This first feature in a series on Milwaukee, WI, USA-site of the ITE 2006 Annual Meeting and Exhibit-focuses on how the Wisconsin Department of Transportation is managing community needs and traffic impacts during the reconstruction of the Marquette Interchange.

INTRODUCTION

In the heart of downtown Milwaukee, WI, USA, host of the ITE 2006 Annual Meeting and Exhibit, the busy thoroughfares of Interstates 43, 94 and 794 inter sect to form the Marquette Interchange. Built between 1964 and 1968, the fivelevel interchange is undergoing a complete reconstruction. A significant makeover was needed because the interchange structures were at the end of their useful lives; crash rates were high and traffic volumes were double the number the interchange was intended to handle when it opened.

Before the $810-million, 5.5-mile reconstruction could be launched, however, the Wisconsin Department of Transportation (WisDOT) needed to address and manage community needs in downtown Milwaukee.

The Marquette Interchange serves as the gateway to Milwaukee for residents, business and tourism. It links Milwaukee's economy to the rest of the state. A total of 66,000 people live in downtown Milwaukee, and 121,000 workers are employed at 4,300 businesses. More than 7 million tourists per year visit cultural attractions and festivals.

To manage the community's needs, the Marquette Interchange needed to be built in a way that kept downtown open for business and minimized the impact of construction on tourism. In 2002, three years before major construction would start, WisDOT gathered leaders from the community to develop ideas that would mitigate traffic impacts during the mega-reconstruction project.

NEED FOR A NEW INTERCHANGE

The main system interchange (1-43/ 94/794) originally was built with a combination of left-hand and right-hand ramps that were closely spaced to service entrance and exit ramps. This caused severe weaving movements that contributed to traffic congestion and crashes.

When the interchange was opened to traffic in 1968, drivers used studded tires during winters for better traction. However, the studded tires combined with salting operations caused the structures to deteriorate rapidly. The structures continued to deteriorate as time passed, and the interchange required complete reconstruction to avoid weight-limitation postings for trucks. Trucking restrictions would have been an obvious detriment to the state's economy.

The design of the reconstructed interchange eliminates the weaving sections by shifting all system and service ramps to the right-hand side; increases the design speeds of the system ramps to reduce the speed differential between the ramp and mainline movements; expands some system ramps to two lanes to provide additional throughput capacity; and lengthens the merging distances from ramps to mainline.

The future interchange will be built on the existing interchange's tight urban footprint, with only a small change in the total right of way required for the new interchange. The new interchange design is shown in Figure 1.

ANTICIPATED IMPACTS

Construction of the interchange is now in its second of four years of freeway impact. Preparatory work off the freeway began in 2004. The scheduled completion date for the entire project is December 2008, with the northern section of the project set for an interim completion date of October 2006.

To meet the needs of the community, the project team had to carefully balance keeping freeway lanes and ramps open while limiting the total time that the downtown interchange would be under construction. To facilitate construction, the east-west and north-south sections of the project are being built in halves. In 2005, the southbound direction of 1-43 was rebuilt while both directions of traffic used the northbound side, as shown in Figure 2.

To accommodate both directions of traffic on one side of the freeway, the sixlane section with full shoulders was reduced to a four-lane section with limited shoulders and lane widths. Almost 300,000 vehicles use the interchange on a daily basis; peak-hour capacity was expected to be reduced by 40 percent.

Temporary bridges and roadways were constructed to ensure that two lanes of traffic are open to through-traffic movements during peak hours during the life of the project. Temporary system ramps also were constructed to accommodate the largest turning movements in the interchange. Although the temporary construction helped facilitate keeping some traffic from diverting, other lesser-used system ramps will be closed for as many as three years.

To fully understand the anticipated traffic diversions that would result from the reconstruction, WisDOT worked closely with the Southeast Wisconsin Regional Planning Commission (SEWRPC), which integrated the anticipated lane and ramp closures into its travel-demand model. During the construction staging engineering process, SEWRPC examined a number of construction staging alternatives to help the project team identify the staging sequence that minimized the impact to the local street system and the community as a whole.