Module 62 - CV273
CV273: Introduction to SPaT / MAP Messages
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Slide 1:
![This slide contains a graphic with the word “Welcome” in large letters. ITS Training Standards “WELCOME” slide, with reference to the U.S. Department of Transportation Office of Assistant Secretary for Research and Technology](cv273ppt1.jpg)
Slide 2:
Welcome
![This slide contains a graphic with the word “Welcome” in large letters, photo of Kenneth Leonard, Director ITS Joint Program Office - Ken.Leonard@dot.gov - and on the bottom is a screeshot of the ITS JPO website - www.its.dot.gov/pcb](cv273ppt2.jpg)
Ken Leonard, Director
ITS Joint Program Office
Ken.Leonard@dot.gov
ITS PCB Home
Slide 3:
Module CV273:
Introduction to SPaT / MAP Messages
![Title slide: This slide contains the title with a placeholder graphic of a vehicle wirelessly communicating with a traffic signal. There are three yellow rings around the traffic signal and three yellow rings around the vehicle, indicating wireless communication.](cv273ppt4.jpg)
Source: US Department of Transportation
Slide 4:
Instructor
![Photo of Patrick Chan, P.E., Senior Technical Staff, Consensus Systems Technologies](cv273ppt5.jpg)
Patrick Chan, P.E.
Senior Technical Staff
Consensus Systems Technologies
Flushing, NY, U.S.A.
Co-Author:
Anu J. (AJ) Lahiri
Technical Staff
Consensus Systems Technologies
Slide 5:
Learning Objectives
- Describe the scope of the SAE J2735 Standard
- Describe the SPaT Message
- Describe the MAP Message
- Implementation Considerations
Slide 6:
Learning Objective 1
Describe the scope of SAE J2735 Standard
Slide 7:
What is a Connected Vehicle Environment, in Particular V2I Environment Transportation Challenges
![The slide entitled "What is a Connected Vehicle Environment, in particular a V2I Environment", with the subtitle "Transportation Challenges" contains a graphic. The top row contains a gray box entitled "Safety" and stating "37,113 highway deaths in 2017" and "6,452,000 crashes in 2017" To the right of the gray box is a picture of a motor vehicle collision. To the left of the gray box is a circle that indicates a speed limit. The second row contains an orange circular icon showing a roadway with an upward facing arrow. To the right of the icon is a blue box entitled "Mobility" and stating "5.5 billion hours of travel delay" and "$166 billion cost of urban congestion." To the right of the blue box is a picture of a multilane freeway with traffic congestion in both directions. The third line contains a green circular icon with the recycling symbol, and two thirds of a car. To the right of the icon is a green box entitled "Environment," and stating "3.3 billion gallons of wasted fuel". To the right of the green box is a picture of a single line of cars in congestion, with heavy exhaust seen coming from each vehicle.](cv273ppt6.jpg)
Source: US Department of Transportation, 2019 Urban Mobility Report, TTI
![Background information icon indicates general knowledge that is available elsewhere and is outside the module being presented.](cv273pptiminfo.jpg)
Slide 8:
What is a Connected Vehicle Environment, in Particular a V2I Environment
The CV Environment
![The slide entitled "What is a Connected Vehicle Environment, in particular a V2I Environment", with the subtitle "The CV Environment" contains three graphics stacked on top of each other on the left side. On top is a graphic with three vehicles on the road each with three yellow rings around each vehicle indicating each vehicle is wirelessly communicating. At the bottom, text says "Wirelessly Connected Vehicles". Below is a second graphic that shows a pedestrian crosswalk looking at a phone that shows a walk sign, meaning it is okay to walk. At the bottom, text says "Mobile Devices". Below is a third graphic that shows a cellular tower and building. At the bottom, text says "Infrastructure".](cv273ppt8.jpg)
Source: US Department of Transportation
CV environment consists of:
- Connected vehicles
- Connected individuals
- Connected infrastructure
CV Communications
- Wireless
-
Mixture of
- Short-range communications
- Remote communications
Slide 9:
What is a Connected Vehicle Environment, in Particular a V2I Environment
![The slide entitled "What is a Connected Vehicle Environment, in particular a V2I Environment" - The slide fully consists of a graphic of a connected vehicle environment. There is a four-way intersection with two cars and a bus, each at a different intersection approaches with three yellow rings around each vehicle indicating wireless communication. There is a pedestrian at one corner with a mobile phone that is indicating when it is okay to walk. There is a traffic light shown at the top with four bi-directional arrows, each one connected to a vehicle as well as the pedestrian. Using animation, the text "Current position and sensor data" appears over the bi-directional arrow to the bus representing vehicles providing their current position and sensor data. Using animation, the text "Current position and sensor data" appears over the bi-directional arrow to the pedestrian, representing individuals providing their current position and sensor data via connected devices. Using animation, the text "infrastructure data" appears over the bi-directional arrow to a traffic pole and cabinet, representing the infrastructure providing infrastructure data.](cv273ppt9.jpg)
Source: US Department of Transportation
Slide 10:
What is a Connected Vehicle Environment, in particular a V2I Environment
![The slide entitled "What is a Connected Vehicle Environment, in particular a V2I Environment" - The slide fully consists of a graphic of a connected vehicle environment. There is a four-way intersection with three cars and a bus at different intersection approaches, each of which have three yellow rings to show they are wirelessly communicating. There is a beacon at one corner, as well as transponders in the crosswalk. There are three pedestrians shown in the crosswalk. There is a walk sign shown at the corner. One pedestrian is carrying a mobile phone that shows a walk sign meaning pedestrians can cross. There are arrows from the transponders in the crosswalk pointing towards the beacon at the corner. There is are arrows connecting the beacon at the corner to a vehicle waiting. There is a caution sign next to the vehicle that indicates that the driver is receiving a warning to be cautious and yield to the pedestrians in the crosswalk.](cv273ppt10.jpg)
Source: US Department of Transportation
Slide 11:
What is the Need for SPaT and MAP Information?
- Signal Phase and Timing (SPaT) data and MAP data
![The slide entitled "What is the need for a SPaT and MAP information?", with the subtitle "Signal Phase and Timing (SPaT) data and MAP data" has a single graphic. The graphic shows a Traffic Management Center on the left side and a Traffic Signal Controller on the lower left side. In the center there is a Roadside Unit. Using animation, a red circle appears around an arrow that that says "SPaT data" from the Traffic Signal Controller to the Roadside Unit. Using animation a red circle appears around an arrow that that says "MAP data" from the Traffic Management Center to the Roadside Unit. Using animation, a red circle appears around an arrow flowing from the Roadside Unit that says "SPaT/MAP messages" to a pedestrian, a car, and a bicycle on the right side.](cv273ppt11.jpg)
Slide 12:
What is the Need for SPaT and MAP Information?
-
Signal Phase and Timing (SPaT) data are used by applications to generate:
- Pedestrian warnings: allowed pedestrian movements
- Driver warnings: potential red light violations, potential pedestrian conflicts, allowed vehicle movements
- Driver advisories: suggested travel speeds (for mobility and environmental purposes)
![The slide entitled "What is the need for a SPaT and MAP information?", with the subtitle "Signal Phase and Timing (SPaT) data are used by applications to generate", has a graphic on the right side. The graphic shows the view the interior of a vehicle through the windshield and a screen on the center console of the vehicle. The vehicle is approaching an intersection with red lights shown at the top. Wireless symbols are shown between the vehicle, indicating wireless communication is occurring, and a message appears on the center console saying "Stop Ahead" in response to the red traffic signal.](cv273ppt12.jpg)
Source: US Department of Transportation
Slide 13:
What is the Need for SPaT and MAP Information?
-
MAP data can be used by applications to provide benefits at intersections or roadway segments
- Driver warnings: sharp curves, allowable movements
- Driver advisories: location of lanes
- Pedestrian advisories: location of crosswalks
- Required to link SPaT data (currently allowable movements) with lanes
![The slide entitled "What is the need for a SPaT and MAP information?", with the subtitle "MAP data can be used by applications to provide benefits at intersections or roadway segments", has a graphic on the right side. The graphic shows an aerial schematic of a four-way intersection. The main street is shown east-west and have four lanes-two in each direction and the side street is shown to have two lanes in the north-south directions. The lanes approaching the intersection from the east have straight arrows indicating that only thru traffic is permitted from those lanes. The leftmost lane approaching the intersection from the west had a left turn arrow meaning that only left turns are allowed from the lane while the rightmost lane from the west is a straight arrow. The two side streets have a straight arrow and right turn arrow on the approaches to the intersection, indicating thru or right turns are allowed.](cv273ppt14.jpg)
Slide 14:
What is the Need for SPaT and MAP Information?
- Applications:
- Red Light Violation Warning (RLVW): warnings to travelers for impending red light violations
- Pedestrian in Signalized Crosswalk Warning: warnings to transit operators when pedestrians are in the intended path of the bus
- Mobile Accessible Pedestrian Signal System (PED-SIG): automated calls from a visually impaired pedestrian and cues to safely navigate the crosswalk
- Eco-Approach and Departure at Signalized Intersections: recommend speed trajectories as vehicles approach and depart the intersection
Source: US Department of Transportation
Slide 15:
What is the Scope and Purpose of SAE J2735?
-
A data dictionary for the CV environment.
- Defines messages and data elements
- Includes vehicle kinematic information, position correction information, traveler information
![Author's relevant description for this figure: This figure is for example purposes only: The slide entitled "What is the scope and purpose of SAE J2735", with the subtitle "A data dictionary for the CV environment", has a graphic on the right side. The graphic shows the title page of the SAE J2735_201603 standard.](cv273ppt15.jpg)
Source: SAE International
Slide 16:
What is the Scope and Purpose of SAE J2735?
-
Signal Phase and Timing (SPaT)
-
Provides signal phase and timing data from one or more traffic signal controllers
- Provides dynamic data
- General controller status
- What movements (by lane) are currently allowed and when will the movement state is likely to end
- Tied to the MAP data message
![The slide entitled "What is the scope and purpose of SAE J2735", with the subtitle "Signal Phase and Timing SPaT", has a graphic on the right side. The graphic shows a screenshot of a mobile application. The application displays information for a driver in a vehicle approaching an intersection. The top of the screen shows the name of the application: "TravelSafely". Below is text identifying the driver's current location: "City of Anaheim". Below is text identifying the intersection that the driver is approaching: "Anaheim Blvd-Lincoln Ave". Below are large arrows. On the center right side, a green arrow is pointing up, indicating that thru traffic is currently permitted by the traffic signal. On the center left is a red left turn arrow, indicating that left turns are currently not permitted by the traffic signal. Below the red arrow is text that says "80+ Seconds to Green", indicating that it will more than 80 seconds until left turns at the intersection will be permitted. At the bottom are three buttons. The leftmost button shows a gear icon that may show application settings. The rightmost button shows a question mark that may show application tips. The center button shows a car.](cv273ppt16.jpg)
Source: Applied Information
Slide 17:
What is the Scope and Purpose of SAE J2735?
-
MAP Data Message
-
Provides static roadway geometric information
- Lane widths, path, location
- Lane types - vehicle lanes, crosswalks, barriers
- Lane attributes - allowable movements, safe landing zones for the visually impaired
- Indicates what part of the SPaT message applies to the traveler's intended movement
![The slide entitled "What is the scope and purpose of SAE J2735", with the subtitle "Signal Phase and Timing SPaT", has a graphic on the right side. The same graphic as Slide 13 is shown. The graphic shows an aerial schematic of a four-way intersection. The main street is shown east-west and have four lanes-two in each direction and the side street is shown to have two lanes in the north-south directions, one in each direction. The lanes approaching the intersection from the east have straight arrows indicating that only thru traffic is permitted from those lanes. The leftmost lane approaching the intersection from the west had a left turn arrow meaning that only left turns are allowed from the lane while the rightmost lane from the west is a straight arrow. The two side streets have a straight arrow and right turn arrow on the approaches to the intersection, indicating thru or right turns are allowed.](cv273ppt17.jpg)
Slide 18:
What is the Scope and Purpose of SAE J2735?
-
Signal Request / Signal Status Message (SRM/SSM)
- Provides signal priority/preemption request and status messages
- Uses approach and desired egress lane, and estimated times
- Must be configured to work reliably and with security protections
![The slide entitled "What is the scope and purpose of SAE J2735", with the subtitle "Signal Request/Signal Status Message (SRM/SSM)", has a graphic on the right side. The graphic shows a signalized intersection with two buses and a truck, each vehicle having three yellow rings around it to indicate wireless communication. Arrow flows are shown from a bus communicating with a beacon on the sidewalk. Arrow flows are shown pointing from the beacon to the intersection's traffic signal controller at the corner of the intersection. Finally, arrow flows are shown from the traffic signal controller to the traffic signal.](cv273ppt18.jpg)
Source: US Department of Transportation
Slide 19:
What is the Scope and Purpose of SAE J2735?
-
Basic Safety Message
- Broadcasted by vehicles about their kinematics and sensor information
-
Traveler Information Message
- General traveler information broadcasted from the infrastructure to travelers
-
NMEA Corrections and RTCM Corrections
- Contains data used to calibrate GNSS (e.g., GPS) for vehicles and mobile devices to increase the absolute and relative location accuracy.
Slide 20:
![Activity Placeholder: This slide has the word “Activity” in large letters at the top of the slide, with a graphic of a hand on a computer keyboard below it.](cv273ppt19.jpg)
Slide 21:
Question
Which of the following user needs for a signalized intersection is NOT addressed with SPaT data?
Answer Choices
- Receive currently allowed vehicle movements
- Receive lane location descriptions
- Receive suggested vehicle speeds
- Receive estimated times when signal indications will change
Slide 22:
Review of Answers
a) Receive currently allowed vehicle movements
Incorrect.
This information is supported by SPaT data
b) Receive lane location descriptions
Correct! Lane location descriptions are provided by MAP message data
c) Receive suggested vehicle speeds
Incorrect. This information is supported by SPaT data
d) Receive estimated times when signal indications will change
Incorrect. This information is supported by SPaT data
Slide 23:
Learning Objective
Describe the SPaT Message
Slide 24:
What is the Structure of the SPaT Message?
-
Previously described WHY SPaT data is needed
- Support in-vehicle and individual applications
- Next several slides describes WHAT data is provided in SAE J2735_201603
Slide 25:
What is the Structure of the SPaT Message?
Slide 26:
What is the Structure of the SPaT Message?
![The slide titled "What is the structure of the SPaT message?" has a graphic showing a sample SPaT message. On top is a blue box labeled "MSG_SignalPhaseAndTiming" that represents the message. Below are five data concepts that are attributed to it. The first box is a green box labeled messageId. The next box is a yellow box labeled timeStamp. The next box is a yellow box labeled name. The next box is a green box labeled intersections. Under the intersections box is a note that says 1..32 indicating that it is a data frame that holds data for up to 32 intersections. The last box is a yellow box labeled regional. A legend appears on the right indicating green boxes are mandatory elements and yellow boxes are optional elements.](cv273ppt22.jpg)
- messageId. DE_DSRCmsgID = 19
- timeStamp. Number of elapsed minutes in the year
- name. Name of the group of intersections for testing purposes
- intersections. Data for each intersection
- regional. Regional extensions
Slide 27:
What is the Structure of the SPaT Message?
![The slide titled "What is the structure of the SPaT message?" has a graphic showing a sample SPaT message. This is the same as Slide #26. On top is a blue box labeled "MSG_SignalPhaseAndTiming" that represents the message. Below are five data concepts that are attributed to it. The first box is a green box labeled messageId. The next box is a yellow box labeled timeStamp. The next box is a yellow box labeled name. The next box is a green box labeled intersections. Under the intersections box is a note that says 1..32 indicating that it is a data frame that holds data for up to 32 intersections. The last box is a yellow box labeled regional. A legend appears on the right indicating green boxes are mandatory elements and yellow boxes are optional elements.](cv273ppt23.jpg)
-
Each SPaT message can provide signal phase and timing and dynamic information for multiple intersections.
- Useful in dense urban areas.
Slide 28:
What are the Mandatory Elements of the SPaT Message?
![The slide titled "What are the mandatory elements of the SPaT message?" fully consists of a graphic that shows the structure of intersections data frame. There are three levels to the structure of the data. On the first level is a green box labeled intersections representing the intersections data frame. Under the intersections box is a note that says "1..32" indicating that it is a data frame that holds data for up to 32 intersections. On the second level are 10 boxes with black lines connected to intersections box on the top level indicating that they are elements in intersections. The first box is a yellow box labeled name. The second box a green box labeled id. The third box is a green box labeled revision. The fourth box is a green box labeled status. The fifth box is a yellow box labeled moy. The sixth box is a yellow box labeled timeStamp. The seventh box is a yellow box labeled enabledLanes. The eighth box is a green box labeled states. The ninth box is a yellow box labeled maneuverAssistList. The tenth box is a yellow box labeled regional. On the third level are two boxes with black lines connected to the green box labeled id on the second level indicating these two boxes are elements of the id data frame. The first box a yellow box labeled region. The next box is a green box labeled id. A legend appears on the left indicating green boxes are mandatory elements and yellow boxes are optional elements.](cv273ppt24.jpg)
- region. Identifier of the responsible agency
- id. Regionally unique intersection identifier
Slide 29:
What are the Mandatory Elements of the SPaT Message?
![The slide titled "What are the mandatory elements of the SPaT message?" fully consists of a graphic that shows the structure of intersections data frame. This graphic is similar to the graphic on Slide #28 except there are only two levels of the structure of the data. On the first level is a green box labeled intersections representing the intersections data frame. Under the intersections box is a note that says "1..32" indicating that it is a data frame that holds data for up to 32 intersections. On the second level are 10 boxes with black lines connected to intersections box on the top level indicating that they are elements in intersections. The first box is a yellow box labeled name. The second box a green box labeled id. The third box is a green box labeled revision. The fourth box is a green box labeled status. The fifth box is a yellow box labeled moy. The sixth box is a yellow box labeled timeStamp. The seventh box is a yellow box labeled enabledLanes. The eighth box is a green box labeled states. The ninth box is a yellow box labeled maneuverAssistList. The tenth box is a yellow box labeled regional. A legend appears on the left indicating green boxes are mandatory elements and yellow boxes are optional elements.](cv273ppt25.jpg)
-
revision is message counter. Increments:
- Every time message is transmitted, OR
- When the message content changes
- status is the general status of the controller, e.g., adaptive, priority, preempt, flash, no valid SPaT data
Slide 30:
What are the Mandatory Elements of the SPaT Message?
-
Status. Example potential implementation issues:
-
Definition of providing signal priority.
- When request is received?
- When modifications are made to the timing?
-
Definition of preempt mode.
- When the preempt request is received?
- Does it include the preempt exit phases?
-
Definition of recent MAP update.
- Within the last week? Last month?
- Some status values may be defined in other standards, e.g., NTCIP 1202 v03
Slide 31:
What are the Mandatory Elements of the SPaT Message?
![The slide titled "What are the mandatory elements of the SPaT message?" fully consists of a graphic that shows the structure of intersections data frame. This graphic is similar to the graphic on Slide #28 for the first two levels. On the first level is a green box labeled intersections representing the intersections data frame. Under the intersections box is a note that says "1..32" indicating that it is a data frame that holds data for up to 32 intersections. On the second level are 10 boxes with black lines connected to intersections box on the top level indicating that they are elements in intersections. The first box is a yellow box labeled name. The second box a green box labeled id. The third box is a green box labeled revision. The fourth box is a green box labeled status. The fifth box is a yellow box labeled moy. The sixth box is a yellow box labeled timeStamp. The seventh box is a yellow box labeled enabledLanes. The eighth box is a green box labeled states. The ninth box is a yellow box labeled maneuverAssistList. The tenth box is a yellow box labeled regional. On the third level are four boxes with black lines connected to the green box labeled states indicating they are elements in the states data frame. The first box is a yellow box labeled movementName. The second box is a green box labeled signalGroup. The third box is a green box labeled state-time-speed. The last box is a yellow box labeled maneuverAssistList. A legend appears on the left indicating green boxes are mandatory elements and yellow boxes are optional elements.](cv273ppt26.jpg)
- states provide information for each movement at the intersection
- signalGroup is an identifier tying the SPaT data to a specific lane-to-lane movement in the MAP message
Slide 32:
What are the Mandatory Elements of the SPaT Message?
- eventState. Unavailable, dark (signal indication is dark), stop then proceed (e.g., flashing red, red turn on red), stop and remain, permissive movement, protected movement, permissive clearance, protected clearance, proceed with caution (e.g., flashing yellow)
Slide 33:
What are the Mandatory Elements of the SPaT Message?
![The slide titled "What are the mandatory elements of the SPaT message?" fully consists of a graphic that shows an aerial schematic four-way intersection. The main street traveling east-west is shown to have four lanes-two in each direction and the side street travelling north-south is shown to have two lanes, one in each direction. Each lane on the approaching the intersection has arrows indicating possible turns that are allowed from the lane. The lanes approaching from the west show a straight green arrow on the right lane that says "permissive" indicating a permissive thru movement from that lane. The left lane has a back left turn arrow that says "protected" indicating a protected left turn. All other lanes approaching the intersection has red arrows that say "stop and remain" indicating that movement from those lanes is not permitted. Using animation, a red circle surrounds the westbound permissive green through arrow. Then, a red circle surrounds the westbound protected left green arrow. Finally, a red circle surrounds each of the red arrows for all other movements at the intersection.](cv273ppt28.jpg)
Slide 34:
What are the Mandatory Elements of the SPaT Message?
-
Summary
- messageId
-
Intersection (optional)
- id (of the intersection)
- revision (counter)
- status (of the controller)
-
state
- signalGroup (identifier of the movement)
- eventState (signal state of the movement)
Slide 35:
What are the Optional Elements of the SPaT Message?
-
Enabled (revocable) lanes
- List of revocable lanes that are active
- Must be defined as a revocable lane in the MAP message
Slide 36:
What are the Optional Elements of the SPaT Message?
![The slide entitled "What are the optional elements of the SPaT message?" contains a graphic on the left side. The graph shows a schematic of a road with three different lanes. The left most lane has dashed yellow lines on both sides indicating it's a reversible lane and has two yellow arrows, one pointing north and one pointing south, indicating travel in both directions are allowed (but not simultaneously). On top of the lane is number 201 indicating the lane identifier for travel in the northbound direction. At the bottom of the lane is number 211 indicating the lane identifier for travel in the southbound direction. The rightmost lane has dashed lines on the left side and a solid line on the right side indicating a sidewalk. There is a white arrow pointing north to indicate travel in the lane is in the northbound direction. On top of the lane, there is number 203 indicating the lane identifier for travel in the northbound direction. At the bottom is a bold P to indicate that the lane is used for parking. Below is the number 205 indicating the lane identifier when the lane it is used for parking. The middle lane has a white arrow pointing north to indicate the lane is used for traffic in the northbound direction. On top of the lane, there is number 202 indicating the lane identifier.](cv273ppt29.jpg)
Lane 201, 203, 211, 205 are revocable lanes
- Revocable lanes may be mutually exclusive
- Lanes 201 and 211 are reversible lanes
- Lane 203 is an active lane and Lane 205 is a parking lane
Slide 37:
What are the Optional Elements of the SPaT Message?
-
timing. Measured in tenths of a second in the current or next hour.
- Time OF change, not time TO change.
- NOT valid if in preempt mode
-
minEndTime. Earliest time the eventState may change (mandatory)
- How to interpret for actuated signals if the minEndTime has already passed?
- startTime. Ambiguous, could be past or future
![Contains a graphic on the right side of a traffic light.](cv273ppt30.jpg)
Slide 38:
What are the Optional Elements of the SPaT Message?
-
timing. (continued)
- maxEndTime. Latest time the eventState may change
- likelyTime. Most likely time the eventState will change
- confidence. Statistical probability of the likelyTime
- nextTime. When the current eventState will likely occur again
Slide 39:
What are the Optional Elements of the SPaT Message?
![Please see Extended Text Description below.](cv273ppt31.jpg)
(Extended Text Description: Author's relevant description for this figure: This slide entitled "What are the optional elements of the SPaT message?" fully consists of a chart that shows the values for the states data frame for the SPaT message for specific timepoints along the x-axis within a full signal cycle. At the top are two color bars (red, green, yellow) showing the signal indication for main street green and the cross street as time progresses through the cycle length. Below is text indicating timestamps at which data was recorded. Data was recorded at:
- 10:59:58:0 (all-red)
- 11:00:00:0 (two seconds later, beginning of main street green)
- 11:00:06:0 (six seconds later)
- 11:00:12:0 (six seconds later, end of minimum green for main street green)
- 11:00:24:0 (12 seconds later, end of maximum green for main street green)
- 11:00:25:5 (1.5 seconds later, halfway through the yellow clearance interval)
- 11:00:27:0 (1.5 seconds later, beginning of the red clearance interval)
- 11:00:29:0 (two seconds later, beginning of cross street green)
- 11:00:36:0 (seven seconds later, end of minimum green for cross street green)
- 11:00:45:0 (nine seconds later, end of maximum green for cross street green)
- 11:00:48:0 (three seconds later, end of yellow clearance interval)
Below the time points is a chart with data values for each timestamp. The first row contains the timeStamp (in tenths of a second within the current hour) as it would appear in the SPaT message. Below this row is data values for each signal group - signalGroup 2 for main street and signalGroup 4 for the cross street. The following data is recorded:
- startTime (in tenths of a second within the current hour)
- minEndTime (in tenths of a second within the current or next hour)
- maxEndTime (in tenths of a second within the current or next hour)
- likelyEndTime (in tenths of a second within the current or next hour)
- nextTime (in tenths of a second within the current or next hour)
- eventState (an integer)
)
![Example icon. Can be real-world (case study), hypothetical, a sample of a table, etc.](cv273pptimexample.jpg)
Slide 40:
What are the Optional Elements of the SPaT Message?
-
Advisory speeds for a movement
- The advisory speed and distance from the stop bar the advisory speed is good for
- Specify the vehicle class the advisory is valid for
![Contains a graphic at the bottom with a sign that shows a recommended speed of 20 MPH](cv273ppt33.jpg)
Slide 41:
What are the Optional Elements of the SPaT Message?
-
Information for a specific lane movements
- Current queue length for this movement
- Distance from the stop bar within which vehicles can expect to clear the intersection
- If a vehicle should stop at the stop bar
- If a conflicting pedestrian or bicycle in the path is detected
- Requires a MAP message
![The slide entitled "What are the optional elements of the SPaT message?" contains a graphic on the right side showing an aerial view of an intersection with a westbound and northbound approach. The westbound approach is a four-lane road with two in each direction and the northbound approach is a two-lane road with one lane in each direction. Each lane has a number identifying the lane. There is a red turning arrow from the leftmost lane of the westbound approach to the northbound lane.](cv273ppt34.jpg)
Slide 42:
What are the Optional Elements of the SPaT Message?
-
Optional elements are optional as defined by the SAE J2735 standard
- Mandatory are minimum elements based on the experience of the standards committee
-
Optional elements should be broadcasted IF:
- Required by a regulation or regulatory agency
-
Required by another standard or specification
- E.g., the Connected Signalized Intersection project
Slide 43:
What are the Optional Elements of the SPaT Message?
-
Optional elements should be broadcasted if needed to support a desired application
- To support a basic Red Light Violation application, the mandatory elements are sufficient
- To support the Eco-Approach and Departure at Signalized Intersections application, the advisory speeds for an approach towards the intersection is needed
- To support phase time remaining in an in-vehicle application, the timing information is needed
Slide 44:
![Activity Placeholder: This slide has the word “Activity” in large letters at the top of the slide, with a graphic of a hand on a computer keyboard below it.](cv273ppt35.jpg)
Slide 45:
Question
Signal timing information for how many intersections can be included in a single SPaT message?
Answer Choices
- Only one signalized intersection
- Only one signalized and one non-signalized intersection
- Up to two signalized intersections along an arterial
- Up to 32 signalized intersections
Slide 46:
Review of Answers
a) Only one signalized intersection
Incorrect.
b) One signalized and one non-signalized intersection
Incorrect.
c) Up to two signalized intersections along an arterial
Incorrect.
d) Up to 32 signalized intersections
Correct! A SPaT message can provide signal timing information for up to 32 signalized intersections
Slide 47:
Learning Objective 3
Describe the MAP message
Slide 48:
What is the Structure of the MAP Message?
-
MAP messages provide static geographic road information
- descriptions of lanes and lane types
-
Each MAP message can provide roadway geometric information for:
- Up to 32 intersections, and
- Up to 32 road segments
Slide 49:
What is the Structure of the MAP Message?
![The slide entitled "What is the structure of the MAP message" has a graphic at the top showing the structure of the MAP message. There is a large blue box with text that says MSG_MapData representing the entire message. Below are nine boxes that represent elements of the MAP message. The first box is a green box labeled messageId. The second box is a yellow box labeled timeStamp. The third box is a green box labeled msgIssueRevision. The fourth box is a yellow box labeled layerType. The fifth box is a yellow box labeled layerId. The sixth box is a yellow box labeled intersections. The seventh box is a yellow box labeled roadSegments. The eighth box is a yellow box labeled dataParameters. The ninth box is a yellow box labeled restrictionList. A legend appears on the bottom left corner of the graphic indicating green boxes are mandatory elements and yellow boxes are optional elements.](cv273ppt37.jpg)
- messageId. DE_DSRCmsgID = 18
- timestamp. Number of elapsed minutes in the year
- msgIssueRevision. Message counter indicating contents changed
- layerType. Type of map information, e.g., general, curve, intersection, roadway segment
- layerId. Layer identifier
Slide 50:
What is the Structure of the MAP Message?
![The slide entitled "What is the structure of the MAP message" has the same graphic in Slide #49 showing the structure of the MAP message. There is a large blue box with text that says MSG_MapData representing the entire message. Below are nine boxes that represent elements of the MAP message. The first box is a green box labeled messageId. The second box is a yellow box labeled timeStamp. The third box is a green box labeled msgIssueRevision. The fourth box is a yellow box labeled layerType. The fifth box is a yellow box labeled layerId. The sixth box is a yellow box labeled intersections. The seventh box is a yellow box labeled roadSegments. The eighth box is a yellow box labeled dataParameters. The ninth box is a yellow box labeled restrictionList. A legend appears on the bottom left corner of the graphic indicating green boxes are mandatory elements and yellow boxes are optional elements.](cv273ppt38.jpg)
- intersections. MAP data for intersections
- roadSegments. MAP data for road segments
- dataParameters. Metadata about the MAP contents
- restrictionList. List of potential user class restrictions
Slide 51:
What are the Mandatory Elements of a MAP Message?
- id. Identifier of the responsible agency (optional) + regionally unique identifier for the intersection
- revision. Message counter to indicate if the road geometry for the intersection has changed
- refpoint. Geographic reference (anchor) point for this intersection. Latitude-Longitude. Elevation is optional.
- laneSet. Data describing a lane
![Remember icon. Used when referencing something already discussed in the module that is necessary to recount.](cv273pptimremember.jpg)
Slide 52:
What are the Mandatory Elements of a MAP Message?
![The slide entitled "What are the mandatory elements of a MAP message" has a graphic at the top showing the structure of the laneSet data frame. On top is a green box labeled laneSet. Under the laneSet box is a note that says 1..255 indicating that it is a data frame that holds data for up to 255 lanes. Below are nine boxes with black lines that are connected to the lane set data frame, indicating that they represent elements in the lane set data frame. The first box is a green box labeled laneId. The second box is a yellow box labeled name. The third box is a yellow box labeled ingressApproach. The fourth box is a yellow box labeled egressApproach. The fifth box is a green box labeled laneAttributes. The sixth box is yellow box labeled maneuvers. The seventh box is a green box labeled nodeList. The eighth box is a yellow box labeled connectsTo. The ninth box is a yellow box labeled overlays. A legend appears on the upper left corner of the graphic indicating green boxes are mandatory elements and yellow boxes are optional elements.](cv273ppt41.jpg)
- laneId. A lane identifier unique within the intersection
- laneAttributes. A data frame containing data about the lane characteristics
Slide 53:
What are the Mandatory Elements of a MAP Message?
![The slide entitled "What are the mandatory elements of a MAP message" has a graphic at the top showing the structure of the laneAttributes data frame. On top is a green box labeled laneAttributes. Under the data frame is a note that says 1..255 indicating that it is a data frame that holds data for up to 255 lanes. Below are three green boxes with black lines that are connected to the lane attributes data frame, indicating each represent elements of the lane attributes data frame. The first box is labeled directionalUse. The second box is labeled shareWith and the last box is labeled laneType. A legend appears on the upper left corner of the graphic indicating green boxes are mandatory elements and yellow boxes are optional elements.](cv273ppt42.jpg)
- directionalUse. Direction of travel in the lane
- sharewith. Indicates the presence of another user type that has equal rights to use the lane
-
laneType. Defines the type of lane. Valid values include vehicle lane, crosswalk, bicycle lane, sidewalk, (physical) barrier, striped lane, tracked vehicle and parking lane.
- Also used to indicate if it is revocable lane. Used by the SPaT message
Slide 54:
What are the Mandatory Elements of a MAP Message?
![The slide entitled "What are the mandatory elements of a MAP message" has a graphic at the top showing the structure of the laneSet data frame. This is the same graphic is on Slide #52 with an additional level. On top is a green box labeled laneSet. Under the laneSet box is a note that says 1..255 indicating that it is a data frame that holds data for up to 255 lanes. Below are nine boxes with black lines that are connected to the lane set data frame, indicating that they represent elements in the lane set data frame. The first box is a green box labeled laneId. The second box is a yellow box labeled name. The third box is a yellow box labeled ingressApproach. The fourth box is a yellow box labeled egressApproach. The fifth box is a green box labeled laneAttributes. The sixth box is yellow box labeled maneuvers. The seventh box is a green box labeled nodeList. The eighth box is a yellow box labeled connectsTo. The ninth box is a yellow box labeled overlays. A legend appears on the upper left corner of the graphic indicating green boxes are mandatory elements and yellow boxes are optional elements. The third level shows two green boxes with black lines connected to the nodeList box, indicating that they are elements in the node list data frame. The first box is labeled nodes and the second box is labeled computed.A legend appears on the upper left corner of the graphic indicating green boxes are mandatory elements and yellow boxes are optional elements.](cv273ppt43.jpg)
-
nodeList. Sequence of signed offset node points representing the centerline of the lane. CHOICE of:
- nodes. A sequence of 2 to 63 node points defining the centerline of the lane
- computed. A lane that has similar (lane) attributes as another lane
Slide 55:
What are the Mandatory Elements of a MAP Message?
![The slide entitled "What are the mandatory elements of a MAP message" has a graphic at the top showing the structure of the nodes data frame. On top is a green box labeled nodes. Below is a note that says 2..63 indicating that it is a data frame that holds data for 2 to 63 node points. Below are two boxes with black lines connected to the nodes data frame indicating that that they are elements in the nodes data frame. The first box is a green box labeled delta. The second box is a yellow box labeled attributes. A legend appears on the left indicating green boxes are mandatory elements and yellow boxes are optional elements.](cv273ppt44.jpg)
-
delta. Each node is an X-Y offset from the previous node, in units of 1 centimeter.
- Each node could also be a latitude-longitude geographic coordinate but not generally used
- The first node point is the offset from the reference point and typically at the stopline.
- With lane width represents the lane as a polygon
Slide 56:
What are the Mandatory Elements of a MAP Message?
![The slide entitled "What are the mandatory elements of a MAP message" has a graphic that shows an example aerial view of an intersection in New York City. There is a one-way main street from right to left with a total of six lanes. There is a one-way side street going down with a total of three lanes. Each lane is indicated with an orange line and a number that represents the lane identifier. There are nodes visible at the start of each lane at the stopbar of the adjacent intersection to the stopbar of that lane at the intersection. In the center of the intersection is a blue bubble that represents the reference point. There is also a crosswalk at each side of the intersection. Each crosswalk is indicated with an orange line and a node. There also red squares on each side of the intersection, indicating the locations of stop bars. There is a blue pin is at the traffic pole at the upper right corner of the intersection that is used as a survey point used by a tool that can be used to check for positional accuracy.](cv273ppt45.jpg)
Source: New York City Connected Vehicle Pilot
![Example icon. Can be real-world (case study), hypothetical, a sample of a table, etc.](cv273pptimexample.jpg)
Slide 57:
What are the Mandatory Elements of a MAP Message?
![The slide titled "What are the mandatory elements of a MAP message?" has a graphic at the top showing the structure of the computed data frame. There are two levels shown. The first level shows a green box that represents the computed lane data frame. The second level shows six boxes with black lines connected to the computed lane data frame, indicating that they are fields of the computed lane data frame. The first box is a green box labeled referencedLaneId. The second box is a green box labeled offsetXaxis. The third box is a green box labeled offsetYaxis. The fourth box is a yellow box labeled rotateXY. The fifth box is a yellow box labeled scaleXaxis. The last box is a yellow box labeled scaleYaxis. A legend appears on the left indicating green boxes are mandatory elements and yellow boxes are optional elements.](cv273ppt47.jpg)
- referencedLaneId. Identifier of the lane that this computed lane is based on.
- offsetXaxis / offsetYaxis. Offset of the first node of the computed lane from the referenced lane along the x-axis / y-axis
Slide 58:
What are the Mandatory Elements of a MAP Message?
![The slide entitled "What are the mandatory elements of a MAP message" has a graphic that shows an example aerial view of an intersection in New York City. There is a one-way main street going down with a total of seven lanes approaching the intersection. The rightmost lane approaching the intersection is represented by a dark blue line, meaning it is the original referenced lane using node offsets. The other six lanes on the approach are represented with a light blue line, indicating they are computed lanes based on the original reference lane. There are six lines on the main street leaving the intersection. Each of them has is indicated with a gray line. There are pink lines along the sides of the intersection representing pedestrian crosswalks. The side street has one three lanes leaving the intersection, each of them indicated with a gray line. The other side has eight lanes approaching the intersection. Going against the direction of the main street, the first lane is represented with a dark blue line, indicating node offsets. The second lane is represented by a light blue line and is a computed lane based on the first lane. The third is shorter than the first and is represented with a dark blue line. The fourth lane is shorter than the third and is represented with a dark blue line. The fifth lane is represented with a light blue line and is computed based on the fourth line. The sixth lane is leaving the intersection and is indicated with a gray lane. The seventh lane is approaching the intersection and is indicated with a dark blue line. The eighth lane is represented by a light blue line and was computed based on the seventh lane. In the center of the intersection is an orange bubble that represents the reference point. Each lane is labeled with its lane identifier.](cv273ppt48.jpg)
Source: New York City Connected Vehicle Pilot
![Example icon. Can be real-world (case study), hypothetical, a sample of a table, etc.](cv273pptimexample.jpg)
Slide 59:
What are the Mandatory Elements of a MAP Message?
-
Summary
- messageId
- msgIssueRevision (of the message)
- id (of each intersection)
- refPoint (of each intersection)
- revision (counter for each intersection)
-
For each lane:
- laneId
- laneAttributes
- nodes (sequence of node offsets)
Slide 60:
What are the Optional Elements of a MAP Message?
-
speedLimits. Regulatory information for a lane or set of lanes
- type. Type of regulatory speed limit.
- speed. Velocity of the object (in 0.02 m/s)
- Metadata about the map contents
- User class restrictions for lane/movement restrictions (e.g., transit only, emissions compliant, height compliant, pedestrians only)
Slide 61:
What are the Optional Elements of a MAP Message?
-
maneuvers. Allowed maneuvers for the lane
- connectingLane. Lane identifier that a maneuver connects to
- remoteIntersection. Identifier of another intersection that describes the connecting lane
- signalGroup. Identifier of the movement. Used to tie to the SPaT message.
- userClass. Identifies the lane/movement restrictions
Slide 62:
What are the Optional Elements of a MAP Message?
-
Node information. Presents the attributes at a node that describes the path of a lane.
- localNode. Defines up to 8 attributes for this node point. E.g., fire hydrant, traffic island for crosswalks
- disabled / enabled. Defines up to 8 attributes for a segment. E.g., transit stop, parking zone, bike lane on left, rumble strip present
- dWidth. Linear taper in the lane width from the previous node
- dElevation. Linear taper in the lane elevation from the previous node
Slide 63:
What are the Optional Elements of a MAP Message?
-
Computed Lane
- rotateXY. Rotation of the initial node point
- scaleXaxis / scaleYaxis. Defines expansion or contraction of the computed lane along the X-axis / Y-axis
Slide 64:
What are the Optional Elements of a MAP Message?
- Optional elements are optional as defined by the standard
- Optional elements may be required by a regulation, another standard or a specification
-
Optional elements should be broadcasted if needed to support an application
- Maneuver information, e.g., SignalGroupID data, is needed to support the SPaT message if broadcast
- Location of safety zones (e.g., traffic islands) for pedestrian safety applications may be needed.
Slide 65:
![Activity Placeholder: This slide has the word “Activity” in large letters at the top of the slide, with a graphic of a hand on a computer keyboard below it.](cv273ppt49.jpg)
Slide 66:
Question
Which of the following attributes for a lane is included in a MAP message?
Answer Choices
- The centerline locations of a lane
- The permitted direction of travel of the lane
- The permitted vehicle types that may use the lane
- All of the above
Slide 67:
Review of Answers
a) The centerline locations of a lane
True. Nodes are used to define the centerline of a lane.
b) The permitted direction of travel of the lane
True. The permitted direction of travel of the lane may be provided in a MAP message.
c) The permitted vehicle types that may use the lane
True. Vehicle class restrictions may be included in a MAP message.
d) All of the above
Correct! All of the above are true.
Slide 68:
Learning Objective 4
Implementation Considerations
Slide 69:
ISO TS 19091
-
Previously described WHY SPaT and MAP data is needed
- Support safety, mobility and environmental applications
- Previously describes WHAT data is provided by the SPaT and MAP messages
-
Next slides describe WHEN, WHERE, and HOW the data is provided to support interoperability
- Standards help answer some questions
- May depend on the application
Slide 70:
ISO TS 19091
-
ISO TS 19091 - Intelligent transport systems - Cooperative ITS - Using V2I and I2V communications for applications related to signalized intersections
-
Defines dialogs and HOW to exchange messages, data structures, and data elements between roadside units and travelers to support signalized intersection applications
- Procure, implement and test in a consistent manner
- Used in Europe
- May be used as guidance in North America
Slide 71:
ISO TS 19091
-
The V2I applications addressed in ISO TS 19091 are described by use cases
- Defines the operations between the actors
- Defines information needs for communication between vehicles and infrastructure
- Identifies information for the applications
-
Use case types
- Priority/Preemption applications
- Safety applications
- Mobility/Sustainability applications
![Supplement icon indicating items or information that are further explained/detailed in the Student Supplement.](cv273pptimsupplement.jpg)
Slide 72:
ISO TS 19091
- Lists requirements describing the details of that data
-
Deployments that conform to ISO 19091 would build to the same requirements - helps ensure interoperability
- Functional Requirements
- Performance Requirements (WHEN)
Slide 73:
ISO TS 19091
-
Defines what specific SAE J2735 messages, data frames or data elements are used to fulfill each functional requirement in ISO TS 19091.
- SPaT
- MAP
- Basic Safety Messages
- NMEA/RTCM
- SRM/SSM
- See Module CV271 - Using the ISO TS 19091 Standard to Implement V2I Intersection Applications Introduction
Slide 74:
SAE J2945/x Family of Standards
-
SAE J2945/x Family of Standards identify the information and performance requirements for applications using SAE J2735 messages
- How often a message is sent (minimum, typical, maximum)
- Minimum quality requirements
- Each document identifies the minimum requirements or recommended practices for specific applications.
Slide 75:
SAE J2945/x Family of Standards
-
SAE J2945_2017012 - Dedicated Short Range Communications (DSRC) Systems Engineering Process Guidance for SAE J2945/x Documents and Common Design Concepts
- Also known as J2945/0, defines common requirements for connected vehicle applications
- Includes systems engineering content (Concept of Operations, requirements, message exchanges, and message content) for the family of standards
Slide 76:
SAE J2945/x Family of Standards
-
SAE J2945/A - MAP/SPaT Deployment - Intersection Operations
- Previously SAE J2945/10, contains recommended best practices on using the MAP and SPaT message content to meet operational needs.
- Currently on hold
-
SAE J2945/B - Recommended Practices for Signal Preemption Message Development
- Previously SAE J2945/11, provides reference implementations on how to provide priority and preemption at signalized intersections.
- Currently under development.
Slide 77:
NTCIP 1202 v03
-
NTCIP 1202 v03 - Object Definitions for Actuated Signal Controllers
- Standardizes the communications interface between an actuated signal controller and a center
- Published May 2019 as an update to NTCIP 1202 v02 (published 2005)
- Adds systems engineering content and accommodates new user needs
Slide 78:
NTCIP 1202 v03
![The slide entitled "NTCIP 1202 v03" fully consists of a graphic. On top is an icon of a laptop labeled "Maintenance Laptop". To the left of the Maintenance Laptop is an icon of a desktop computer labeled "Traffic Management System". To the left of the Traffic Management System is an icon of a server labeled "Connected Vehicle Back Office Systems". There is a solid, bi-directional arrow between the Connected Vehicle Back Office Systems and the Traffic Management System. Below the is a box representing the Roadside Unit. There is a solid, bi-directional arrow between the Connected Vehicle Back Office Systems and the Roadside Unit. To the right of the Roadside Unit is a box representing the Controller Unit. To the right of the Controller Unit is a box representing Cabinet Subsystems. There is a solid, bi-directional arrow between the Controller Unit and the Cabinet Subsystems. The Roadside Unit is connected to the Controller Unit, Maintenance Laptop, and the Traffic Management System with dotted red lines. Additionally, the Controller Unit is directly connected to the Traffic Management System and the Maintenance Laptop with red dashed lines. Below is an icon of a modem labeled "DSRC modem". There is a solid, bi-directional arrow labeled "SAE J2735 + Modem Control" between the Roadside Unit and the DSRC Modem. At the bottom are various icons including of a car, a truck, a bus, a firetruck, a bicycle, a pedestrian with a mobile device, CCTV camera with loop detectors labelled "Vehicle Detection Subsystems", and a traffic signal with a pedestrian walk sign. The DSRC modem is connected to the car, the truck, the bus, the firetruck, the bicycle, and the pedestrian with purple dashed lines. The cabinet subsystem is connected to the truck, the bus, the firetruck, the bicycle, the pedestrian, the Vehicle Detection Subsystems, and the traffic signal with solid black lines. Communications from the truck are labelled "Freight Priority Requests". Communications from the bus are labelled "Transit Priority Requests". Communications from the firetruck are labelled "Preemption Requests". Red dashed lines represent communications subject to NTCIP 1202 or other NTCIP standards. Purple dashed lines represent communications of the DSRC interface. Solid black lines are other communications of other standards or proprietary.](cv273ppt52.jpg)
Slide 79:
NTCIP 1202 v03
-
Connected Vehicle user needs addressed by the standard
- Focus is the interface between the Roadside Unit and the controller
- Provides SPaT data to the Roadside Unit
- Provides a check that the SPaT data matches the MAP data
- Supports the entire SPaT and MAP data messages except regional extensions and start time
Slide 80:
NTCIP 1202 v03
-
Implementation Issues:
-
Does the controller push or pull data with the RSU?
- If push, should the controller push on change (when a value changes) or periodically (e.g., ten times per second)?
-
If pull, how often should the RSU request the SPaT data from the controller?
- The controller should still push periodically.
Slide 81:
NTCIP 1202 v03
-
Implementation Issues:
- Clock differential
- For additional information about NTCIP 1202 v03, see A315 modules
Slide 82:
How to Specify SPaT Messages
-
Determine what optional data elements to include in your specification
- Use ISO TS 19091 as a guideline (by use case)
-
If using NTCIP 1202 v03, complete the PRL.
- Requires some of the optional data elements in SAE J2735 to be mandatory.
-
Connected Signalized Intersections project
- Develop a standard or specification to define key capabilities to support interoperability
- Started November 2019
Slide 83:
How to Specify SPaT Messages
-
For both SPaT and MAP messages, consider the communications media
-
Dedicated Short Range Communications (DSRC)
- Would use IEEE standards, which imposes a limit of approximately 1500 bytes
- Consider latency
- Where? Range of approximate 300 meters
-
Cellular Vehicle to Anything (C-V2X)
- Release 16 expected 2020.
Slide 84:
How to Specify SPaT Messages
-
For both SPaT and MAP messages, consider security:
- Signed to indicate it's an authentic message from the source it claims to be
- Could be signed at the Roadside Unit or a center
- For additional information about security, see other PCB modules
Slide 85:
How to Specify MAP Messages
-
MAP messages must be included with SPaT messages
- Contains indexes (SignalGroupIDs) connecting SPaT movements to ingress and egress lanes
- The MAP message indicates "where the lane" is.
-
Level of Detail: Varies depending on the applications supported
- Level of resolution needed may vary
- Geographical extent needed may vary
- What information is needed (report all lanes?)
- Communications limitations (message size)
Slide 86:
How to Specify MAP Messages
- Typically only 1 to maybe 3 intersections per MAP message
-
SAE J2945/0 contains recommendations:
- Transmission rates - once every one or two seconds
- DSRC channels
- Transmission power levels
Slide 87:
How to Specify MAP Messages
-
Implementation Issues
- Must be based on WGS84 coordinate system
- Intersection ID numbering
-
Need to define consistently
- E.g., How crosswalks are represented varies around the world.
-
Creation of a Guidance Document for MAP Preparation project
- Develop a guidance document on how to create MAP messages
- Expected start date March 2020
Slide 88:
How to Specify MAP Messages
-
Tools for Developing MAP messages
- USDOT J2735 MAP Tool
- Can automate map data validation and visualize data to reduce errors
![The slide entitled "How to specify MAP messages" has a graphic on the right showing a screenshot of the USDOT J2735 MAP tool. The screenshot shows an aerial view of a neighborhood with apartment buildings and streets. On the upper right is a menu where there are options to toggle view of Lanes, Approaches, and Reference Point. Additionally, there is an option to toggle lane widths. On the left is a placeholder graphic of a gear with a wrench, indicating that the slide is about a tool.](cv273ppt53.jpg)
![Tools/Applications icon. An industry-specific item a person would use to accomplish a specific task, and applying that tool to fit your need.](cv273pptimtools.jpg)
Slide 89:
Additional References
- See Student Supplement
-
ITS Professional Capacity Building Program
-
National Operations Center of Excellence
-
USDOT Connected Vehicle Pilots
![Tools/Applications icon. An industry-specific item a person would use to accomplish a specific task, and applying that tool to fit your need.](cv273pptimtools.jpg)
Slide 90:
![This slide contains a graphic with the word "Case Study" in large letters. A placeholder graphic of a traffic control center indicating that a real-world case study follows.](cv273ppt56.jpg)
Slide 91:
Case Study: City of Anaheim
-
Deployed OBUs and RSUs from 3 different vendors
- OBUs and RSUs from the same vendor worked
-
A side-by--side comparison of applications on the different OBUs showed different results
- Times to change may be different
- Applications did not always work
- Some applications were expecting optional data elements and did not properly display if the optional data elements were not provided
Slide 92:
Case Study: City of Anaheim
-
Lessons Learned
-
MAP configuration affected the application on the OBU
- Some applications were expecting optional data elements and did not properly display if the optional data elements were not provided
- Applications were not properly handling unexpected or non-conforming data packets
- Specify which optional elements are mandatory
- Test applications to handle unexpected or non-conforming data packets
Slide 93:
![Activity Placeholder: This slide has the word “Activity” in large letters at the top of the slide, with a graphic of a hand on a computer keyboard below it.](cv273ppt57.jpg)
Slide 94:
Question
When broadcasting SPaT and MAP messages, which of the following issues must be considered?
Answer Choices
- Only one intersection is contained in each SPaT and MAP message
- All MAP messages must be accompanied by a SPaT message
- Other standards may limit the number of bytes in a message
- SPaT and MAP messages must use the same broadcast rate
Slide 95:
Review of Answers
a) Only one intersection is contained in each SPaT and MAP message
Incorrect. Each SPaT and MAP message may describe up to 32 intersections
b) All MAP messages must be accompanied by a SPaT message
Incorrect. However, SPaT messages should be accompanied by a MAP message
c) Other standards may limit the number of bytes in a message
Correct! Other standards may impose message size limitations
d) SPaT and MAP messages must use the same broadcast rate
Incorrect. For example, SPaT messages are dynamic and may need to be broadcasted more frequently
Slide 96:
Module Summary
- Describe the scope of the SAE J2735 Standard
- Describe the SPaT Message
- Describe the MAP Message
- Implementation Considerations
Slide 97:
Thank you for completing this module.
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