Module 14 - A311b
A311b: Specifying Requirements for DMS Systems Based on NTCIP 1203 Standard v03
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A311b: Specifying User Needs for DMS Systems Based on NTCIP 1203 Standard
Table of Contents
1. Module Description
Dynamic Message Signs (DMSs) are field devices deployed as part of a central Freeway Management System's information dissemination purposes, and remotely monitored and controlled. The NTCIP 1203 standard v03 was developed using Systems Engineering Process (SEP) and was published in two companion volumes: Part 1 Main standard contains user needs, requirements and design content, including PRL, and Part 2 contains Annex C Test Procedures (previous versions did not contain test procedures). Agencies prepare their DMS project specification based on the information provided by the standard to acquire standard-based interoperable signs. Participants will learn how to specify requirements and prepare a project level Requirements Traceability Matrix (RTM) necessary for DMS procurement specification.
DMS Training Modules
Agencies preparing a DMS project specification for Dynamic Message signs (DMS) based on NTCIP 1203 v03 are advised to consult the following three updated sequential modules to complete the DMS related training:
The purpose of this updated module is to incorporate necessary changes made by the updated NTCIP Standard v03 (from v02), and assists technical staff in writing unambiguous, complete, and well-written user needs based on NTCIP 1213 Standard v03. This module provides participants with information on how to identify the appropriate use of the NTCIP 1213 Standard v03 and acquire a DMS system based on what the user is seeking to accomplish; and also provides participants with information on how to identify user needs that can be traced to requirements, which will be discussed in A306b: Specifying Requirements for DMS Systems based on NTCIP 1213 Standard v03, with support from tools and resources such as Requirements Traceability Matrix (RTM) and Protocol Requirements List (PRL) in following a Systems Engineering (SE) Process. An updated final module, T311, will deal with the preparing and applying of testing documentation for DMS based on NTCIP 1203 Standard v03.
The module focuses on the DMS communications interface aspects—how to configure, monitor, and control DMSs remotely from a Transportation Management Center (TMC)-Management Station-or locally at the front-panel of a DMS controller—using data objects provided by the NTCIP 1203 v03 Standard Management Information Base (MIB).
3. About NTCIP 1203 v03
As for limitations, NTCIP 1203 v03 defines the data that could be transmitted between a central system and a conformant DMS, but it does not define the functionalities and functions available within a DMS or a central system. Also, NTCIP 1203 v03 does not claim to address all potential capabilities of a DMS or a controlling/monitoring Central System; if NTCIP 1203 v03 would make this claim, no progress could be made (e.g., if NTCIP 1203 v03 would not allow for the possibility of defining extensions, no additional functionalities could be added, by either NTCIP 1203 v03 itself or by vendors or agencies).
It is also of utmost importance for the reader to understand that not all of the functionalities have to be supported by a DMS (or a Central System) to claim conformance. Instead, the project-specific specifications that do reference and incorporate desired applicable functionalities from NTCIP 1203 v03 (also sometimes represented as NTCIP 1203v3) are the guiding requirements that determine compliance.
How NTCIP 1203 v03 is Organized (Sections)
NTCIP 1203 v03 contains the following main sections, each building on the previous section(s):
Section 1 - Overview - This section provides the user with references, table of contents, glossary, and other information.
Section 2 - Concept of Operations - This section provides a description of user needs (needs for features and needs related to the operational environment) applicable to DMS systems.
Section 3 - Functional Requirements - This section defines the functional requirements that address the user needs identified in the Concept of Operations. It includes a Profiles Requirements List (PRL) Table that defines conformance requirements thereby allowing users to select the desired options for a particular project. An additional table identifies supplemental requirements that show requirements that are used more than once by different main functional requirements. A third table identifies the supplemental requirements for the MULTI tags and provides an indication of the functional requirement that a particular MULTI tag fulfills.
Section 4 - Dialogs and Interface Specifications - This section describes how each functional requirement is fulfilled. The dialogs define the standardized procedures for a central system to manage a sign. The interface specifications define the operations that are allowed by the sign and how data elements are inter-related.
Section 5 - Management Information Base - This section defines the data elements (object definitions) exchanged during communications (an update of NTCIP 1203:1997 Section 2).
Section 6 - Mark-Up Language for Transportation Information (MULTI) - This section defines the language used to communicate to the sign how a message is to be displayed. Similar to HTML, tags are included to specify the attributes of a message and how it is displayed on a sign (an update of NTCIP 1203:1997 Section 3).
Section 7 - Test Procedures - This section is currently left empty until guidance from another NTCIP working group has been received. This group, called the Technical Coordination Forum (TCF), defines the guidelines for the test procedures that are applicable to all technical WGs within the NTCIP community.
Annex A - Requirements Traceability Matrix - This annex provides two tables. The first table traces each requirement to a dialog, one or more interfaces, and its associated list of objects. The second table identifies supplemental traces for requirements that are used more than once for various requirements.
Guidance on Use of Sections
NTCIP 1203 v03 has been designed for different audiences.
4. DMS Functional Requirements
The Protocol Requirements List (PRL) - A Functional Requirement is a requirement of a given function and therefore is only required to be implemented if the associated functionality (e.g., user need) is selected through the use of the Protocol Requirements List (PRL).
The PRL also indicates which of the items are mandatory, conditional, or optional. The PRL can be used by procurement personnel to specify the desired features of a DMS or can be used by a manufacturer to document the features supported by their implementation.
Types of DMS Requirements
The functional requirements are presented in three broad categories as follows:
For example, they include requirements related to the content of the message to be displayed on a DMS, which may be a supplemental requirement to activating a message, defining a message, etc.
Requirements Traceability Matrix (RTM) Examples
What is RTM?
The RTM is a table that links the Functional Requirements as presented in Section 3 with the corresponding Dialogs (Section 4.2) on the same (gray) line. Each Functional Requirement/Dialog relates/uses one or more groups of Objects. The Objects (also known as Data Elements) are listed to the side; the formal definition of each object is contained within Section 5. Using this table, each Functional Requirement can thus be traced in a standardized way.
The audience for this table is implementers (vendors and central system developers) and conformance testers. Additionally, other interested parties might use this table to determine how particular functions are to be implemented using the standardized dialogs, interfaces, and object definitions. The following figure explains value of RTM.
(Extended Text Description: Author's relevant description: Value of Design Content Provided by the RTM. This figure makes key points on value-added content of an RTM. Use of an RTM leads to conformant Interface. An image of a Management Station is shown connected to DMS sign controller which in turn connects to a DMS sign. An arrow points to the connection with the text DMS Communications Interface, with the following bullet items. The word Interface from the first bullet points to the image:
To conform to a Functional Requirement, a DMS shall implement all Objects and Dialogs traced from that Functional Requirement; a Management Station shall implement all Dialogs traced fromthe Functional Requirement. In order to be consistent with a Functional Requirement, a Management Station shall be able to fulfill the Functional Requirement using only Objects and Dialogs that a conforming DMS is required to support.
Conformance: Meets a specified standard
Examples of Partially Completed RTM
Requirements Traceability Matrix (RTM)-Annex A
Example entries in rows traces DMS requirement called Identify DMS,: Traces to Dialogs G.1 and objects 5.2.2 and 5.2.9.
Agency does: NOT try to figure out the design, RTM provides that.
(Extended Text Description: Author's relevant description: Single Message is referenced with Generic G.1, G.2 and G.3 Dialogs. The Requirements Traceability Matrix (RTM) presented in Annex A identifies the standardized dialog that can be used to achieve each of the data exchange requirements defined in Section 3.5. Simple data exchange requirements reference one of the generic SNMP dialogs along with a list of data elements. These equate to a single message being sent (e.g., a GET request) containing the referenced data elements followed the appropriate response per the generic dialog specification. Single message dialog is shown with arrow to G1 in RTM and objects from bottom text box, to the following table:
(Extended Text Description: Author's relevant description: SPECIFIED DIALOGS-This section provides the standardized data exchange sequences that can be used by management stations to ensure interoperable implementations for the various data exchange requirements identified in Section 3.4. Diagrams and graphical representations are included to supplement the text (i.e., not used as a replacement for the text). This section only includes dialogs that have special semantics or impose special restrictions on the operations that are allowed. Example: RTM is shown with Dialog 126.96.36.199 with an arrow pointing in RTM with associated objects in the following table:
Dialog 188.8.131.52 fulfils the requirement using these objects.)
(Extended Text Description: Table shown with the Functional Requirement in the first two rows pointing to their corresponding Objects:
The Requirements Traceability Matrix (RTM) presented in Annex A identifies the standardized dialog that can be used to achieve each of the data exchange requirements defined in Section 3.5. Simple data exchange requirements reference one of the generic SNMP dialogs along with a list of data elements (see Annex G). These equate to a single message being sent (e.g., a GET request) containing the referenced data elements followed the appropriate response per the generic dialog specification.
The dialogs may also be accompanied by an informative figure that provides a graphical depiction of the normative text. The figures conform to the Unified Modeling Language and depict the management station as an outside actor sending a series of messages to the device and the device returning responses. If there is any conflict between the figure and the text, the text takes precedence.
The following figure provides a detailed UML depiction of Activating a Message of DMS.
(Extended Text Description: Author's relevant description: Example of a detailed UML (Unified Modeling Language) depiction of Activating a Message of DMS, with the management station on the upper left and the DMS on the right. The precondition states: The management station shall ensure that the desired message is supported by the DMS. This may entail downloading the desired message contents to the DMS. The UML diagram describes the behavior between the objects in the system.)
5. Reference to Standards
7. References for Additional Information
8. Study Questions
1. Which of the following is a FALSE statement related to the DMS Standard?
2. Which of the following is a FALSE statement as it is applied to DMS?
3. Which of the following statements does NOT apply to RTM?
4. Which of the following is a False Statement related to a DMS specification?
9. Icon Guide
The following icons are used throughout the module to visually indicate the corresponding learning concept listed below, and/or to highlight a specific point in the training material.
1) Background information: General knowledge that is available elsewhere and is outside the module being presented. This will be used primarily in the beginning of the slide set when reviewing information readers are expected to already know.
2) Tools/Applications: An industry-specific item a person would use to accomplish a specific task, and application of that tool to fit the need.
3) Remember: Used when referencing something already discussed in the module that is necessary to recount.
4) Refer to Student Supplement: Items or information that are further explained/detailed in the Student Supplement.
5) Example: Can be real-world (case study), hypothetical, a sample of a table, etc.
6) Checklist: Used to indicate a process that is being laid out sequentially.