Different lane counts in HERE RDF data: Why "Lanes From/To" and "Physical Number of Lanes" show different values for the same road segment

Symptoms

Customers may observe one or more of the following:

Different lane counts returned for the same road segment in HERE RDF data.
"Lanes From/To" values do not match "Physical Number of Lanes" values.
Lane counts appear lower than the visible number of lanes on the roadway.
Additional lane-level attributes exist although the reported lane count is smaller.
Confusion about which lane attribute should be used for navigation, ADAS, connectivity, or lane-level analysis.

Answer

The difference is expected. "Lanes From/To" and "Physical Number of Lanes" represent different lane concepts and are designed for different use cases. As a result, the values may legitimately differ for the same link.

1. Lanes From/To"

Lanes From/To" is a link-level attribute that represents the number of lanes available on the primary driving path of a road segment.
This attribute does not count all physical lane types. The following lane types are excluded:

Shoulder lanes
Ramp transition lanes
Turn lanes at intersections
Parking lanes
Dedicated bus, taxi, or truck lanes

Because only lanes relevant to the main travel path are counted, the reported value may be lower than the total number of visible lanes.
Typical usage:

Routing-related analysis
Main carriageway lane information
ADAS-related applications that require primary travel-path lane counts

Coverage: Coverage is generally available on roads included in ADAS content, typically Functional Class (FC) 1 through FC4 roads. Actual availability depends on country, road class, and ADAS content coverage.

2. Physical Number of Lanes

"Physical Number of Lanes" is also a link-level attribute, but it represents the total number of physical lanes associated with the link.
Unlike "Lanes From/To", this attribute counts all lane types that are represented within lane-level content. It is used together with lane-related objects and attributes such as:

Extended Lanes
Lane Traversal Conditions
Lane-level connectivity
RDF_Lane information

Since additional lane types are included, the value may be greater than the corresponding "Lanes From/To" value.

Typical usage:

Lane-level guidance
Connectivity modeling
Advanced navigation applications
Detailed lane analysis and visualization

Coverage: Coverage is more selective and is primarily available on links where lane-level attribution exists. Availability is therefore tied to the presence of lane-related content such as Extended Lanes, Lane Markings, and lane connectivity information. Coverage is not expected to be continuous across all road classes.

Root Cause

The two attributes are derived from different lane attribution models:

Lanes From/To counts lanes on the primary driving path only.
Physical Number of Lanes counts all applicable physical lanes represented in lane-level content.

Because the counting rules differ, identical values should not be expected.

Impact

Selecting the wrong attribute can lead to:

Incorrect lane-count comparisons
Misinterpretation of roadway complexity
Inaccurate analytics results
Confusion when validating map content against field observations

Recommended Action

Use Lanes From/To when the requirement is to understand the number of lanes available for the primary travel path.

Use Physical Number of Lanes when the requirement is to understand total physical lane availability or when working with lane-level features such as connectivity, lane traversal conditions, lane markings, or Extended Lanes.

Expected vs. Unexpected Behavior

Expected

Different values between "Lanes From/To" and "Physical Number of Lanes".
Lower lane counts in "Lanes From/To" where turn lanes, bus lanes, parking lanes, or other excluded lane types exist.
Physical Number of Lanes" available only where lane-level attribution is present.

Unexpected

Missing lane counts where coverage is documented as available.
Values that contradict lane-level content definitions within the same release and geography.

Products

HERE Road Database Format (RDF)
HERE Core Map Content
ADAS Map Content
RDF Reference Manual v2026.02

Keywords / Tags

HERE RDF, Lanes From To, Physical Number of Lanes, lane count mismatch, lane attribution, RDF Lane, Extended Lanes, Lane Traversal Conditions, lane connectivity, ADAS coverage, Functional Class roads, road geometry, lane markings, Mosaic coverage, core map data