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