Where to start….

             The map-spat.com site divides the MAP-SPaT information into several general categories. Basic Lanes Types  (the core building blocks for all maps) Maneuvers at the Stop Line  (establishing what each lane is allowed to do at the stop line) Lane Attributes  (a rich methodology used to describe lane […]

Elevation uses in MAP-SPaT

This article describes issues with the vertical dimension of the LLH positions used in the DSRC work; particularly with respect the MAP applications. First some basics In the SAE DSRC system “height” means the height above the reference ellipsoid described by WGS84 expressed in units of 10 centimeter steps.  It […]

The Michigan Left Turn

In the state of Michigan it is common to extend the left turn lane past the intersection and make it an effective u-turn lane. Sometimes these lane have a signal controller and a phase state, while at other times they are simply un-signalized with a yield to on-coming traffic.  Both […]

On Placing Stoplines

This article deals with the mechanical details of where to place your “control” stop lines. Drawing the stop line, as well as many other control lines is preliminary step before beginning to capture the lane center lines when creating a map. This overall process is discussed further in this (to […]

Movement & Phase State

In the J2735 and J2945 MAP_SPaT work a “Phase” refers to a movement phase state of a signal system.  In other words the red-yellow-green signal colors that appear at the signal head. Although we go to very great lengths to avoid using “colors” to describe this.  And from the ISO […]

Maneuvers, General Concepts

In the J2735 and J2945 MAP_SPaT work a “Maneuver” refers to a single driving action needed to proceed from one lane to another at a defined nexus point, typically past a stop line at an intersection.  The entry is a Bit String which allow combining the various flag as needed. […]

Who is Jay Lewis?

Stupid Trivia Time Jay Lewis:  A pseudonym for the SCSC support staff that maintains this web site.  Most of the articles are penned by David Kelley (long time editor of the SAE DSRC J2735 Message set standard and the primary developer of the MAP-SPaT messages and well as many other […]

Right-on-red lane maneuvers

Encoding a right on red lane maneuver is a common need for the right-most lane in many intersections.  This article addresses how encode this and other “static” or “semi-static” maneuvers in a motor vehicle lane.   Often, defining this type of maneuver does not involve the use of the SPaT message.  […]

Regional data extensions in a generic lane object

In this article we discuss the topic of how to add regional data extensions to a map’s generic lane object.  The process steps are the same for adding content to any data concept with a regional extension. Extending MAP-SPaT with regional content is a fairly simple process. This need occurs […]

ASN.1 Viewer/Editor

ASN.1 Viewer/EditorTool The tool “ASN1VE” or ASN.1 Viewer/EditorTool is a useful ASN editing tool sold by Objective Systems. You can download it here:  https://www.obj-sys.com/products/asn1ve/index.php We often use screen shots taken from this tool in the developed examples shown here and in the graphics of IEEE and SAE standards that SCSC […]