Initiating the Systems Engineering Process for Rural Connected Vehicle Corridors, Volume 3: Model System Requirements Specification (2021)

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1   is preface, normally not included in a System Requirements Specication (SyRS) document, introduces background topics that set the tone for this model SyRS. • Background: NCHRP Project 08-120, “Initiating the Systems Engineering Process for Rural Connected Vehicle Corridors” State and local transportation agencies are preparing their infrastructure for the integration of connected vehicles. To date, most connected vehicle research has focused on applica- tions in urban areas, but agencies also need long-term planning to assess resource needs required for deploying, operating, and maintaining connected vehicle infrastructure on rural corridors. Rural corridors oen include (1) long stretches of highway with limited power, communications, and intelligent transportation systems (ITS) infrastructure; (2) long distances between cities or services for travelers; (3) dierent trac and roadway characteristics (e.g., higher posted speed limits, higher percentage of truck volume, and roadway geometry); and (4) signicant incident-related rerouting distances. Connected vehicle deployments in rural areas present opportunities for potential improvements in safety, mobility, and eciency. erefore, it is important for the agencies that operate and maintain rural corridors to have a vision for connected vehicle deployment. e objectives of this research are to identify (1) connected vehicle applications that will be most relevant on rural corridors; (2) scalable ways connected vehicles may be integrated into transportation agencies’ trac operations and management plans; (3) connected vehicles and cyber-physical infrastructure requirements within rural corridors; (4) the anticipated roles and responsibilities of agencies in authorizing, deploying, operating, and maintaining ITS and other transportation systems management and operations (TSMO) technologies within rural corridors; and (5) the related stang and resource needs. is research project used a systems engineering approach to develop a model Concept of Operations (ConOps) and a SyRS to guide agencies responsible for rural corridors as they begin to assess their needs, operational concepts, scenarios, and requirements for connected vehicle deployment. • How to Use the Document is document is a model SyRS, meaning it contains information that will apply in general to most current and proposed systems, and it is intended to be a starting point for P R E F A C E Initiating the Systems Engineering Process for Rural Connected Vehicle Corridors, Volume 3: Model System Requirements Specification

2 Initiating the Systems Engineering Process for Rural Connected Vehicle Corridors deployers. It addresses the core, common priorities and provides a base document that a deploying agency can customize to t their project and situation. It is not written for a specic implementation and does not address a transportation agency’s unique operations and system management. To assist the reader in tailoring this model SyRS, the project team is using callout boxes labeled Note to reader (see the following example) to dierentiate between “model SyRS text” versus “how to adapt the text.” Note to reader: The key sections of this SyRS are Section 3, System Requirements; Section 4, System Interface Requirements; and Appendix, Needs-to-Requirements Traceability Matrix. • High-Level Overview of the Systems Engineering Process and the Role of the ConOps in the Systems Engineering Lifecycle Process Systems engineering is an interdisciplinary approach and a means to enable a successful system that focuses on the entire system lifecycle (see Figure 1). Customer needs and required functionality are dened early in the development stage. Requirements are documented, followed by design synthesis and system validation while considering the complete problem: operations, cost and schedule, performance, training and support, test, manufacturing, and disposal. e SyRS is the key document in which the technical details for a project are formed. is document takes the user needs from the ConOps and breaks them down into more detailed and specic requirements specifying what the system (or subsystem) has to do specically, without specifying how the system has to do it. As an example, a user need may (Source: FHWA Systems Engineering for Intelligent Transportation Systems, January 2007.) Figure 1. Systems engineering “Vee” diagram.

Preface 3   be that transportation operators need to collect, fuse, and analyze traffic management data. That user need would then be broken down into multiple requirements stating what specific types of traffic management data need to be collected, what sources that data needs to be collected from, and what sources of data need to be fused for analysis. The key purpose of the SyRS is to provide the specific technical requirements for the system in enough detail for the system developers and designers to design the system without constraining those designs to specific solutions and technologies. If existing system constraints require the use of specific technologies, that is acceptable; however, the goal should be to provide the system designers and developers maximum flexibility in devel- oping technical solutions. An important aspect of the SyRS is maintaining user needs-to- requirements traceability. Every user need in the ConOps should have at least one system requirement that addresses that need. Conversely, there should be no system require- ments that do not trace to at least one user need. During the SyRS development process, if a requirement is identified that cannot be logically traced to an existing user need, this should prompt a review of the ConOps to determine whether a new user need should be developed or whether the requirement is necessary.