University of Minnesota researches effect of roundabouts on urban arterial networks


The majority of traffic management research has been largely directed toward improving traffic ?ows on congested freeways and highways, so a team from the University of Minnesota has started a project that aims to create a framework for testing and evaluating new urban traffic sensing and control strategies for arterial networks.

The University of Minnesota team’s goal is to balance safety and efficiency for all road users, especially in places where new types of urban transportation facilities are planned in the next few years, with a particular focus on the introduction of roundabouts (traffic circles) to arterial networks. The team is using the 66th Street corridor in Richfield as a test bed for its research, as the city, along with Hennepin County, is in the process of converting a series of signalized intersections along the route to roundabouts over the next few years. The roundabout designs also incorporate new facilities for pedestrians, bikes, and bus transit, as part of a multimodal approach.

Initially, the researchers sought to create a larger network of interconnected sensors and a live test bed, but funding limitations kept the project area to approximately 10 miles (16km) of arterial roads, a portion of which will be supported by a network of interconnected traffic sensors. The research team is instrumenting major intersections along 66th Street with a reliable, low-cost, high-resolution camera mounted on a center pole as the intersections are being reconstructed. The use of roundabouts has grown in the region because: they cost less to build and maintain than signalized intersections; they meet the latest design standards; and they improve safety by reducing traffic conflicts. However, predicting the capacity of roundabouts can be especially challenging when factoring in pedestrian traffic, uneven traffic origin-destination flow, heavy vehicle volumes, and approach vehicle gap-selection timing.

In addition to creating a sensor network to obtain real-time vehicle and pedestrian data to help control traffic and keep it flowing smoothly, the researchers also are developing a traffic simulation model that includes almost all of Richfield. A team from the Minnesota Traffic Observatory (MTO), led by director John Hourdos, is creating the simulation model, which covers more than 140 signalized intersections over 21 square miles (54sq km), including the arterials, that will be used to develop and test traffic control strategies under different scenarios. The research and the field deployment system are funded through a collaborative grant from the National Science Foundation Cyber Physical Systems program, with SRF Consulting acting as the industrial partner to help design the sensor network and evaluate the system.

“There’s been a lot of research focused on controlling congestion on major highways and freeways, but there’s relatively less when it comes to looking at controlling traffic on urban arterials,” said Ted Morris, a research engineer with the U of M’s Department of Computer Science. “It’s a very different picture when you get into urban arterials and the traffic behaviors going on there, because of the dynamics of route choice, pedestrian interactions, and other factors.”

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Tom has edited Traffic Technology International (TTi) magazine and its Traffic Technology Today website since May 2014. During his time at the title, he has interviewed some of the top transportation chiefs at public agencies around the world as well as CEOs of leading multinationals and ground-breaking start-ups. Tom's earlier career saw him working on some the UK's leading consumer magazine titles. He has a law degree from the London School of Economics (LSE).