Modeling Traffic Jams in Houston

Date: Apr. 30, 2019

Congestion heatmap of the Houston highway system.

Traffic congestion, a major concern of present societies, has plagued cities around the world for millennia. Historical literary and archaeological sources mention cases of traffic congestion within cities and harbor gates in ancient cities like Rome, Pompeii and Xanten (Tilburg, 2007). Today, despite the advancements in infrastructure and technology, congestion remains one of the leading concerns of urban societies (Miovision, 2012). In the United States alone, congestion results in an annual economic loss of 305 billion (Pyzk, 2018) with 17 cities, such as New York, Austin and Houston, having over 90 hours lost annually in congestion on average per capita (INRIX, 2018).

The aim of this study is to assess the vehicular network in Houston, Texas, using data provided by Française des Jeux Mathématiques and Société de Calcul Mathématique SA. At the highest level of road hierarchy, Houston’s road network consists of multiple Interstate freeways, ring roads and state highways, with varying levels of traffic activity. The extent of activity dictates the nature of traffic flow throughout different segments of the road, from uncongested free-flow scenarios with barely any vehicles on the highway to breakdown conditions where the highway operates at very low speeds and in a stop-and-go fashion.

To assess traffic conditions and investigate possible improvements, however, a model that describes the system and can predict appearances of traffic jams is needed. The literature is rich with are a multitude of microscopic and macroscopic approaches to modeling traffic flow, with some of the most prominent, such as Greenshields and Lighthill-Whitham-Richards presented here. Using these models, the traffic flow, density and speed at different segments of the highway system are estimated. These values allow to assess the congestion level at these segments along with the remedies and modifications required to improve the traffic situation.

Modification can have a large range, from geometric modification, such as adding or widening lanes, to more implicit methods, such as demand management through incentives to change trip times or use transit instead. These approaches to improving traffic conditions on the highway system are explored

In this project ,we present an overview of the traffic data and the preliminary data processing and implementations of the Greenshields and Lighthill-Whitham-Richards (LWR) traffic models. In addition, we discuss the operational aspects of traffic congestions using the Highway Capacity Manual to assess road congestion and operations, present the potential strategies and simulate three of such strategies as potential interventions for Houston’s highway system.

 

Speed simulation as a function of transit fraction and induced demand (Greenshields model).

Full report: https://sites.northwestern.edu/aprilzhizhou/files/2023/04/Submission_MaherSaid_EmmaZajdela_ZhiZhou.pdf