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2.1 SEMCOG Responsibilities

SEMCOG, the Southeast Michigan Council of Governments, is the metropolitan planning organization (MPO) for the seven-county southeast Michigan region of Livingston, Macomb, Monroe, Oakland, St. Clair, Washtenaw, and Wayne Counties, and which includes the City of Detroit and the surrounding metropolitan area. SEMCOG was established in 1968 as a regional planning partnership in southeast Michigan. The agency is responsible for developing the federally-mandated Regional Transportation Plan (RTP) and the Transportation Improvement Program (TIP). SEMCOG is also responsible for calculating and documenting on-road mobile source emissions for both the State Implementation Plan (SIP) and the regional air quality/conformity analysis. The TDFM and its underlying theory are key support tools for this core work.

2.2 Regional Characteristics

In its application for the TMIP peer review, SEMCOG outlined some of the characteristics and trends in the southeast Michigan region that offer unique challenges to their travel demand modeling efforts. These include decline in population, significant changes in land use and the structure of the workforce, the decline of certain economic sectors and opportunities for the growth of others. The region is tightly knit from a supply chain standpoint with Ontario, Canada, with a substantial amount of the automotive industry operating on both sides of the border. Some MPOs are grappling with these challenges, but most are not experiencing the same loss of jobs and attendant lack of economic growth that SEMCOG is facing.

The population of the region increased from 4,833,368 in 2000 to a peak of 4,898,449 in 2005, before declining to 4,782,407 in 2010.[1] Wayne County was the only county that saw a decline in its population in the last decade from 2,061,162 in 2000 to 1,897, 499, but its decline in population surpasses the gains in the rest of the region's counties combined. The population decline has been driven by out-migration, with net out-migration of about 270,000 between 2000 and 2010.

The depressed economy and weak housing market during the second half of the last decade have resulted in very little homebuilding activity in the region. In 2009, 1,590 new home permits were issued in the region, which was only seven percent of the annual average number of permits issued during the first half of the decade. Population losses, coupled with the housing crash, have resulted in nearly 236,000 vacant housing units in the region. Between 2000 and 2010, vacant housing units in the region increased by more than 120 percent.

The employment market in the region contained a total of 1,874,815 jobs [2] at the end of the first quarter of 2009. The size of the job market declined by 8.3% between the first quarters of 2008 and 2009, which followed annual declines in total jobs in every year since 2001.

The falling population and weak economy have contributed to a decline in traffic in the region. Between 2004 and 2009, weekday traffic decreased each year from 142.7 million vehicle miles traveled in 2003 to 123.7 million vehicle miles traveled in 2009, a decline of more than 13 percent. Weekend travel was also down by nearly 10 percent over the same time period.[3]

2.3 SEMCOG Goals for Peer Review

SEMCOG applied for this peer review as they were coming close to completing over a decade of model and data improvements that have resulted in what the agency describes as a "best practice trip-based travel modeling system", which has included interaction with an UrbanSim land use model for the past several years. The recent development path of the model is based in part on an earlier TMIP peer review panel that met in December 2004. At the time of this peer review in December 2011, most of the major recommendations of the 2004 peer review panel have been completed or are close to implementation.

SEMCOG expects to gradually transition from a trip-based model to an advanced model, as both the 2004 peer review panel and consultants working for SEMCOG have recommended the consideration of advanced models in the longer term. SEMCOG engaged the consultant Parsons Brinckerhoff in 2011 to independently assess the agency's modeling program and plans for future improvements. Part of their role was to recommend a future for travel modeling at SEMCOG.

While SEMCOG expressed keen interest in the panel's recommendations about all aspects of their modeling program, their specific goal for the peer review was to discuss three subjects:

What the panel believe the future of travel data collection looks like, and the steps that SEMCOG should take to capitalize upon new methods for collecting travel data.

[1] Population and Households in Southeast Michigan, 2000-2010, available at

[2] Jobs and Earnings in Southeast Michigan, First Quarter 2008 and 2009, available at

[3] Traffic decline continues in Southeast Michigan, available at

Updated: 5/14/2016
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