General

Owned by Isabelle Avery (Unlicensed)
Last updated: Nov 11, 2022 by Guy Avery
9 min read

Introduction

This page covers the general details used for all highways rules. Depending on the rule type, certain settings may not be available. Be aware that the rule editor is very flexible and allows you to configure many different rules. You should give thought to how these rules are reported to external systems. The primary mechanism for categorising rules is by using the Rule Sub-Type setting. This ensures external systems will always understand what type of alarm is being raised regardless of how many different rule configurations are used.

Contents

General Settings

Name: Create concise yet distinctive names for rules. In situations where numerous rules are listed, it will make it much easier to locate the required one.

Description: The text entered here will become your primary method of identification for the rule within the list. For area movement rules in particular, it can be advantageous to include the name of the monitored area within the rule description for easy identification. 

User ID: A unique user identification.

Enabled: Select this to make the rule active and deselect to deactivate the rule. This is a useful way to quickly deactivate rules that are not needed temporarily.

Sub Type: Optionally allows you to define a particular alarm category for reporting to external systems. Certain rules share the same configuration therefore use this category to uniquely identify each alarm type:  

Person: Person on the carriageway alarm.

Stopped: Stopped vehicle alarm (SVD).

Slow: Slow moving vehicle alarm.

Debris: Debris alarm (debris detected in the highway).

Reversing: Reversing / wrong way driving alarm.

Queue: Queue alarm - one or more sections are in queue.

ERA: ERA alarm - vehicle has been detected stationary in an ERA.

Enforcement: This is an experimental feature used for enforcement detection such as close following ("tail gating")

Default: Custom alarm.

Suppressed Rules: A list of rules to suppress if this rule is triggered. This logic works on a section-by-section basis, so if this rule is triggered in section 2 and you suppressed another rule, then that rule will not be triggered in section 2 until the alarm for this rule has cleared.

Note that the suppressed rule logic relies on the order of rule activation. If the rule doing the suppressing is not triggered first, then it can’t fully suppress the other rules. It will suppress the other rules once activated, but this could be after an alarm has already been raised by an unwanted rule. This problem can be mitigated by using the break count to control the order in which rules are triggered, if they are likely to raised concurrently.

Show Area in Alarm:  When selected, the area or section in which the rule has been broken will be highlighted on the carriageway in the main display.

Track Filter Settings

These filter settings are used to identify tracks that the rule should process and consider as potential triggers for raising an alarm.

All filters should be considered as using AND Boolean logic - so if configured all filters must be true for a track to considered by this rule.

Required Travel (m): The distance required for the track to have travelled before the rule is applied. 

Requited Travel Direction: This is used in conjunction with Required Travel. When you specify that a car must have travelled for a specific distance, you can also specify in which direction.

Any: You do not care about the direction, only the distance travelled

Forward: The vehicle must have travelled for the specified distance in the correct direction

Reverse: The vehicle must have travelled for the specified distance in the wrong direction

Channel Id: This is used to filter the tracks from a specific channel for this rule. For example, you may only want to look at tracks coming through the debris channel - in which case you would set the Id to 32768. This has the advantage of identifying the source of tracks before they are classified. Using a value of 0 means any channel i.e., no filter.

Angle Variation: The angle either side of the direction of travel to look for other tracks.

Track Length Type: Select the way in which the track length is measured.

Diagonal: This is the hypotenuse of the target, using the azimuth and range measurements to calculate it.

Range: The measurement from the radar in a line away from the radar.

Azimuth: This is a measurement of the target at right angles to the radar.

Use Time: Select this this to monitor with a time gap.

Allowed Time (s): The time gap below which a vehicle is considered to be close following.

Allowed Distance: The maximum distance to look for other tracks.

Speed: Applies the rule only to tracks matching the specific speed.

Is Smaller Than (<)

Is Smaller Than Or Equal To (≤)

Is Greater Than (>)

Is Greater Than Or Equal To (≥)

Is Equal To (=)

Is Different To (≠)

Is Between (><)

Is Outside (<>)

Use Direction Filtering: This applies the rule to tracks travelling in only one direction.

Direction Source: The lane which has the desired direction of travel. 

Direction Filter (°): The margin in error for direction in degrees (e.g., a value of 30 would mean both a -30° and +30° deviation from the normal is applied, therefore a total deviation range of 60°).

Adaptive Speed Filtering Settings

This feature can be used instead of fixed speed filter values to identify vehicles which are deviating from the average speed of traffic in each section. The adaptive speed check looks at the average speed of the traffic in a section and works out if any track in the same section is going slower by the specified Speed Deviation (%). In addition, it checks the number of vehicles in each section and if this value falls below the Min Track Count then the average speed is considered to be unreliable and the normal fixed speed filter values are used instead.

Use Adaptive Speed Filter: Enables or disables the adaptive speed check:

Speed Deviation - The speed difference between a vehicle and the section’s mean speed expressed as a %. Vehicles that are moving slower than the speed deviation will be considered by this rule.

Min Track Count - The min number of vehicles that must be present in a section for the adaptive speed control to be active. If the count drops below this figure, then the adaptive check is ignored and the fixed speed filter values are used instead.

Property Filter Settings

A property filter is used to analyse a specific property on each track. This could be anything from track size to direction. These filters help narrow down the alarm criteria so they are only raised when the conditions are correct. For example, you may want to only alarm if you detect a stopped vehicle that is above a certain size. This can help distinguish between debris and small vehicles.

There are 3 property filters, therefore each filter can be configured to look for a different property value.

All property filters are optional but once more than one is enabled, then like all other track filters on the rule, they will operate using the AND Boolean logic - so all conditions must be true for the track to be considered by this rule

Property Name: Defines the numeric property that will be monitored by the rule. In each case, the Property Value 1 entry (and in some cases Property Value 2) are where you enter the corresponding value(s) to be ruled against for the chosen property.

None: No specific numeric property is monitored - this is the default and cannot be used when configuring a property filter

Azimuth Size (m): Monitors the area of a target measured across the radar scan's perimeter, along the azimuth.

Coast Ratio: This is the ratio of coasted tracks to real sightings - so if the target has been seen 20 times and has coasted 5 times the coast ratio would be 0.25. Coasting is when the tracker loses sight of a track and so instead estimates where the track should be based on previous sightings. 

Course: Monitors the pathway of a target. 

Weight: Monitors the total number of cells that make up the target.

Bearing (degs): Monitors the direction of travel of a target in degrees clockwise from the radar.

Area Size (m²): The area size of a target as viewed by the radar sensor.

False Alarm Probability: This is the FA probability allocated to each sighting following the Machine Learning False Alarm analysis algorithm.

Adjusted Strength: Monitors the sum of the signal strength for each cell which makes up the target, taking into account cell beamwidth increase over range

Range (m): Monitors the track's distance from the radar. 

Travelled: This is the distance the target has travelled relative to carriageway. A positive value indicates movement in the correct direction of the carriageway and a negative value means the vehicle is travelling in the wrong direction.

Average Speed: This is average speed since the target was first seen.

Strength: Monitors the radar signal strength for a target.

Speed: Monitors the speed of travel of a target.

Seen: This is the number of times the target has been seen by the radar based on the rotation / update frequency of the radar.

Avg Area Size (m²): The average area size of a target as viewed by the radar sensor over the period of time that it has been tracked.

Max Area Size (m²): The maximum area size of a target as viewed by the radar sensor over the period of time that it has been tracked.

Adjusted Weight: Monitors the total number of cells that make up the track, taking into account cell beamwidth increase over range.

Area Covered: The maximum dimension of the area covered by the movement of the target. For example, if the target is moving down a road, then this value would be quite large. If the target is stationary or loitering, then we would expect this value to be small.

Breaking Condition: Determines the main argument used by the rule in combination with the Property Name and Property Value(s) options. Breaking Condition options for area movement rules are either Is Inside or Is Outside (the area). Breaking Condition options for numeric rules include Is Smaller Than, Is Equal To, Is Between, Is Outside etc. (the latter two options require two Property Values to form a range). 

Is Smaller Than (<)

Is Smaller Than Or Equal To (≤)

Is Greater Than (>)

Is Greater Than Or Equal To (≥)

Is Equal To (=)

Is Different To (≠)

Is Between (><)

Is Outside (<>)

Property Value: Defines the numeric quantity (or quantities) that is/are related to the chosen Property Name and Breaking Condition. For instance, if the chosen Property Name is Speed, then the Property Value must contain the value of the speed in miles per hour. Where the Breaking Condition is set to either Is Between or Is Outside, there will be two Property Values in order to form a range.

Alarm Settings

Severity: Defines how a target should be marked when it breaks a rule. Such markings allow targets which present a warning or threat to be easily differentiated from friendly and unclassified targets.

Unknown

Friend

Warning

Threat

Action: Defines the action that should be taken when a rule is broken.

None: Used primarily for rules that will be used to form a compound rule.

Follow: Instruct the nearest camera to follow the target.

Alarm: Display a message, logs an alarm and sound an audio alert.

Alarm and Follow: Display a message, logs an alarm, sound an audio alert and instructs the most appropriate camera to follow the target.

Alarm Description: Determines the text that will be presented to the operator (and entered in the activity log) when the rule is broken and an alarm is raised. Note that you can use the follow place holders which will automatically be populated with the relevant data when the alarm is raised. The place holders are as follows:

{CARRIAGEWAY} : Will be replaced with the carriageway name where the incident has occurred.

{CARRIAGEWAYID} : Will be replaced with the carriageway user Id where the incident has occurred.

{SECTION} : Will be replaced with the section name where the incident has occurred.

{SECTIONID} : Will be replaced with the section user Id where the incident has occurred.

{LANE} : Will be replaced with the lane name where the incident has occurred.

{LANEID} : Will be replaced with the lane user Id where the incident has occurred.

{RULEID} : Will be replaced with the user Id of the rule which has generated the alarm.

{CLASSIFICATION} : Will be replaced with the classification description of the track causing the alarm.

Alarm Priority:  Allows you to optionally apply a ‘weighting’ to any rules that invoke an Action using the priority values below. This value can be used elsewhere in the system to prioritise actions when there are multiple concurrent alarms. For example deciding which alarm to follow with a camera.

Lowest

Low

Medium

High

Highest

Audible Alarm: Select this for the alarm to be audible if breaking the rule results an alarm action. 

Alarm File: Choose a specific mp3, wav, mp4, wmv file to sound if an audible alarm is required. This will overwrite the default alarm sound for this specific rule.

Per Track Alarms: This will give an alarm for each track

Alarm Generation: Select this to generate alarms for All Sections or Head of Queue.

Head of Queue:

Queueing Sections: The minimum number of continuous queueing sections.

Non-Queueing Sections: The minimum number of continuous non-queueing sections after a queueing section.

Safety is everything.