Development and Evaluation of Recurrent Neural Network based Models for Hourly Traffic Volume and AADT Prediction

TL;DR

This study develops and evaluates RNN-based models, especially LSTM, for predicting hourly traffic volumes and AADT, addressing seasonal variations and missing data with imputation techniques, outperforming traditional models.

Contribution

Introduces robust RNN models with imputation methods for high-resolution traffic prediction, demonstrating superior performance over traditional approaches.

Findings

LSTM outperforms simple RNN and GRU models.

Imputation methods outperform masking for missing data.

The LSTM-Median model achieves the best accuracy with RMSE of 274 and MAPE of 18.91%.

Abstract

The prediction of high-resolution hourly traffic volumes of a given roadway is essential for transportation planning. Traditionally, Automatic Traffic Recorders (ATR) are used to collect this hourly volume data. These large datasets are time series data characterized by long-term temporal dependencies and missing values. Regarding the temporal dependencies, all roadways are characterized by seasonal variations that can be weekly, monthly or yearly, depending on the cause of the variation. Regarding the missing data in a time-series sequence, traditional time series forecasting models perform poorly under the influence of seasonal variations. To address this limitation, robust, Recurrent Neural Network (RNN) based, multi-step ahead forecasting models are developed for time-series in this study. The simple RNN, the Gated Recurrent Unit (GRU) and the Long Short-Term Memory (LSTM) units are used to develop the model and evaluate its performance. Two approaches are used to address the missing value issue: masking and imputation, in conjunction with the RNN models. Six different imputation algorithms are then used to identify the best model. The analysis indicates that the LSTM model performs better than simple RNN and GRU models, and imputation performs better than masking to predict future traffic volume. Based on analysis using 92 ATRs, the LSTM-Median model is deemed the best model in all scenarios for hourly traffic volume and AADT prediction, with an average RMSE of 274 and MAPE of 18.91% for hourly traffic volume prediction and average RMSE of 824 and MAPE of 2.10% for AADT prediction.