lean six sigma reducing pothole response time bob kennedy, street department

Lean Six Sigma

Reducing Pothole Response TimeBob Kennedy, Street Department

Pothole Formation Pothole Formation Pothole Formation

Problem Statement:

Objective:

It takes too long to respond to pothole complaints

50% Improvement in % of Potholes repaired in 24 hours

Repair 97% of potholes in 24 hours

Project Description

Team MembersTeam Members

Black Belt: Bob Kennedy

Champion: Ted Rhinehart

Brad Baumgartner - Street Department

Jill Morgan, Kim Jones - Data Input

Brooks Beatty - Street Department

Team Members

The Defects

Or The Y’s

% Potholes repaired within 24 hrs

)x,...,x,x,f(x=Y k321

DefineDefine

Definition of The YDefinition of The YDefinition of the Y

Reduced Claims Filed Against the City

Overtime Reduction for Pothole Repairs

More Positive Public Image

Rapid Citywide Pothole Repairs

Benefits

Internal Benefits

External BenefitsSafer City Initiative

Improved Customer Service

Improved Relations with Neighborhood Associations

Safer City Initiative

Improved Customer Service

Improved Relations with Neighborhood Associations

Business Case

External Benefits

23%

77%

REPAIRS COMPLETED IN 24 HOURS

Original Capability

April -September 2001

0 10 20 30 40 50 60 70 80 90

HOURS

Dot Plot for Cycle Time

April -September 2001

9080706050403020100

HOURS

Dotplot for HOURS

500400300200100Subgroup 0

100

50

0Indiv

idual V

alu

e

1

1

1

111

1

1

11

Mean=21.15

UCL=49.27

LCL=-6.962

9080706050403020100M

ovi

ng R

ange

11111 1

111

11111

11

1

1

11

R=10.57

UCL=34.54

LCL=0

I - MR Chart for HOURS

I-MR Chart

April -September 2001

120100806040200

USLLSL

Process Capability Analysis for HOURS

PPM Total

PPM > USL

PPM < LSL

PPM Total

PPM > USL

PPM < LSL

Ppk

PPL

PPU

Pp

Scale

Shape

Sample N

Mean

LSL

Target

USL

358802.50

358802.50

0.00

230088.50

230088.50

0.00

0.12

2.40

0.12

0.37

23.6829

1.8555

452

21.0330

0.0000

*

24.0000

Expected LT Performance

Observed LT Performance

Overall (LT) Capability

Process Data

Initial Capability

April -September 2001

NW 19%

SW 20%SE 27%

NE 35%

Complaints Per Quadrant

Main Effects PlotMain Effects Plot

NW NE SE SW

19.5

20.5

21.5

Quadrant

HO

UR

SMain Effects Plot - Data Means for HOURS

Main Effects Plot

One person is in charge of assigning all pothole complaints and checking for completion of work for all Quadrants.

The same person is also responsible for checking the completion of work orders on a daily basis instead of weekly.

A back-up person has also been appointed these duties in case of vacation or time off of work.

Third shift’s first priority is to check the Dispatch Office for complaints called in between 3:00pm & 11:00pm, and repair the potholes. Special lighting was added to the trucks so repairs could be made at night.

Changes Implemented

Phoned in complaints are picked up from the Dispatch Office at the beginning of each shift.

Dispatcher radios patch trucks as complaints are received. When the repair is complete the patch truck radios the dispatcher a completion time for the work order.

Dispatchers and troubleshooters are responsible for repairing potholes on week-ends and holidays when our regular crews are not in.

n

nn

Continued…

2% (5)

98% (237)

REPAIRS COMPLETED IN 24 HOURS

Improved Capability

October-December 2001

0 10 20 30

HOURS

Dotplot for Cycle Time

Dot Plot for Cycle Time

October-December 2001

25020015010050Subgroup 0

30

20

10

0

-10

Indiv

idual Valu

e 1 1

Mean=10.50

UCL=28.15

LCL=-7.150

30

20

10

0

Movi

ng R

ange

11 1

1

11 1

11

1

R=6.637

UCL=21.68

LCL=0

I - MR Chart for Cycle Time

I-MR Chart Improved Capability

October-December 2001

403020100-10

USLLSL

Process Capability Analysis

PPM Total

PPM > USL

PPM < LSL

PPM Total

PPM > USL

PPM < LSL

PPM Total

PPM > USL

PPM < LSL

Ppk

PPL

PPU

Pp

Cpm

Cpk

CPL

CPU

Cp

StDev (Overall)

StDev (Within)

Sample N

Mean

LSL

Target

USL

143831.37

52158.64

91672.73

32072.31

7948.73

24123.58

21621.62

21621.62

0.00

0.44

0.44

0.54

0.49

*

0.66

0.66

0.80

0.73

8.12238

5.47140

185

10.8070

0.0000

*

24.0000

Exp. "Overall" PerformanceExp. "Within" PerformanceObserved PerformanceOverall Capability

Potential (Within) Capability

Process Data

Within

Overall

Process Capability

October-December 2001

0.6% (3)

99.4% (463)

REPAIRS COMPLETED IN 24 HOURS

Improved Capability

2002

3020100

HOURS

Dotplot for Cycle Time

Improved Dot Plot for Cycle Time

2002

0Subgroup 100 200 300 400 500-10

0

10

20

30

40

Indiv

idual V

alu

e

11

1111

1

1

11 1

11 1

1 11 11

Mean=5.990

UCL=18.23

LCL=-6.250

0

10

20

30

40

Movi

ng R

ange

1

1

1 1

1

11

11 11

11111

R=4.602

UCL=15.04

LCL=0

I and MR Chart for Cycle Time

Improved I-MR Chart

2002

403020100

USLLSL

Process Capability Analysis for Cycle Time

PPM Total

PPM > USL

PPM < LSL

PPM Total

PPM > USL

PPM < LSL

PPM Total

PPM > USL

PPM < LSL

Ppk

PPL

PPU

Pp

Cpm

Cpk

CPL

CPU

Cp

StDev (Overall)

StDev (Within)

Sample N

Mean

LSL

Target

USL

141880.50

616.66

141263.83

71030.38

5.07

71025.31

6437.77

6437.77

0.00

0.72

0.72

2.15

1.44

*

0.98

0.98

2.94

1.96

5.57398

4.07992

466

5.9901

0.0000

*

24.0000

Exp. "Overall" PerformanceExp. "Within" PerformanceObserved PerformanceOverall Capability

Potential (Within) Capability

Process Data

Within

Overall

Improved Process Capability

2002

January-March 2003

0.4% (2)

99.6% (498)

REPAIRS COMPLETED IN 24 HOURS

Improved Process Capability

January-March 2003

20100

HOURS

Each dot represents up to 2 observations.

Dotplot for Cycle Time

Improved Dot Plot for Cycle Time

2003

500400300200100Subgroup 0

30

20

10

0Indiv

idual V

alu

e

1

11 1 1

111

11 1

1111 1

1

1

111 1

1

111

Mean=2.889

UCL=8.889

LCL=-3.111

30

20

10

0

Movi

ng R

ange

11

1111 1

11 1 111

11111111 1 111

11

1111

11 11 111

11

11

1 11

11

1

R=2.256

UCL=7.371

LCL=0

I - MR Chart for Cycle Time

Improved I-MR Chart

January-March 2003

3020100-10

USLLSL

Process Capability Analy sis f or Cy cle Time

PPM Total

PPM > USL

PPM < LSL

PPM Total

PPM > USL

PPM < LSL

PPM Total

PPM > USL

PPM < LSL

Ppk

PPL

PPU

Pp

Cpm

Cpk

CPL

CPU

Cp

StDev (Overall)

StDev (Within)

Sample N

Mean

LSL

Target

USL

185182.68

0.00

185182.68

101769.17

0.00

101769.17

4000.00

4000.00

0.00

0.30

0.30

2.18

1.24

*

0.42

0.42

3.10

1.76

3.22464

2.27174

500 2.8886

0.0000

*24.0000

Exp. "Overall" PerformanceExp. "Within" PerformanceObserved PerformanceOverall Capability

Potential (Within) Capability

Process Data

Within

Overall

Improved Process Capability

Four Quarter Moving Average

-

500.00

1,000.00

1,500.00

2,000.00

2,500.00

3,000.00

3,500.00

4,000.00

4,500.00

5,000.00

Q3'97

Q4'97

Q1'98

Q2'98

Q3'98

Q4'98

Q1'99

Q2'99

Q3'99

Q4'99

Q1'00

Q2'00

Q3'00

Q4'00

Q1'01

Q2'01

Q3'01

Q4'01

Q1'02

Q2'02

Q3'02

Q4'02

Quarter

Am

ount

of C

laim

s ($

)

Claims Against City as a Result of Pothole DamageAverage Pothole Response Time

by Quarter

3

4.8

9

5

7.7

10.5

2122.1

0

5

10

15

20

25

Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1*

2001 2002 2003

Hou

rs

* thru Feb. 28, 2003

Damage Claims Filed

Project Comparison

Repair Time

Six Sigma ProjectPothole Repair Cycle Time

36

48

19

5.6 3.4 2.5 3.5

0

10

20

30

40

50

60

1999 2000 2001 2002 2003 2004 2005

Process map revealed missing steps

Cause & effect matrix identified solutions

Average repair time down from 36 hours to 3.5 hours

Pothole Repair Cycle Time

48

15.5

5.63.4 2.5 3.5 2.9

36

0

10

20

30

40

50

60

1999 2000 2001 2002 2003 2004 2005 2006

Hou

rsYearly Pothole Cycle Time

0

10

20

30

40

50

1999 2000 2001 2002 2003 2004 2005 2006

YEARLY POTHOLE CYCLE TIMEYEARLY POTHOLE CYCLE TIME

HO

UR

SYearly Pothole Cycle Time

Hourly Process Capability

January-November 2006

24201612840-4

LSL USLProcess Data

Sample N 671StDev(Within) 2.63788StDev(Overall) 2.92226

LSL 0.00000Target *USL 4.00000Sample Mean 2.85156

Potential (Within) Capability

CCpk 0.25

Overall Capability

Pp 0.23PPL 0.33PPU 0.13Ppk

Cp

0.13Cpm *

0.25CPL 0.36CPU 0.15Cpk 0.15

Observed PerformancePPM < LSL 0.00PPM > USL 223546.94PPM Total 223546.94

Exp. Within PerformancePPM < LSL 139847.20PPM > USL 331649.53PPM Total 471496.73

Exp. Overall PerformancePPM < LSL 164579.58PPM > USL 347161.25PPM Total 511740.83

WithinOverall

Process Capability of hours

Improved Capability

January-November 2006Capability of Improved Process Jan-Nov 2006

99.85 % (670)

.15 % (1)

Repairs Completed Within 24 Hours

Dot Plot for Cycle Time

January-November 2006

hours24.521.017.514.010.57.03.50.0

Each symbol represents up to 3 observations.

Dotplot for Cycle Time Jan-Nov 2006