WGU D779 SJN1 Task 1 – CityLink
Transportation App
PART A: CITYLINK TRANSPORTATION
APPLICATION
Impact Analysis
WGU D779 – Software Product Design and Requirement Engineering
Assessment Code: SJN1
Document: Task 1 – Impact Analysis
Version: 1.0 | October 2026
Status: Original scenario-based technical analysis
1. Executive Summary
CityLink is an established public transportation mobile application serving approximately
500,000 active users in a large metropolitan area. The platform provides essential transportation
services, including bus and train schedules, ticket purchasing, real-time vehicle information, and
service disruption notifications.
The existing application uses React Native for its mobile interface, Node.js for backend services,
REST APIs for communication, OAuth2 for authentication, and PostgreSQL for data storage.
These technologies support its existing operations, but the application must now accommodate
additional government requirements intended to advance sustainable transportation and
accessibility.
The city government has introduced three major changes:
1. Electric vehicle integration, including electric bus identification, battery levels, charging
station locations, and energy-efficiency information.
2. Accessibility improvements, including voice navigation and wheelchair-friendly routes.
3. A carbon footprint calculator that estimates the environmental impact of journeys based
on selected transportation modes.
These requirements introduce changes across the presentation, application, integration, and data
layers. Although CityLink's existing architecture offers a foundation for additional functionality,
its database has not been optimized for large volumes of real-time data. Consequently, the
,integration of electric vehicle telemetry requires particular attention to scalability and
performance.
This analysis recommends extending the existing modular monolithic architecture rather
than immediately replacing it. The proposed approach introduces carefully separated
application modules, validated external data interfaces, appropriate caching, accessibility-
focused interface improvements, and a controlled implementation process.
The most significant risks involve incomplete external data, increased processing demands,
inaccurate accessibility information, changes to the mobile experience, and potential disruption
to existing services.
With appropriate data agreements, technical validation, stakeholder collaboration, and phased
implementation, the proposed enhancements are technically feasible. Final feasibility depends on
confirming resource availability, implementation costs, infrastructure capacity, and agreed
delivery dates.
2. Introduction and Background
2.1 Purpose of the Impact Analysis
The purpose of this document is to evaluate how the newly mandated requirements will affect
CityLink's existing software architecture, business operations, users, and supporting
infrastructure.
The analysis identifies components requiring modification, evaluates the potential technical and
operational consequences, and recommends an implementation approach that balances new
functionality with system reliability.
The objectives are to:
Establish a baseline understanding of CityLink's current application.
Identify the effects of the new requirements on the existing system.
Evaluate system integration, database, interface, security, accessibility, and performance
implications.
Identify project dependencies and implementation risks.
Prioritize the proposed changes.
Recommend appropriate mitigation and validation strategies.
Establish a traceable foundation for the Software Requirements Specification.
2.2 Existing Application
CityLink has operated for more than one year and serves as a transportation information and
ticketing platform for metropolitan passengers.
,Its existing capabilities include schedule browsing, ticket purchasing, live transport information,
disruption notifications, user accounts, and saved favorite routes.
These services are important because passengers depend on timely and accurate transportation
information when planning journeys. Ticketing functions also require reliable transaction
processing and secure handling of account information.
Any modification must therefore preserve the application's established functionality.
2.3 Current Technical Architecture
Current
Component Principal responsibility
implementation
Mobile frontend React Native Cross-platform interface for iOS and Android
Backend application Node.js Application logic and processing
Data exchange between the mobile application
Communication REST APIs
and backend
Transportation City transport authority
Schedules, routes, and delay information
integration API
Authentication OAuth2 Account authentication and authorized access
User profiles, ticket transactions, schedules,
Database PostgreSQL
and analytics
Infrastructure Cloud-hosted services Application hosting and operational scalability
CityLink uses a modular monolithic architecture. This means different logical modules can exist
within a single deployable backend application.
This structure can support the proposed requirements if the development team maintains clear
module boundaries and avoids excessive coupling between features.
However, because the existing PostgreSQL deployment is not optimized for high-volume real-
time information, the design must carefully distinguish transactional data from frequently
changing vehicle telemetry.
3. Business Problem and Need for Change
The existing CityLink application provides transportation information but does not have the
newly requested features established in the scenario.
3.1 Sustainable Transportation
The city intends to improve visibility into its electric transportation fleet.
, Passengers should be able to identify electric buses and view relevant operational information,
including battery levels, charging stations, and energy efficiency.
This creates a need for CityLink to receive, process, and display electric vehicle information that
is not established as part of the current system.
3.2 Inclusive Transportation
Transportation applications should accommodate users with varying mobility and accessibility
needs.
The proposed voice navigation capability can improve access to transportation information for
individuals who rely on auditory guidance or assistive technologies.
Wheelchair-friendly route information can help passengers identify journeys with suitable
accessibility characteristics.
However, the software must avoid representing a route as accessible unless there is sufficient
evidence supporting that classification.
3.3 Environmental Awareness
The carbon footprint calculator will help passengers understand the estimated environmental
effects of different transportation choices.
By presenting an understandable estimate, CityLink can support informed decisions without
implying that estimated emissions represent exact measurements.
The application will need an approved calculation methodology and appropriate data sources
before the calculator can produce reliable results.
4. Scope of the Proposed Changes
4.1 In-Scope Changes
Electric vehicle integration
Identify electric buses within transportation listings.
Retrieve and display battery-level information when available.
Display charging station locations.
Present energy-efficiency information.
Handle missing, invalid, or outdated telemetry.
Modify supporting backend interfaces and data processing.
Accessibility improvements
Transportation App
PART A: CITYLINK TRANSPORTATION
APPLICATION
Impact Analysis
WGU D779 – Software Product Design and Requirement Engineering
Assessment Code: SJN1
Document: Task 1 – Impact Analysis
Version: 1.0 | October 2026
Status: Original scenario-based technical analysis
1. Executive Summary
CityLink is an established public transportation mobile application serving approximately
500,000 active users in a large metropolitan area. The platform provides essential transportation
services, including bus and train schedules, ticket purchasing, real-time vehicle information, and
service disruption notifications.
The existing application uses React Native for its mobile interface, Node.js for backend services,
REST APIs for communication, OAuth2 for authentication, and PostgreSQL for data storage.
These technologies support its existing operations, but the application must now accommodate
additional government requirements intended to advance sustainable transportation and
accessibility.
The city government has introduced three major changes:
1. Electric vehicle integration, including electric bus identification, battery levels, charging
station locations, and energy-efficiency information.
2. Accessibility improvements, including voice navigation and wheelchair-friendly routes.
3. A carbon footprint calculator that estimates the environmental impact of journeys based
on selected transportation modes.
These requirements introduce changes across the presentation, application, integration, and data
layers. Although CityLink's existing architecture offers a foundation for additional functionality,
its database has not been optimized for large volumes of real-time data. Consequently, the
,integration of electric vehicle telemetry requires particular attention to scalability and
performance.
This analysis recommends extending the existing modular monolithic architecture rather
than immediately replacing it. The proposed approach introduces carefully separated
application modules, validated external data interfaces, appropriate caching, accessibility-
focused interface improvements, and a controlled implementation process.
The most significant risks involve incomplete external data, increased processing demands,
inaccurate accessibility information, changes to the mobile experience, and potential disruption
to existing services.
With appropriate data agreements, technical validation, stakeholder collaboration, and phased
implementation, the proposed enhancements are technically feasible. Final feasibility depends on
confirming resource availability, implementation costs, infrastructure capacity, and agreed
delivery dates.
2. Introduction and Background
2.1 Purpose of the Impact Analysis
The purpose of this document is to evaluate how the newly mandated requirements will affect
CityLink's existing software architecture, business operations, users, and supporting
infrastructure.
The analysis identifies components requiring modification, evaluates the potential technical and
operational consequences, and recommends an implementation approach that balances new
functionality with system reliability.
The objectives are to:
Establish a baseline understanding of CityLink's current application.
Identify the effects of the new requirements on the existing system.
Evaluate system integration, database, interface, security, accessibility, and performance
implications.
Identify project dependencies and implementation risks.
Prioritize the proposed changes.
Recommend appropriate mitigation and validation strategies.
Establish a traceable foundation for the Software Requirements Specification.
2.2 Existing Application
CityLink has operated for more than one year and serves as a transportation information and
ticketing platform for metropolitan passengers.
,Its existing capabilities include schedule browsing, ticket purchasing, live transport information,
disruption notifications, user accounts, and saved favorite routes.
These services are important because passengers depend on timely and accurate transportation
information when planning journeys. Ticketing functions also require reliable transaction
processing and secure handling of account information.
Any modification must therefore preserve the application's established functionality.
2.3 Current Technical Architecture
Current
Component Principal responsibility
implementation
Mobile frontend React Native Cross-platform interface for iOS and Android
Backend application Node.js Application logic and processing
Data exchange between the mobile application
Communication REST APIs
and backend
Transportation City transport authority
Schedules, routes, and delay information
integration API
Authentication OAuth2 Account authentication and authorized access
User profiles, ticket transactions, schedules,
Database PostgreSQL
and analytics
Infrastructure Cloud-hosted services Application hosting and operational scalability
CityLink uses a modular monolithic architecture. This means different logical modules can exist
within a single deployable backend application.
This structure can support the proposed requirements if the development team maintains clear
module boundaries and avoids excessive coupling between features.
However, because the existing PostgreSQL deployment is not optimized for high-volume real-
time information, the design must carefully distinguish transactional data from frequently
changing vehicle telemetry.
3. Business Problem and Need for Change
The existing CityLink application provides transportation information but does not have the
newly requested features established in the scenario.
3.1 Sustainable Transportation
The city intends to improve visibility into its electric transportation fleet.
, Passengers should be able to identify electric buses and view relevant operational information,
including battery levels, charging stations, and energy efficiency.
This creates a need for CityLink to receive, process, and display electric vehicle information that
is not established as part of the current system.
3.2 Inclusive Transportation
Transportation applications should accommodate users with varying mobility and accessibility
needs.
The proposed voice navigation capability can improve access to transportation information for
individuals who rely on auditory guidance or assistive technologies.
Wheelchair-friendly route information can help passengers identify journeys with suitable
accessibility characteristics.
However, the software must avoid representing a route as accessible unless there is sufficient
evidence supporting that classification.
3.3 Environmental Awareness
The carbon footprint calculator will help passengers understand the estimated environmental
effects of different transportation choices.
By presenting an understandable estimate, CityLink can support informed decisions without
implying that estimated emissions represent exact measurements.
The application will need an approved calculation methodology and appropriate data sources
before the calculator can produce reliable results.
4. Scope of the Proposed Changes
4.1 In-Scope Changes
Electric vehicle integration
Identify electric buses within transportation listings.
Retrieve and display battery-level information when available.
Display charging station locations.
Present energy-efficiency information.
Handle missing, invalid, or outdated telemetry.
Modify supporting backend interfaces and data processing.
Accessibility improvements
