Method for creating speed profiles for digital maps

Abstract

Probe data collected at times of low traffic density is analyzed to derive a Raw Road Design Speed Limit (RRDSL,) for each road segment or group of segments in a digital map. The RRDSL (), comprised of longitudinally distributed speeds, is associated with the road segment and stored in a digital medium to indicate the limits of the road section in free flow traffic. The longitudinally distributed speeds may be limited by local speed limits or other business logic to establish a Legal Raw Road Design Speed Limit (LRRDSL,). Either the RRDSL () or the LRRDSL () can be further modified to smooth acceleration and deceleration rates between changes in the longitudinally distributed speeds to create an Optimal Longitudinal Speed Profile (OLSP,), which represents optimized energy consumption. A signal can be produced if a driver's current speed rises unacceptably above a longitudinally distributed speed in real time. The signal can be audible, visible and/or haptic. Real-time traffic density information can be inferred by comparing current speed data to the longitudinally distributed speed for that position. If the current speed is consistently lower than the longitudinally distributed speed for that position, an inference is drawn that the road section is inefficient. Road efficiency assessments can be transmitted to a service center and/or other vehicles, and used by navigation software.