Intelligent Roadway Information System

Alerts and Warnings

IRIS can poll weather and other emergency alerts from feeds using the Common Alerting Protocol CAP, and post messages on Dynamic Message Signs (DMS).

When configured properly, the system will perform the following functions:

  1. Poll a feed and parse the CAP alerts.
  2. Process alerts with configured event types.
  3. Identify DMS within the alert area.
  4. Post messages to signs.
  5. Update messages on signs when alerts become active, expire, or when changes are issued by the alerting authority.
  6. Remove messages from signs after an alert expires.

The system can operate in either automatic mode, where alert messages are posted with no human interaction, or in approval mode, where an operator must confirm messages before they are posted or updated. The alert system is managed from the "Alert" tab and other dialogs and system attributes.


In the US, the Integrated Public Alert and Warning System IPAWS collects and distributes a wide variety of public alerts and warnings that originate from over 1,500 alerting authorities. The most common alerts are weather related, and are issued by the National Weather Service.

Obtaining Access

The IPAWS Open Platform for Emergency Networks (IPAWS-OPEN) is operated by the Federal Emergency Management Agency (FEMA). Obtaining access requires approval by the agency and a signed Memorandum of Understanding (MOU). Each organization running IRIS must obtain their own authorization and may not share it with other organizations.

The authorization process can be initiated by sending a request to IPAWS@FEMA.DHS.GOV, after which the IPAWS Program Office will send the necessary forms for completion. After the completed forms have been returned, an MOU will be provided for signature. Once the signed MOU has been executed, the URL required to access IPAWS-OPEN will be provided.

CAP Feed

A CAP feed is configured via a comm link. The comm config must use the CAP protocol, with a timeout of 8 seconds and idle disconnect time of 10 seconds. A polling period of 60 seconds is recommended, but you may use longer periods if desired.

The comm link must contain the URL for a valid CAP feed. For IPAWS-OPEN, the path ends with recent/, followed by a date/time stamp. IRIS will add the date/time to each request if the provided URL ends with /. The URL must also contain a query string with a your pin (e.g. ?pin=ABC123).

A CAP comm link requires a controller in ACTIVE condition to operate. With polling enabled and the controller in active condition, IRIS will poll the URL provided at the configured polling period. Each polling cycle will check for new or updated alerts, parse and process them to determine if they are relevant and, if appropriate, create messages for deployment. This processing is controlled by alert configurations.

Forecast Zones

Alerts from the National Weather Service use special codes to define GIS forecast zones. This information can be obtained in shapefile format from NWS and loaded into the tms database.

To load geometry data, download the latest Public Forecast Zones shapefile to the IRIS server and unzip it. To import the file, execute the following command on the server:

shp2pgsql -G <nws_shapefile>.shp cap.nws_zones | psql tms

NOTE: Alert areas may change (NWS updates the file roughly every six months), so it is important to keep them updated. Administrators should keep records of when this information was last updated and maintain the latest information in the database.

Alert Configuration

As only a subset of alerts will typically be of interest to a particular organization, IRIS provides a detailed framework for configuring the response to each alert.

Select the View ➔ Alerts ➔ Alert Configurations menu item.

This dialog displays the alert configurations and allows creating new ones. A configuration links specific alert properties with a DMS hashtag and one or more alert messages.

To create a new alert configuration, press the Create button. After the new configuration appears in the list, select it and assign the desired properties to match. Also, select a DMS hashtag and create one or more messages.

Event Types

Each alert will contain an event field to describe the subject of the alert. Some of the more common events that may be observed include:


Alerts can be selected in a configuration based on four parameters: responseType, urgency, severity and certainty. An alert will only be selected if all four of these parameters match the configuration.

Auto Deploy

An alert configuration can be flagged to automatically deploy when it is matched with an incoming alert. In this case, operator approval is not required, and signs will be deployed with no intervention.

Hours Before and Hours After

Additional messages may be posted BEFORE an alert has started or AFTER it has ended. The duration of these periods is controlled via the "Hours Before" and "Hours After" times, respectively. A value of 0 will disable that period for the configuration.

DMS Hashtags

Signs that are eligible for inclusion in an alert configuration should be tagged with a specific DMS hashtag. When an alert matches the configuration, only signs with that hashtag will be considered when searching the area defined by the alert CAP message.

Signs that are inside the alert area will be automatically used to display messages describing the alert, unless an operator decides to exclude them. If the alert_sign_thresh_auto_meters system attribute is set to a non-zero value, signs within alert_sign_thresh_auto_meters meters of the alert area will also be included.

If the alert_sign_thresh_opt_meters system attribute is set to a non-zero value, signs within the sum of alert_sign_thresh_auto_meters and alert_sign_thresh_opt_meters will be suggested for inclusion in the alert deployment when reviewed in the deployment dialog.

Alert Messages

An alert message defines an alert period and a message pattern. The period can be BEFORE, DURING or AFTER, and selects the time relative to the start and end of the alert. The message pattern will be displayed on signs with a matching restrict hashtag during the associated period.

A message pattern can contain DMS action tags, since alerts are deployed as action plans. Specifically, the time action tag is useful for displaying the the alert start or end time as part of a message.

Operating the System

The system is managed in the Alert tab of the IRIS client. This tab lists all relevant alert deployments (i.e. those with matching configurations and DMS in the alert area) that have been processed by the IRIS server. Alert deployments are grouped into the following styles:

Style Description
Pending Deployment is pending operator approval
Active Alert action plan is scheduled and may be deployed
Cleared Alert is in the past or cleared by an operator
All All recent alert deployments

When an alert deployment is selected from the list, the tab will populate the area below it with information about the alert and the DMS included in the deployment. When an alert is selected, the map will display a polygon showing the alert area, along with the signs that are included in the alert. If the alert area is not visible, you may right click on the alert deployment and click "Zoom to Alert Area" to center the map on the alert area.

The alert tab also functions as the approval/edit dialog. This allows operators to approve alerts for deployment in addition to editing active deployments.

When a new alert is received that is eligible for a message deployment, the IRIS server will process it to determine the signs for inclusion and the message(s) that will be displayed. Each matching alert configuration will add an entry to the alert list, with a corresponding DMS hashtag. If the configuration is not marked "auto deploy", its state will be "Pending".

Operators may adjust the signs that are included in the deployment by checking or unchecking the box next to each DMS in the list. This list is limited to signs in or near the alert area (with proximity determined by the alert_sign_thresh_auto_meters and alert_sign_thresh_opt_meters system attributes). Operators must have the alert_deploy capability to approve or edit alert deployments.

If the alert configuration is flagged as "auto deploy", alert deployments will automatically be sent to signs with no human interaction.

Active alert deployments can edited by selecting the alert in the list and clicking on the "Included" check box next to a DMS.

Operators may also cancel any deployment by clicking the "Cleared" check box. Once cleared, alerts will be found in the "Cleared" style until it is past the the post-alert time. Cleared alerts can be redeployed by unchecking the "Cleared" box.

Attention Panel

The system includes a notification feature to facilitate operation in approval mode and keep operators aware of alert deployments in automatic mode. When the system encounters alerts that are eligible for deployment, IRIS clients will notify users via the flashing yellow "Attention" button in the lower-right corner of the interface. Clicking this button will open a menu containing pending alerts, and selecting one will open the Alert tab and select the corresponding alert.

The "Attention" button will continue to blink until the alert has changed from pending mode.

Testing the System

Because the alert system requires alert CAP messages in order to function, it can be challenging to test. To address this, IRIS provides a testing mechanism that allows testing the system with a mocked-up CAP message. To use this, first a CAP XML message must be crafted with:

To do this, it is best to start with a real CAP message taken from IPAWS-OPEN (e.g. one that is old or targets a different area) and replace the values with ones suitable for testing. This must be done with care to ensure the CAP standard is followed and the message can be parsed.

After a CAP message is created, it can be fed into IRIS in one of two ways.

  1. The file can be hosted on an arbitrary HTTPS server (including the IRIS server itself if HTTPS is supported). IRIS can then be configured with a comm link that points to this file on that server.
  2. The file can be placed in /var/log/iris/cap_test.xml on the IRIS server itself, and the controller of an existing CAP comm link can be put into the TESTING condition.

In either case IRIS will read this file and process the alert as if it were a real alert. Note that in a production environment this may activate real signs, so care must be taken to ensure the testing is done in a controlled manner.