Introduction

The Selected Link API calculates the distribution of incoming and outgoing trips through a defined region called “link”.

Common use cases

Thanks to the Selected Link API, you can tap into different insights and analysis, such as:

• How much traffic leaves a highway and drives through downtown to avoid congestion.
• Determine corridors for new or expanded roads.
• Alternative routes to manage construction.
• Planning detours.
• Intersection dependencies among multiple segments.
• And much more!

Using this API

This API is asynchronous. There are some important notes about using this API:

• The latitude and longitude coordinates are in EPSG4326 / WGS84 format for both input and output. Other coordinate systems are not supported.
• The link can be a GeoJSON LineString or a GeoJSON Polygon. The longest supported LineString is 2 km (1.24 miles) and the largest supported Polygon is 3 km^2, unless a higher area limit is granted to your contract.
• As the service is asynchronous it can take a while before results are available, depending on how busy the service is.
• The results of an analysis are released once it reaches the ACCEPTED status. Until then the response of Analysis Preview carries no result URLs.
• Do not repost your request multiple times if you do not get feedback within seconds. We will ensure to deliver the results.

Analysis version 2

The version of the analysis is not the version of the service. The 1 in the request URL is the version of the service and it does not change. To create a version 2 analysis, send "analysisVersion": 2 in the body of the creation request. A request that omits the field creates a version 1 analysis, which is documented at Selected Link Analysis (version 1).

What a version 2 analysis gives you:

• Traffic shares. Every node of the result carries percentage, its share of the traffic of the selected link, together with marginOfError, the half width of a 95% confidence interval.
• Trips inside a region. For a Polygon link, a third result direction, INSIDE, describes the trips within the region, with the geometry of every node clipped to it.
• Road names. Every node reports the name of its last road segment.
• Optional enhanced metrics. TRAVEL_TIME_AND_DISTANCE adds the average travel time and traveled distance to every node, and VOLUME adds the estimated absolute traffic volume. VOLUME requires traffic volume data to be available for the requested link and date ranges, and has further prerequisites, see Enhanced metrics.
• A single path at a time. Results can be filtered down to one path of the tree, across all time ranges of a date range, see Filtering results by path hash.

Note: all version 2 analyses are calculated on TomTom Orbis Maps.