Seifeldeen Eteifa

and 3 more

Predicting signal phase and timing (SPaT) most likely switching times and confidence level is needed to enhance green light optimal speed advisory (GLOSA) systems. This study proposes an architecture based on transformer encoders to improve prediction performance. This architecture is combined with different deep learning methods, including Multilayer perceptrons (MLP), long-short-term memory neural networks (LSTM), and Convolutional long-short term memory neural networks (CNNLSTM) to form an ensemble of predictors. The ensemble is used to make data-driven predictions of SPaT information for six different intersections along the Gallows Road corridor in Virginia. The study outlines three primary tasks. Task one is predicting whether a phase would change within 20 seconds. Task two is predicting the exact change time within 20 seconds. Task three is assigning a confidence level to that prediction. The experiments show that the proposed transformer-based architecture outperforms all the previously used deep learning methods for the first two prediction tasks. For the first task, the transformer encoder model provides an average accuracy of 96%. For task two, the transformer encoder models provided an average mean absolute error (MAE) of 1.49 seconds, compared to 1.63 seconds for other models. Consensus between models is shown to be a good leading indicator of confidence in ensemble predictions. The ensemble predictions with the highest level of consensus are within one second of the true value for 90.2% of the time as opposed to those with the lowest confidence level, which are within one second for only 68.4% of the time.

Kyoungho Ahn

and 1 more

Hydrogen fuel cell vehicles (HFCVs) are a promising technology for reducing vehicle emissions and improving energy efficiency. Due to the ongoing evolution of this technology, there is limited comprehensive research and documentation regarding the performance of HFCVs. To address this void, the paper develops a simple HFCV energy consumption model using new fuel cell efficiency estimation methods. The suggested energy efficiency model employs real-time vehicle speed, acceleration, and roadway grade as input parameters for calculating instantaneous hydrogen energy consumption rates, battery energy consumption, and total energy consumption. The results suggest that the model's forecasts align well with real-world data, demonstrating average error rates of 0.0% and -0.1% for fuel cell energy and total energy consumption across all four cycles. However, it was observed that the error rate for a particular cycle, such as the UDDS, can be as high as 13.1%. Moreover, the study confirmed the reliability of the suggested model through validation with independent data. The findings indicated that the proposed model precisely predicted energy consumption, with an error rate of 6.7% for fuel cell estimation and 0.2% for total energy estimation compared to empirical data. Additionally, instantaneous SOC predictions from the model closely match observed instantaneous SOC measurements, highlighting the model's effectiveness in estimating real-time changes in the battery SOC. The study investigated the energy impact of various intersection controls to assess the applicability of the proposed energy model. The simplicity of the proposed model enables easy estimation of energy consumption using traffic simulation models.