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Questions or comments? Contact Tom Murtha.

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Highway Congestion Scans

As part of CMAP's Congestion Management Process, select performance measures for the regional freeways have been created from five minute speed data obtained from the Illinois Department of Transportation (IDOT) and Traffic.com. These performance measures include congestion scans, travel time index, planning time index, and congested hours.

The Chicago region traffic congestion scans were created by averaging five minute speed data obtained from freeway loop detectors and mobile technology data. The traffic scans display average speed on a freeway corridor as a function of time of day (the x-axis) and location (the y-axis) along a freeway corridor.

The travel time index is a measure of average congestion and indicates the average extra travel time required during peak period congestion. Travel time index is a ratio of the average peak-period travel time compared to the free-flow travel time. For example, a value of 1.20 means that average peak travel times are 20 percent longer than free-flow travel times.

The planning time index is a measure of reliability and is defined as the ratio of the total time needed to ensure a 95 percent on-time arrival to the free-flow travel time. For example, a value of 1.4 means that, to arrive on-time 95 percent of the time, a traveler should budget an additional eight minutes for a trip that takes 20 minutes during off-peak, free-flow conditions.

Congested hours are an indication of how many hours per day a facility is congested. Technically, "congested hours" are defined as the average number of hours in which at least 20 percent of the vehicle miles traveled (VMT) on the instrumented segment is congested. For this measure, congestion is defined to occur when link speeds are less than 50 mph.

Data provided by IDOT, Illinois Tollway, and Traffic.com. CMAP's Todd Schmidt created the performance measures.

Freeway Segments

The updated scans and performance measures are expected to be available in January 2014.  To obtain this data, contact Tom Murtha.

Elgin-O'Hare Expressway (IL-53 to US 20)
I-55 Stevenson Expressway (Lakeshore Drive to I-294)
I-55 (I-294 to Veterans Parkway)
I-57 (I-94 to I-80)
I-80/94 Kingery Expressway (Indiana State Line to I-294)
I-80 (I-294 to US 45)
I-88 Reagan Memorial Tollway (I-294 to Mitchell Road)
I-88 Reagan Memorial Tollway (I-294 to I-355)
I-88 Reagan Memorial Tollway (I-355 to Mitchell Road)
I-90/94 Dan Ryan Expressway (Local Lanes I-90 Skyway to I-55)
I-90/94 Dan Ryan Expressway (Express Lanes I-90 Skyway to I-55)
I-90/94 Kennedy Expressway (Local Lanes I-290 to I-94 Edens Split)
I-90/94 Kennedy Expressway (Reversible Lanes Ogden Avenue to Montrose Avenue)
I-90 Kennedy Expressway (I-94 Edens Split to I-190)
I-90 Jane Addams Memorial Tollway (I-294 to Elgin Avenue)
I-90 Jane Addams Memorial Tollway (I-294 to I-290/IL-53)
I-90 Jane Addams Memorial Tollway (I-290/IL-53 to IL-31)
I-90 Jane Addams Memorial Tollway (IL 31 to County Line Road, McHenry County)
I-94 Bishop Ford Freeway (I-80/I-294 to I-57)
I-94 Dan Ryan Expressway (I-57 to I-90 Skyway)
I-94 Edens Expressway (I-90 to Deerfield Road)
I-94 Edens Spur (I-94/US 41 Edens Expressway to I-294)
I-94/I-294 Tri-State Tollway (I-90 to Everett Road)
I-94/I-294 Tri-State Tollway (Everett Road to Old Skokie Road)
I-190 (I-90 to Chicago O'Hare International Airport)
I-290 Eisenhower Expressway (Canal Sreet to Wolf Road)
I-290 (Wolf Road to I-90/Jane Addams Tollway)
I-290 (Wolf Road to I-355/IL-53)
I-290 (I-355/IL-53 to I-90/IL-53)
I-294 Tri-State Tollway (I-94/Bishop Ford Freeway to I-55)
I-294 Tri-State Tollway (I-55 to I-90)
I-355 Veterans Memorial Tollway (I-80 to I-55)
I-355 Veterans Memorial Tollway (I-55 to I-88)
I-355 Veterans Memorial Tollway (I-88 to IL-64/North Avenue)
IL-53 (I-290/I-90 to Lake Cook Road)
US 41 Lake Shore Drive (Hollywood Avenue to Jackson Boulevard)
US 41 Lake Shore Drive (Roosevelt Road to Marquette Drive)

 

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