e. looking for common behaviour in traffic, whereas a Track Speed Rule checks individual tracks against speed parameters. For an individual track to trigger an alarm we must be satisfied that the track is real and the rule is definitely broken, so a high break count is set. Therefore, a Track Speed Rule is more suited to a Stopped Vehicle Rule where we are looking at the behaviour of individual tracks.

Configuring a Rule

To configure a new rule, please refer to the documentation concerning each rule section:

Testing a Rule

Rules can easily be tested to ensure that the correct alarms is triggered when a rule is broken. In the Configure Rules window, you can generate a test alarm from any of the existing rules.

  1. Select the rule you wish to test. Then, select Test. 

  2. The Rule Test window will appear. Choose the length of the delay, the Start Section, End Section and Lane you wish the alarm to be tested in, then select OK.

  3. This will automatically generate an alarm for each section that you have chosen in turn, with a pause of the specified delay time between each alarm. By default the delay is 1 second.

The alarm notifications will be visible (and if enabled, audible) and the relevant section will change colour to reflect the alarm severity, assuming this option was selected in the rule configuration.

Related Information

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Safety is everything.