Previous Chapter: References
Suggested Citation: "Glossary of Key Terms." National Academies of Sciences, Engineering, and Medicine. 2024. Implementing Machine Learning at State Departments of Transportation: A Guide. Washington, DC: The National Academies Press. doi: 10.17226/27880.

Glossary of Key Terms

Term Definition
Autoencoders A type of neural network used for unsupervised learning, particularly effective in dimensionality reduction and feature learning.
Classification A common type of ML task where the goal is to assign a category or label to the input data (e.g., vehicle, pedestrian, stop sign).
Computer vision A field of artificial intelligence that focuses on enabling computers to interpret and understand visual information such as images and videos.
Convolutional Neural Network A type of deep learning model particularly effective for image and video processing, known for automatically learning salient features.
Deep learning (DL) A subset of ML models that uses a neural network with multiple layers.
Feature engineering Selecting, transforming, and creating features from raw data to improve the performance of models. For example, transforming the time of day in hours-minutes-seconds into something discrete like morning peak period, afternoon peak period, and others could be informative for an ML task.
Fine-tuning The process of making small adjustments to a pre-trained model to better fit to a specific task.
Ground truth The correct labeled data which are used to evaluate the performance of ML models.
Hyperparameters Settings or configurations in ML models, such as the depth of decision trees or learning rate in neural networks, that are not learned from the data but set before the training process.
Label A tag or category assigned to data such as its class.
Machine learning (ML) A subset of artificial intelligence which involves training models to learn from data and make predictions without being explicitly programmed.
Suggested Citation: "Glossary of Key Terms." National Academies of Sciences, Engineering, and Medicine. 2024. Implementing Machine Learning at State Departments of Transportation: A Guide. Washington, DC: The National Academies Press. doi: 10.17226/27880.
Term Definition
Model validation The process of testing an ML model with new, unseen data to evaluate its performance.
Natural language processing (NLP) A field of artificial intelligence that focuses on the interaction between computers and human language. It includes tasks such as text analysis, sentiment analysis, and language generation.
Object recognition The process of recognizing and categorizing objects in images or videos.
Personally Identifiable Information (PII) Any information that can be used to identify an individual, either directly or indirectly. PII can be stored in electronic, paper, or other media.
Pipeline A series of data processing steps often used to train models to make predictions.
Pre-trained model A model that has been trained on a large and often general dataset that can be used as a starting point for a more specific task.
Principal Component Analysis (PCA) A technique used to reduce the dimensionality of data, emphasizing variation and capturing strong patterns.
Reinforcement learning (RL) A type of ML in which an agent interacts with an environment and tries to maximize a reward function.
Semantic segmentation The process of categorizing each pixel in an image or video with a label.
Semi-supervised learning This type of ML practice combines elements of both supervised and unsupervised learning, typically using a small set of labeled data with a larger amount of unlabeled data.
Structured data Formatted and organized data with a defined schema, such as tabular data.
Supervised learning An ML strategy where the model is trained using only labeled data.
Unstructured data Data lacking a specific format or organization, such as text, images, or audio.
Unsupervised learning An ML strategy where the model is trained on unlabeled data. Clustering, dimensionality reduction, and anomaly detection are common examples of unsupervised learning techniques.
Suggested Citation: "Glossary of Key Terms." National Academies of Sciences, Engineering, and Medicine. 2024. Implementing Machine Learning at State Departments of Transportation: A Guide. Washington, DC: The National Academies Press. doi: 10.17226/27880.

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Suggested Citation: "Glossary of Key Terms." National Academies of Sciences, Engineering, and Medicine. 2024. Implementing Machine Learning at State Departments of Transportation: A Guide. Washington, DC: The National Academies Press. doi: 10.17226/27880.

Abbreviations and acronyms used without definitions in TRB publications:

A4A Airlines for America
AAAE American Association of Airport Executives
AASHO American Association of State Highway Officials
AASHTO American Association of State Highway and Transportation Officials
ACI–NA Airports Council International–North America
ACRP Airport Cooperative Research Program
ADA Americans with Disabilities Act
APTA American Public Transportation Association
ASCE American Society of Civil Engineers
ASME American Society of Mechanical Engineers
ASTM American Society for Testing and Materials
ATA American Trucking Associations
CTAA Community Transportation Association of America
CTBSSP Commercial Truck and Bus Safety Synthesis Program
DHS Department of Homeland Security
DOE Department of Energy
EPA Environmental Protection Agency
FAA Federal Aviation Administration
FAST Fixing America’s Surface Transportation Act (2015)
FHWA Federal Highway Administration
FMCSA Federal Motor Carrier Safety Administration
FRA Federal Railroad Administration
FTA Federal Transit Administration
GHSA Governors Highway Safety Association
HMCRP Hazardous Materials Cooperative Research Program
IEEE Institute of Electrical and Electronics Engineers
ISTEA Intermodal Surface Transportation Efficiency Act of 1991
ITE Institute of Transportation Engineers
MAP-21 Moving Ahead for Progress in the 21st Century Act (2012)
NASA National Aeronautics and Space Administration
NASAO National Association of State Aviation Officials
NCFRP National Cooperative Freight Research Program
NCHRP National Cooperative Highway Research Program
NHTSA National Highway Traffic Safety Administration
NTSB National Transportation Safety Board
PHMSA Pipeline and Hazardous Materials Safety Administration
RITA Research and Innovative Technology Administration
SAE Society of Automotive Engineers
SAFETEA-LU Safe, Accountable, Flexible, Efficient Transportation Equity Act: A Legacy for Users (2005)
TCRP Transit Cooperative Research Program
TEA-21 Transportation Equity Act for the 21st Century (1998)
TRB Transportation Research Board
TSA Transportation Security Administration
U.S. DOT United States Department of Transportation
Suggested Citation: "Glossary of Key Terms." National Academies of Sciences, Engineering, and Medicine. 2024. Implementing Machine Learning at State Departments of Transportation: A Guide. Washington, DC: The National Academies Press. doi: 10.17226/27880.

Suggested Citation: "Glossary of Key Terms." National Academies of Sciences, Engineering, and Medicine. 2024. Implementing Machine Learning at State Departments of Transportation: A Guide. Washington, DC: The National Academies Press. doi: 10.17226/27880.
Page 76
Suggested Citation: "Glossary of Key Terms." National Academies of Sciences, Engineering, and Medicine. 2024. Implementing Machine Learning at State Departments of Transportation: A Guide. Washington, DC: The National Academies Press. doi: 10.17226/27880.
Page 77
Suggested Citation: "Glossary of Key Terms." National Academies of Sciences, Engineering, and Medicine. 2024. Implementing Machine Learning at State Departments of Transportation: A Guide. Washington, DC: The National Academies Press. doi: 10.17226/27880.
Page 78
Suggested Citation: "Glossary of Key Terms." National Academies of Sciences, Engineering, and Medicine. 2024. Implementing Machine Learning at State Departments of Transportation: A Guide. Washington, DC: The National Academies Press. doi: 10.17226/27880.
Page 79
Suggested Citation: "Glossary of Key Terms." National Academies of Sciences, Engineering, and Medicine. 2024. Implementing Machine Learning at State Departments of Transportation: A Guide. Washington, DC: The National Academies Press. doi: 10.17226/27880.
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