Michigan DOT Flex Route 23 News September 2017

Flex Route 23 News

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September 2017 

Flex Route 23 will improve travel today and for decades to come 

 Flex Route 23 Lanes

Flex Route lanes under construction. Soon these lanes will be finished with new pavement markings. 

Located north of Ann Arbor between M-14 and M-36 (9 Mile Road), construction of the new Flex Route 23 is on schedule and expected to be fully operational by the end of the year. The Flex Route is designed to reduce travel time and improve safety. Motorists already are driving under the electronic signs that have been installed above the roadway – signs that soon will be advising them as to which lanes are open and closed, and posting alerts regarding any incidents that may be ahead. Within months, something else will be taking place along this route: New research project will study the wear rate of the Flex Route's pavement markings. 

"Next year, smart cars will start collecting baseline data to measure the rate at which the materials we use for pavement markings degrade over time," said Andre Clover, P.E., research program manager for the Michigan Department of Transportation (MDOT). "We will be evaluating the car’s ability to detect these road markings, which will tell us how often we need to restripe the roads to fully support connected and automated vehicles (CAVs)." 

Throughout the winter months, pavement markings in Michigan typically get distressed by snowplows and chemicals used for melting ice. This constant wear and tear, along with snow-covered roads, causes the pavement markings to become less clear, which can make it difficult for some drivers to tell if a road is straight or curved – and exactly where the center of the road is. 

The smart cars will be driven by researchers from the University of Michigan who operate Mcity, a test facility that already has become a hub for CAV mobility research in Michigan. Mcity provides a controlled environment where simulated tests enable researchers to assess CAVs and their ability to communicate with the infrastructure and road signs. This research will progress to real-world testing, once Flex Route 23 is operational. 

"We want to know at what point an autonomous vehicle’s technology is no longer able to detect the pavement markings," said James Sayer, director of theUniversity of Michigan Transportation Research Institute. "We plan to collect regularly scheduled measurements during both clear and adverse weather conditions." 

The autonomous vehicles will be equipped with a light detection and ranging (LIDAR) unit, along with a camera. LIDAR uses pulsed light to survey or sweep the road in circular and vertical motions. These sweeps then send detailed 3-D images to the smart car’s computer, capturing the vehicle’s surroundings and discerning the difference between a car and a truck, a bicycle and a motorcycle, and even an adult and a child. Because LIDAR cannot read words and it could be adversely impacted by fog and snow, it relies on a camera to detect any road signs ahead. The technologies work together to generate a reaction from the car, causing it to slow down, move over, or take some other appropriate action. Technology is key to this pavement marking research.  

The new Flex Route also will utilize Intelligent Transportation System (ITS) technology, including a lane control system consisting of overhead signs, cameras, and electronic message boards that will be constantly monitored and adjusted as needed to advise motorists and promote safety. Flex Route 23 will be equipped with the technology to improve the safety and capabilities of roadways today and for decades to come. 

As work continues in order to meet the year-end completion date, MDOT encourages motorists to slow down in work zones to promote the safety of workers and motorists alike. 

Current and upcoming construction activities(See map)


  • M-14 to North Territorial Road: Traffic has been shifted onto the flex lane and middle lane for most of this section. Concrete patching of the existing right lane continues. The median barrier wall and interchange lighting, starting at the westerly M-14/US-23 split to just south of Joy Road, is nearly complete.
  • North Territorial Road to Barker Road: Construction continues within the median nightly for the proposed Flex Route lane. Traffic has been shifted onto the Flex Route and middle lanes for most of this section. Construction continues on the existing right lane. Ramp acceleration and deceleration extensions are complete except for the 6 Mile Road southbound and northbound on ramps. 
  • Barker Road to 8 Mile Road: This section of the project is now in Stage 2, which includes full reconstruction of the northbound roadway. Four lanes of traffic are being maintained on the newly constructed southbound side of US-23. Northbound traffic is shifted to the southbound roadway using temporary crossovers placed south of Barker Road and north of 8 Mile Road. To date, the overpass for the Great Lakes Central Railroad has been removed and construction of a new bridge is in process. The Barker Road bridge deck hydro demolition and overlay is complete, the box culvert work is underway, and a considerable portion of the roadway embankment has been placed. The contractor anticipates shifting the two northbound lanes back onto northbound US-23 in mid-October.

Intelligent Transportation System (ITS):

 Overhead Gantry Testing

Testing of the overhead gantries along Flex Route 23.

  • ITS equipment, devices, and infrastructure installation is complete along the length of the project. Local device testing and system integration has begun. 


 North Territorial Road interchange

Aerial view of the Flex Route construction and the North Territorial road interchange.

  • North Territorial Road: The interchange, proposed ramps, and both roundabouts are open. 5 Mile Road is anticipated to open by the end of September.   
  • 6 Mile Road: Bridge reconstruction and asphalt approach work are complete and the roadway is open to traffic. The southbound on ramp is currently closed for reconstruction through mid-November.  
  • 8 Mile Road: Asphalt paving of the roundabout is complete. All ramps except for the northbound off ramp are open. The northbound off ramp is closed for reconstruction in conjunction with the northbound US-23 reconstruction. The ramp will remain closed through mid-November. The northbound on ramp is tentatively scheduled to close on Sept. 23. The ramp closure is needed to complete the reconstruction of the acceleration lane. Concrete surface coating of the bridge is underway. 

Warren and Joy Road Structures: 

  • Repairs on the Joy Road bridge are nearly complete except for concrete surface coating. Additional work to replace a damaged beam on this structure is scheduled to begin in mid-October. A temporary traffic signal will maintain traffic in both directions while this work is taking place. 
  • Repairs on the Warren Road Bridge are nearly complete except for concrete surface coating. A temporary traffic signal maintains traffic in both directions while this work is taking place.

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