Travel Time Information on Signalized Arterials

TL;DR

This paper introduces new algorithms to improve travel time data accuracy on signalized roads in Korea, reducing errors and saving costs.

Contribution

The study proposes a median-based outlier filter and an LSTM-CNN model for travel time prediction on signalized arterials.

Findings

The median-based confidence interval algorithm improves outlier filtering on suburban arterials.

The LSTM-CNN model captures both long-term and local travel time patterns effectively.

The new methods reduced error rates by 2.2% and could save USD 135,200 annually at a 4 km site.

Abstract

Travel time information has become an essential component of everyday commuting. Without such information, schedule delays would increase, leading to inevitable losses in traveler utility. In Korea, dedicated short-range communication transponders that identify vehicles have been installed along signalized arterials to collect travel time data. By matching vehicle identifications at consecutive points, travel times can be measured. However, for travel time information to be effective, two types of data processing techniques are required: outlier filtering and travel time prediction. This study proposes algorithms to address both challenges. An outlier filtering algorithm based on the median-based confidence interval was developed, taking into account the travel time characteristics on suburban arterials with frequent entry and exit points. Additionally, a travel time prediction algorithm that integrates Long Short-Term Memory (LSTM) and Convolutional Neural Networks (CNNs), referred to as LSTM-CNN, was developed to capture both long-term trends and local patterns in travel time data. The implementation of these algorithms resulted in a 2.2% reduction in error rates under congested conditions compared to current practices. At the 4 km study site, the annual benefits from this error reduction could amount to USD 135,200.

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