opentripplanner/OpenTripPlanner
Jan 2026 – Jun 2026
6 Months active
Languages Used
JavaGraphQLMarkdown
Technical Skills
Javabackend developmentrouting algorithmstest-driven developmentunit testingAPI development
Håkon Bliksås Carlsen
PROFILE
Håkon Bliksås Carlsen
Over six months, contributed to the opentripplanner/OpenTripPlanner repository by designing and refining carpool routing features, focusing on routing accuracy, itinerary flexibility, and system maintainability. Developed and integrated new access modes, enhanced timing calculations, and implemented per-stop deviation budgets to improve user experience and trip matching. Applied Java and GraphQL to expand API capabilities, optimize algorithms, and ensure robust data validation. Refactored core models and improved test infrastructure, enabling more reliable deployments and scalable service management. Emphasized backend development, error handling, and test-driven development, resulting in higher data integrity, better performance, and streamlined quality assurance for carpooling workflows.
Overall Statistics
Feature vs Bugs
92%Features
Repository Contributions
69Total
Bugs
2
Commits
69
Features
22
Lines of code
16,917
Activity Months6
Your Network
66 peopleSame Organization
@entur.org10
Shared Repositories
56
Work History
June 2026
11 Commits • 4 Features
Jun 1, 2026June 2026 monthly summary for opentripplanner/OpenTripPlanner focused on carpool enhancements, data quality, service scalability, and testing improvements. Key outcomes include improved routing accuracy and performance for carpool itineraries, stronger data integrity and validation for carpool trips, scalable service management with multi-SIRI support and purging of expired trips, and a strengthened testing foundation to boost QA efficiency. Technologies demonstrated include A* routing, beeline-based time estimates, SIRI integration, and test infrastructure development.
11 Commits • 4 Features
Jun 1, 2026June 2026 monthly summary for opentripplanner/OpenTripPlanner focused on carpool enhancements, data quality, service scalability, and testing improvements. Key outcomes include improved routing accuracy and performance for carpool itineraries, stronger data integrity and validation for carpool trips, scalable service management with multi-SIRI support and purging of expired trips, and a strengthened testing foundation to boost QA efficiency. Technologies demonstrated include A* routing, beeline-based time estimates, SIRI integration, and test infrastructure development.
June 2026
May 2026
12 Commits • 4 Features
May 1, 2026May 2026 monthly summary for OpenTripPlanner (opentripplanner/OpenTripPlanner) focused on carpool enhancements and reliability improvements across the core carpooling workflow. Key features delivered include cost/weight optimization for carpool routing, integration of walking segments into carpool itineraries, booking information enrichment and URL parameterization, and strengthened request filtering/validation. These changes collectively improved route quality, user experience, and operational reliability while preserving compatibility with existing itineraries and booking flows.
May 2026
12 Commits • 4 Features
May 1, 2026May 2026 monthly summary for OpenTripPlanner (opentripplanner/OpenTripPlanner) focused on carpool enhancements and reliability improvements across the core carpooling workflow. Key features delivered include cost/weight optimization for carpool routing, integration of walking segments into carpool itineraries, booking information enrichment and URL parameterization, and strengthened request filtering/validation. These changes collectively improved route quality, user experience, and operational reliability while preserving compatibility with existing itineraries and booking flows.
April 2026
17 Commits • 2 Features
Apr 1, 2026April 2026 monthly summary for opentripplanner/OpenTripPlanner focusing on carpooling enhancements and core model refactoring to improve user value, matching flexibility, and maintainability. Implemented per-stop deviation budgets, enhanced timing calculations including boarding time integration and pickup-time-based intermediate stops, and broadened itinerary options by removing directional constraints and limiting logic. Completed substantial core model refactoring to simplify architecture, centralize constants, and improve test stability, with accompanying fixes to rounding-related timing paths and geometry usage.
17 Commits • 2 Features
Apr 1, 2026April 2026 monthly summary for opentripplanner/OpenTripPlanner focusing on carpooling enhancements and core model refactoring to improve user value, matching flexibility, and maintainability. Implemented per-stop deviation budgets, enhanced timing calculations including boarding time integration and pickup-time-based intermediate stops, and broadened itinerary options by removing directional constraints and limiting logic. Completed substantial core model refactoring to simplify architecture, centralize constants, and improve test stability, with accompanying fixes to rounding-related timing paths and geometry usage.
April 2026
March 2026
23 Commits • 10 Features
Mar 1, 2026March 2026 (2026-03) performance summary for opentripplanner/OpenTripPlanner focused on carpooling and last-mile integration with walking-first itineraries. Key efforts centered on refactoring for maintainability, expanding street-mode support, and improving data fidelity and test quality to deliver more accurate, performance-conscious itineraries with greater business value.
March 2026
23 Commits • 10 Features
Mar 1, 2026March 2026 (2026-03) performance summary for opentripplanner/OpenTripPlanner focused on carpooling and last-mile integration with walking-first itineraries. Key efforts centered on refactoring for maintainability, expanding street-mode support, and improving data fidelity and test quality to deliver more accurate, performance-conscious itineraries with greater business value.
February 2026
4 Commits • 1 Features
Feb 1, 2026February 2026: Delivered Carpooling Routing Support as a new access/egress mode in the OpenTripPlanner routing framework, with new classes and methods, integrated into the routing pipeline, and supported by test coverage, documentation updates, and schema changes. This enhances multimodal routing options, enabling higher user flexibility and potential adoption of carpooling features, contributing to sustainability goals and system maintainability.
4 Commits • 1 Features
Feb 1, 2026February 2026: Delivered Carpooling Routing Support as a new access/egress mode in the OpenTripPlanner routing framework, with new classes and methods, integrated into the routing pipeline, and supported by test coverage, documentation updates, and schema changes. This enhances multimodal routing options, enabling higher user flexibility and potential adoption of carpooling features, contributing to sustainability goals and system maintainability.
February 2026
January 2026
2 Commits • 1 Features
Jan 1, 2026January 2026 focused on enhancing carpool routing accuracy and reinforcing test reliability for the opentripplanner/OpenTripPlanner project. Key deliverable: Carpool Routing Duration Enhancement, which refactors duration calculation for multi-stop carpools to use the origin-to-destination duration instead of the baseline, improving routing precision and user experience (commit 33001d88b68276d699df7ba156f89077eb0607e9). Major bug fix: InsertionEvaluatorTest was refactored to use deterministic routing functions, ensuring identical outputs for identical inputs and boosting test reliability (commit ad6174dfa8d84c4ad5842a1cdc297458ae4287c5). Overall impact: higher quality carpool routing and more stable CI, enabling faster iteration and safer deployments. Technologies/skills demonstrated: Java, routing algorithm refinement, unit/integration testing, test determinism, and commit traceability.
January 2026
2 Commits • 1 Features
Jan 1, 2026January 2026 focused on enhancing carpool routing accuracy and reinforcing test reliability for the opentripplanner/OpenTripPlanner project. Key deliverable: Carpool Routing Duration Enhancement, which refactors duration calculation for multi-stop carpools to use the origin-to-destination duration instead of the baseline, improving routing precision and user experience (commit 33001d88b68276d699df7ba156f89077eb0607e9). Major bug fix: InsertionEvaluatorTest was refactored to use deterministic routing functions, ensuring identical outputs for identical inputs and boosting test reliability (commit ad6174dfa8d84c4ad5842a1cdc297458ae4287c5). Overall impact: higher quality carpool routing and more stable CI, enabling faster iteration and safer deployments. Technologies/skills demonstrated: Java, routing algorithm refinement, unit/integration testing, test determinism, and commit traceability.
Activity
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Quality Metrics
Correctness91.8%
Maintainability87.0%
Architecture88.4%
Performance86.6%
AI Usage22.2%
Skills & Technologies
Programming Languages
GraphQLJavaMarkdown
Technical Skills
API DevelopmentAPI IntegrationAPI developmentAPI integrationAlgorithm DesignAlgorithm OptimizationBackend DevelopmentCode RefactoringData MappingGraph TheoryGraphQLJavaRouting AlgorithmsSoftware ArchitectureSoftware Design
Repositories Contributed To
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