Overview
Dangerous Slowdowns, also referred to as DSD, is a product feature under the INRIX safety alerts umbrella and is intended to offer advance warning for where back-of-queue slowdowns exist to allow drivers to appropriately consider a potential safety event ahead of them. The product has been developed atop the rich traffic flow dataset that INRIX uses to produce segment level speeds.
INRIX takes real-time speeds from segment A, and the upstream segment B to determine if there is a greater than 45 mph delta suggesting a slowdown where drivers would need to take avoidance actions. Where a qualifying difference in speeds exists a DSD is placed at the upstream end of segment A. DSDs are assigned a severity based on the difference in miles per hour from segment B to segment A (segment = XDS or INRIX XD Segment).
Not all areas of congestion will produce a DSD. If there is a queue where speeds gradually slow over multiple segments this may not trigger the >45 mph minimum threshold between segments and therefore may not trigger the creation of a DSD. In this way DSD differ from Congestion Alerts. DSD are intended to describe a point in space where severe braking occurs. DSD generation is dependent on real-time data densities and therefore the prevalence of DSD may differ by geographic area, time of day, and day of week.
Q and A on Dangerous Slowdowns:
Q: Are Dangerous Slowdowns based on real-time data?
A: Yes. DSD are calculated based on real time data from multiple segments where the speed delta between a target segment and the upstream (XDS) segment is considered. A DSD is created when the speed delta from the two segments is greater than 45 MPH. If a DSD is expected but INRIX has not created an alert it may be due to trigger thresholds not being met (>45MPH), or because insufficient real-time data was present to conclude the rapidity of the slowdown
Q: Are the alerts filterable by severity?
A: Yes, each DSD is assigned a severity based on the nature of the slowdown at the end of the queue; the severity rating is based on the speed difference between segments
Q: Where are DSD published?
A: On all limited access roadways.
Q: How long do DSD last?
A: Depends on the data that that the platform has available at the time. DSD can be ephemeral (1 minute) or persist for an hour. It just depends on what data we have available to consider for DSD calculation, and whether that data tips the thresholds we set.
Q: What does the DSD output look like?
A: Suggestion is that you review the documentation at docs.inrix.com. For a quick reference there is sample output to the left (output fields may change in the future as we move toward V2 of this product)
Q: Is the DSD feature included in the INRIX Mobile SDK?
A: Yes. For access to the Mobile SDK please discuss with INRIX sales engineers
Q: Is this an INRIX XD-only product?
A: Currently, yes.
Q: How often are DSDs calculated?
A: Once per minute
Q: Is there documentation for DSD?
A: Yes. The docs.inrix.com has onboarding documentation. Additional assistance can be provided by INRIX sales engineers.
Q: What are the severity thresholds for DSD? (can be toggled on Demo)
A: (3)35-45mph; (4)45-60mph; (5)>60mph [speed drop between segment B, and the downstream segment A]
Q: Does INRIX populate mile marker data?
A: Currently there is a placeholder for mile marker data which may be populated in the future. There is no unified reference of mile marker data for most countries and therefore additional work would be required to fulfill delivery of mile marker values. Please discuss this need with INRIX sales engineering staff
Description: Gets Dangerous Slowdown incidents in a specified region.
dsd-api.inrix.com/v1/DangerousSlowdowns
GET Gets Dangerous Slowdown incidents in a specified region.
Parameters
= required| Name | Located In | Type | Description |
|---|---|---|---|
| accesstoken | Query | String | A valid access token provided from the GET appToken API response. Alternatively, the accesstoken can be added to the request header instead of a url parameter using format 'Authorization: Bearer xxxx.xxx.xxxx'. |
| box | Query | String | “box” specifies two latitude and longitude pairs (using the WGS 84 datum) that outline a bounding box. The first lat/long pair should be the northwestern most point, and the second pair the southeastern most point. Format- [lat1]|[long1],[lat2]|[long2]. Either box or point and radius parameters are required. |
| point | Query | String | Used to select a region based on a point and radius. If used, other Location parameters cannot be used. Format- [lat]|[long]. Either box or point and radius or geoId parameters are required. |
| radius | Query | Double | Used to select a region based on a point and radius. If the Units parameter is set to Metric, the radius is measured in kilometers; if Units is set to US (the default), the radius is measured in miles. If used, other Location parameters cannot be used. Either box or point and radius or geoId parameters are required. |
| geoId | Query | Integer | Used to select a region based on a geography. “geoid” specifies the ID of the specified geography. For more information on how to obtain the ID, see GetGeography. When using a custom GeoId (previously created with CreateGeography), the first call will create cached files. Once these have been created the call will return the correct information. Using Geographies with a large area (e.g. countries) is not recommended. Either box or point and radius or geoId parameters are required. |
| units | Query | Integer | Use 0 for English units, 1 for metric. Default is 0. |
| accepts | Header | String | Use application/json for json format response and application/xml for xml format resposne. |
Requests
Example Get dangerous slowdowns in a box request
Queryhttps://dsd-api.inrix.com/v1/DangerousSlowdowns?box=47.77577|-122.207249,47.743362|-122.16227&units=1&accesstoken={token}
Responses
200 Success
{
"copyright": "Copyright INRIX Inc. 2021",
"versionNumber": "v1",
"createdDate": "2021-08-10T00:17:45.4714315Z",
"responseId": "2e492ce9-0383-42bf-90a0-01f46c6e4dde",
"result": {
"dangerousSlowdowns": [
{
"id": "10838851|1386931281",
"version": 4,
"severity": 3,
"speedBefore": 47,
"speedAt": 11,
"speedDelta": 36,
"location": {
"geometry": {
"type": "Point",
"coordinates": [
-81.2920913696289,
34.166831970214844
]
},
"segment": {
"type": "XDS",
"code": "1386931281",
"offset": 0
}
},
"schedule": {
"occurrenceStartTimeUTC": "2021-08-10T23:31:00.8371099Z"
},
"description": {
"roadName": "I-26|JAMES F BYRNES EXPY",
"direction": 1,
"mileMarker": ""
}
}
]
}
}Response Elements
| Property | Type | Description | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| dangerousSlowdowns | Array | An array of Dangerous Slowdowns | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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