I-55 Stevenson Expressway (Lakeshore Drive to I-294)

I-55 Stevenson Expressway (Lakeshore Drive to I-294)

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, congested hours, and crash scans.

Highway Congestion Scans TEST

Congestion Scans

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.

2011

I-55, Stevenson Expressway from US 41/Lake Shore Drive to I-294 Congestion Scan - 2011, showing average speed by milepost by time of day.

I-55, Stevenson Expressway from US 41/Lake Shore Drive to I-294 Congestion Scan - 2011 (PDF version)

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2009

I-55, Stevenson Expressway from US 41/Lake Shore Drive to I-294 Congestion Scan - 2009, showing average speed by milepost by time of day. Click on graphic to open congestion scan; click again to improve graphic resolution.

I-55, Stevenson Expressway from US 41/Lake Shore Drive to I-294 Congestion Scan - 2009 (PDF)

2007

I-55, Stevenson Expressway from US 41/Lake Shore Drive to I-294 Congestion Scan - 2007, showing average speed by milepost by time of day. Click on graphic to open congestion scan; click again to improve graphic resolution.

I-55, Stevenson Expressway from US 41/Lake Shore Drive to I-294 Congestion Scan - 2007 (PDF version)

Definitions

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.

Crash Scans Test

Crash Scans

Crash scans show the rate of total highway crashes per 100 million vehicle-miles traveled (VMT) for 1/10 mile segments. The purpose of these crash scans is to show highway planners and system managers how crashes are related to congestion. Understanding where crashes are concentrated can help planners and engineers focus on improving those locations with the worst performance.

I-55, US 41 to I-90/94 Crash Scan, 2008-2012

I-55, US 41 to I-90/94 Crash Scan 2008-2012 (click for pdf version)

 

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I-55, I-90/94 to I-294 Crash Scan 2008-2012

I-55, I-90/94 to I-294 Crash Scan 2008-2012 (click for pdf version)

 

TEST Performance Data

Performance Data

Non-holiday Tuesdays, Wednesdays, and Thursdays

East-bound Elgin-O'Hare Expressway

Measure 2007 2008 2009 2010 2011
Free-Flow Travel Time
(Minutes)
5.64 5.66 5.64 5..62 5.60
Average AM Peak-Period
Travel Time (Minutes)
9.27 9.35 8.44 8.20 8.20
AM Travel Time Index 1.64 1.65 1.50 1.46 1.46
Average PM Peak-Period
Travel Time (Minutes)
6.17 6.48 6.15 6.00 6.08
PM Travel Time Index

1.09

1.14

1.09

1.07 1.08
AM Peak-Period
95th Percentile Travel Time
(Minutes)

14.58

15.11

14.40

11.99 12.21

AM Peak-Period
Planning Time Index

2.59

2.67

2.55

2.13 2.17
PM Peak-Period
95th Percentile Travel Time
(Minutes)

6.72

7.34

6.86

6.39 6.54
PM Peak-Period
Planning Time Index

1.19

1.30

1.22

1.14 1.16
Congested Hours

4.10

3.76

3.00

2.48 2.63
 

 

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West-bound Elgin-O'Hare Expressway

Measure

2007

2008

2009

2010 2011
Free-Flow Travel Time
(Minutes)

5.53

5.65

5.52

5.60 5.59
Average AM Peak-Period
Travel Time (Minutes)

6.36

6.34

6.27

6.34 6.32
AM Travel Time Index

1.15

1.14

1.14

1.13 1.13
Average PM Peak-Period
Travel Time (Minutes)

8.49

8.64

7.42

7.69 7.78
PM Travel Time Index

1.53

1.55

1.34

1.37 1.39
AM Peak-Period
95th Percentile Travel Time
(Minutes)

6.99

6.98

6.91

6.90 6.88

AM Peak-Period
Planning Time Index

1.26

1.26

1.25

1.23 1.23
PM Peak-Period
95th Percentile Travel Time
(Minutes)

12.66

13.95

10.92

11.41 11.56
PM Peak-Period
Planning Time Index

2.29

2.51

1.98

2.04 2.07
Congested Hours

3.94

3.45

2.21

2.56 2.71

 

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