BSM (Basic Safety Messages)

BSM Fundamentals: (October 2012 - https://www.its.dot.gov/itspac/october2012/PDF/data_availability.pdf)

• Connected V2V safety applications are built around the SAE J2735 BSM, which has two parts 
  • BSM Part 1: 
    • Contains the core data elements (vehicle size, position, speed, heading acceleration, brake system status)
    • Transmitted approximately 10x per second 
  • BSM Part 2: 
    • Added to part 1 depending upon events (e.g., ABS activated) 
    • Contains a variable set of data elements drawn from many optional data elements (availability by vehicle model varies) 
    • Transmitted less frequently
  • No on-vehicle BSM storage of BSM data 
  • The BSM is transmitted over DSRC (range ~1,000 meters) 
• The BSM is tailored for low latency, localized broadcast required by V2V safety applications

Areas of Concern:

• BSM Part one does not include a direct timestamp that identifies the time at which the message was captured. Its contains an offset, but that only represents a period in which the time has been valid.

VSD Conversation:

Reasons to package BSM into VSD within ODE:

• Increase performance:
• Moves processing and aggregation away from RSU and other data aggregators into centralized data hubs.

• Standardize inputs into the ODE:
• Any standards changes can be addressed at ODE instead of all Black Boxes
• VSD is a SDC standard, not J2735

• ODE community can deposit data to SDC utilizing existing RSU WSMP forwarding mechanisms. 
• The ODE should be able to receive WSMP forwarded BSMs as a general input would be a great addition to the ODE and this input would have the same capabilities as uploading BSMs through the user web interface or the monitored upload directory.  
• Providing local DOT with access to data
• ODE has access to BSM data, not just VSD data (filtering, aggregation, etc.)
• Users of the ODE have multiple options to receive BSMs, and they have the flexibility to decide on outputs to other systems, internal or external

VSD Details (Outdated 2014):

Vehicle Situation Data messages (VSM) are sent to the Local Current Situation Data Warehouse (LCSDW) where they are distributed to Situation Data Processing Centers to be aggregated and processed. Information from processed VSMs can be used to assess traffic patterns, traffic flow, weather conditions, etc. in a given geographic area. This information is then passed along to infrastructure users (Traffic Management Centers, etc.) for use in traffic operations, management, and planning and to downstream vehicles to enable drivers to make informed decision regarding their travel route. This document defines all of the Data Frames (DF) and Data Elements (DE) contained in the VSM and provides guidance as to when individual data records should be recorded and when VSMs should be generated and transmitted to the LCSDW.