What is the Maricopa County DOT
The Maricopa County Department of Transportation (MCDOT) plans, designs, constructs, and maintains roadways within the county’s unincorporated areas.
To provide transportation infrastructure and related services to the people within Maricopa County so they can live, conduct business and travel in a safe and clean environment.
MCDOT performs in a collaborative, innovative, efficient and effective manner to deliver safe, cost-effective infrastructure that is responsive to our customers.
Maricopa County has a population of approximately four million, and is the fourth most populous county in the US. With more than nine-thousand square miles it is larger than seven different states. The County is administered by a County Manager who reports to the five member Board of Supervisors elected by the public.
View the Department's Organizational Chart
Meet the MCDOT Management Team
The Maricopa County Department of Transportation (MCDOT) plans, designs, constructs, operates and maintains roadways within the County’s unincorporated areas. MCDOT is responsible for the operation and maintenance of approximately 2,500 miles of roadway, more than 80 bridges (16 of them greater than 400 feet long) and more than 325 culvert crossings, more than 160 signalized intersections and nearly 35,000 traffic signs. MCDOT’s funding is primarily derived from Highway User Revenue Funds, and other federal and state sources. Maricopa County has a population of approximately four million, and is the fourth most populous county in the United States. With more than nine-thousand square miles it is larger than Connecticut, Delaware and Rhode Island combined.
MCDOT’s funding is primarily derived from Highway User Revenue Funds, and other federal and state sources.
Jennifer Toth, P.E.
Jennifer Toth brings more than 16 years of experience in transportation engineering to her role as MCDOT Director and County Engineer, one of the largest counties in the United States. Before joining MCDOT in 2014, Jennifer served as State Engineer and Deputy Director of the Arizona Department of Transportation with responsibility for planning, designing, constructing, maintaining and operating more than 6,000 miles of interstate and state highways in Arizona. She has also worked in the private sector as a transportation consultant.
Jennifer serves on a planning committee for the National Research Council’s Transportation Research Board and holds a Bachelor of Science degree in Civil Engineering from the University of Houston and a Master of Science degree in Civil Engineering from the University of New Mexico. She brings to MCDOT a passion for public service and meeting the transportation needs of the residents of Maricopa County.
Teresa Welborn brings more than 25 years of experience in the government and non-profit sectors to her position as Administrator for the Maricopa County Department of Transportation. She oversees the divisions of Financial Services and Information Technology, and Communications. Teresa provides experience in program, contract and budget management, strategic planning, process improvement, communications, media relations and community outreach. Previously, Teresa was with the Arizona Department of Transportation where she served as Partnering Administrator and Assistant Communications Director. Teresa holds a Bachelor of Science Degree in Finance from the University of Arizona and a Masters of Education degree in Educational Leadership from Northern Arizona University. Teresa is a member of the WTS Phoenix Metropolitan Chapter and serves on the WTS International Foundation Board.
Ed Williams has over 19 years of civil engineering experience. Before joining MCDOT as the Engineering Division Manager in 2012, he worked as a design engineer and project manager on commercial developments and tribal projects for J&K Engineering in Prescott, Arizona. He has also worked at Parsons Transportation Group in Denver, Colorado as well as a number of small local firms in Boulder, Colorado and Prescott, Arizona. Ed earned a Bachelor of Science in Civil Engineering from the Georgia Institute of Technology. He is a member of the American Society of Civil Engineers, Engineers without Borders and the American Public Works Association.
Nicolaas Swart has been the Traffic Management Division Manager since 2006. He oversees all aspects of Traffic Engineering and Intelligent Transportation Systems (ITS). He comes to MCDOT with a strong international engineering background. Before joining MCDOT he worked for Associated Engineering (B.C.) Ltd. in Canada and Ninham Shand, Inc. in South Africa. Nicolaas earned his Bachelor of Science in Civil Engineering and his post-graduate degree in Transportation Engineering from the University of Pretoria in South Africa. He is a member of the State Board of Technical Registration of Arizona, the Association of Professional Engineers and Geoscientists of British Columbia, the Intelligent Transportation Society of Arizona and the Institute of Transportation Engineers. He also serves as the Program Manager for AZTech, a partnership of local agencies integrating transportation systems across jurisdictional boundaries through traffic management and ITS solutions.
Mark Modin has worked with MCDOT since 1982. As Financial Services Division Manager, he oversees all departmental budgets, Facilities, Article 3 and 5 Procurement, Customer Service and Custodian of Records. Before joining MCDOT, he worked in auditing for the State of Wisconsin Department of Health Services as well as in Financial Services for the Maricopa County Schools Department. Mark earned his Bachelor of Arts in Business Administration with a major in Accounting from Washington State University. He is a member of the Association of Governmental Accountants and holds an Arizona Certified Public Accountant license.
Mike Wilson SR/WA
Real Estate Division Manager
Mike Wilson joined MCDOT in 1997 as the Real Estate Division’s Property Management Supervisor and became the Division Manager in 2002. As Division Manager, he is on both MCDOT and the Maricopa County Flood Control District’s management teams. Prior to joining MCDOT, he worked for the Arizona State Land Department, holding several supervisory positions in the Range, Environment, Trespass Mitigation and Right of Way sections. He has also worked in farming, ranching and commercial cattle feeding management throughout Iowa and Nebraska. Mike earned his Bachelor of Science in Business Administration (Agri-business) from Iowa State University. He holds an Arizona Real Estate License and a Senior Right of Way Associate Designation from the International Right of Way Association.
Roseann Osborn-Perez has worked with the County since 1982. She started her career as a Management Information Systems (MIS) Specialist, working her way up to become the Information Technology (IT) Division Manager. Positions she has held include MIS Supervisor, an Assistant Project Manager and Application/Program Manager with the Maricopa County Health Services Department. As IT Division Manager, she is responsible for evaluating and bringing technology to MCDOT business processes to help departments be more efficient. Roseann earned her Bachelor of Science in Business Administration specializing in Management Information Systems with a minor in Computer Science from Glassboro State College in New Jersey.
Kevin Kottmer has over 30 years of professional government service, beginning his career at MCDOT as a Summer Aide Intern. Kevin advanced through several MCDOT positions and Divisions including Operations, Procurement, Engineering, Traffic Management, Project Management & Construction and Real Estate. Kevin also gained valuable experience working at the Arizona Department of Emergency Management and Military Affairs. Kevin is an active member of the Local Arizona Chapter of the American Traffic Safety Service Association (ATSSA). Kevin holds certifications including ATSSA Certified Traffic Control Supervisor and ATSSA Certified Flagger Instructor. Kevin is responsible for Roadway Maintenance, Traffic Maintenance, Maintenance Support and Fleet Maintenance. He finds great satisfaction in assisting the residents of Maricopa County.
You can contact MCDOT by either calling the customer service number at the information below or or online
2901 W. Durango
Phoenix, Arizona 85009
(Southwest corner of 29th Ave & Durango)
Phone: (602) 506-8600
Fax: (602) 506-4750