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Introduction
This section explains the ClearWay™ Rules
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, their purpose
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and configuration.
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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.
Rules consist of basic conditions, such as:
- ‘If a target enters this area then sound an alarm’
OR
- ‘If a target is moving faster than 4 meters per second then follow it with a camera’.
Within ClearWay™ you can also combine two or more rules to apply very specific controls to particular regions. In addition to a set of adjustable default rules, you can also create any number of new rules using logical operators and other properties to achieve almost any desired outcome.
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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.
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Contents
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Carriageway Wizard Rules
When
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adding a carriageway: Adding Carriageways the Carriageway Wizard offers the opportunity to create the carriageway complete with a selection of default rules
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.
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The
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Configure Rules
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default rules created are:
Person Rule
Slow Vehicle Rule
Reversing Vehicle Rule
Queue Rule
Debris Rule
Stopped Vehicle Rule
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Each is configurable, and has the ability to be switched on and off, or deleted. To configure the rules:
- Under the Config tab, select the Carriageway in the Entity Tree.
- In the configuration panel, select the ☰ options button next to Actions.
- Select Rules, and a Configure Rules window will appear.
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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:
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The second page gives you the ability to adjust the key parameters of each rule. Note that each rule has its own page:
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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:
In the Configure Rules window, select New.
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Select Rule Type:
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Speed Rule: Section speed rules look for one or more vehicles moving slowly in a section.
Queue Rule
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: Queue rules alarm when a section has gone into queue.
Classification Rule: Section classification rules look 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.
Close Following Rule: This looks for when a vehicle is travelling too closely behind another vehicle. 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.Select Create Rule. The new rule is now configurable as above.
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Speed, Queue, Classification and Reversing Rules are Section Rules. This means that |
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, by default, each section is |
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examined at regular intervals for evidence |
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of of one or more tracks breaking the rule. |
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Track Speed |
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and Close Following Rules are Track Rules. This means that each track is individually examined as to whether it |
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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 |
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more suited to a Stopped Vehicle Rule |
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Advanced
- Advanced:
- Break Allowance (s): alters the number of times that the rule can be broken before the defined Action is triggered. The default value of 1 will trigger an alarm at the first instance. Default: 1s or 1 hit.
- Use Allowance Curve: this option works in conjunction with the Break Allowance. When this option is enabled, the break count is permitted to go down as well as up. The break count will be incremented when a target is breaking the rule and then decremented when it is not. Additionally, you can set the Allowance Increment and Allowance Decrement values so that you can weight the rate at which a target increases and decreases its break count. The alarm will only be activated once the Break Allowance value is reached. This option is useful in situations where you expect targets to momentarily break rules but not to continue doing so and so prevent false alarms. Default: Disabled.
- Allowance Increment (s): (used only when Use Allowance Curve is enabled) Defines the amount by which the break count should be incremented every time a target breaks the rule. Default: 1s or 1 hit.
- Allowance Decrement (s): (used only when Use Allowance Curve is enabled) Defines the amount by which the break count should be decremented every time a target ceases to break the rule. Default: 1s or 1 hit.
- Relay: defines the Id of the relay that should be activated when the rule is broken. Choose ‘0’ to disable. Default: 0.
- Trace Logging: outputs more information about what causes the rule to break. Mainly used for carriageways with more convoluted rules. Default: Disabled.
- Count Coasted Tracks: select this to count coasted tracks towards the break allowance. De-select for them to be ignored. Default: Enabled.
- Classification Filters:
- Classification: optionally dedicate the rule to objects of a particular type as differentiated during the tracking process. When set to Any, the track must be classified but can be any classification. To include every track regardless of classification you must set this to Any and also select Include Unclassified. Default: Any.
- Classification Probability (%): allows you to optionally define a confidence level which must be matched or exceeded for a given track (of the type selected within the Classification option discussed above) before it can be considered within the rule. The use of this option provides an opportunity to filter out potential nuisance alarms. The main probability value is created during the tracking and classification process and is displayed against each entry within the Tracks tab. When this option is set to zero, the requested Classification type will be accepted at any level of probability (as determined by the tracker), rendering this filter inactive. Default: 0%.
- Include Unclassified: select this to include unclassified tracks as rule targets alongside the Classification filter. Default: Enabled.
- Alarm Suppression by Nearby Queue: this option will suppress this rule and alarm if there is a nearby queue. Either on a different carriageway, the same carriageway or both. This option is useful to reduce false alarms in one carriageway when there is heavy or queuing traffic in the other.
- Queue Detection Distance (m): how far to check for queues. This is a straight line distance from the alarm location to the nearest queue. Default: 0 m.
- Queue Source Filter: this is the carriageway filter which specifies on which carriageway to look for queues. Default: Other Carriageways.
Testing a Rule
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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
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is triggered when a rule is broken. In the Configure Rules window,
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you can generate a test alarm from any of the existing rules.
Select the rule you wish to test. Then, select Test.
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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.
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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
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) and the relevant section will change colour to reflect the alarm severity, assuming this option was selected in the rule configuration.
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Video
The following video shows the creation of a new classification rule, testing it using the Test option, and then using a Playback Track to simulate the rule being broken:
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