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POTHOLES IN EDMONTON Updated: April 4, 2013

Mack Male http://www.mastermaq.ca

Abstract Every year the City of Edmonton spends a few million dollars to fill a few hundred thousand

potholes. Are potholes just a fact of life, or can we do something about them? It’s time for a more sophisticated and creative discussion about potholes in Edmonton.

1

POTHOLES IN EDMONTON

Table of Contents Pothole Primer .............................................................................................................................................. 2

How do potholes form? ............................................................................................................................ 2

How many potholes are there in Edmonton? ............................................................................................... 3

How much does Edmonton spend fixing potholes? ..................................................................................... 4

How does Edmonton compare to other Canadian cities? ............................................................................ 6

How many kilometers of road does Edmonton need to maintain? ............................................................. 8

What are the traffic trends in Edmonton that affect potholes? ................................................................... 9

How does the weather in Edmonton affect potholes? ............................................................................... 11

How often do we talk about potholes in Edmonton?................................................................................. 15

What other factors could be considered? .................................................................................................. 17

Sources ........................................................................................................................................................ 18

License......................................................................................................................................................... 18

2


Pothole Primer

Here’s the definition from Wikipedia:

A pothole (sometimes called a kettle and known in parts of the Western United States as a

chuckhole) is a type of disruption in the surface of a roadway where a portion of the road

material has broken away, leaving a hole.

An alternative definition, suggested in “Pothole primer: A public administrator’s guide to understanding

and managing the pothole problem” is:

Any pavement defect involving the surface, or the surface and base, to the extent that it will

cause significant noticeable impact on vehicle tires and vehicle handling.

How do potholes form? Potholes develop when water and traffic are present at the same time. This infographic from the

Missourian illustrates this process:

3


How many potholes are there in Edmonton?

The City of Edmonton generally cites an average of 400,000 potholes filled each year, and in 2012

estimated that roughly 97% of potholes would be filled. The true number of potholes is difficult to

estimate.

This chart shows the number of potholes filled in Edmonton since 2000:

That totals more than 5.6 million potholes! Using an average of 400,000 potholes per year for the period

1990-1999, we can estimate that the City of Edmonton has filled nearly 10 million potholes over the last

20 years.

386,845 354,376

319,873 354,150

404,000

527,450

346,250

593,050

443,300 471,000

434,950

549,600

453,600

-

100,000

200,000

300,000

400,000

500,000

600,000

700,000

2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012

Potholes Filled by Year (2000-2012)

4


How much does Edmonton spend fixing potholes?

A true accounting of the cost of the pothole problem would consider a number of factors, including:

The cost to fill potholes each year

The cost of any preventative maintenance undertaken

The cost of any claims paid out

The cost of repairs to vehicle damage caused due to potholes

Unfortunately, available data on these factors is limited. Estimates for the cost of fixing a pothole range

from $8.00 per pothole to $25.00 per pothole.

The City of Edmonton does provide costing information for repairing, maintaining and reconstructing

roads:

Crack sealing (roads in excellent condition) $1.20/m2 Microsurfacing (roads in excellent condition) $4.50/m2 Resurfacing (roads in fair condition) $23.33/m2 Rehabilitation (roads in fair condition) $79.70/m2 Pothole Repairs (poor condition) $78.77/m2 Reconstruction (very poor condition) $209.00/m2

Here’s a look at the annual amount budgeted by the City of Edmonton to fill potholes:

$-

$1,000,000

$2,000,000

$3,000,000

$4,000,000

$5,000,000

$6,000,000

$7,000,000

Pothole Budget by Year (1990-2013)

5


Since 1990, the City of Edmonton has budgeted an average of $3.5 million per year just for filling

potholes, for a total of about $85 million. After reaching a peak in 1995, the budget for potholes

dropped to less than $3 million per year until the mid-2000s.

Here’s a look at the same data, adjusted for inflation:

Looking at the raw budget numbers, it appears that Edmonton budgeted about the same for the period

1990-1999 as it did for the period 2000-2009. But taking inflation into account, the City actually

budgeted about $8 million less in the latter period.

$-

$1,000,000

$2,000,000

$3,000,000

$4,000,000

$5,000,000

$6,000,000

$7,000,000

$8,000,000

$9,000,000

Pothole Budget by Year Adjusted for Inflation (1990-2013)

6


How does Edmonton compare to other Canadian cities?

Edmonton is one of the few cities that tracks the number of potholes it fills each year, and the only one

that makes that data readily available through its Open Data Catalogue.

Using news articles and other publicly available information, we can get a sense of how Edmonton

compares to other major cities in Canada:

Edmonton fills far more potholes each year than any of its counterparts.

40,000

435,000

50,000

180,000 200,000

40,000

200,000

$-

$1,000,000

$2,000,000

$3,000,000

$4,000,000

$5,000,000

$6,000,000

-

50,000

100,000

150,000

200,000

250,000

300,000

350,000

400,000

450,000

500,000

Calgary Edmonton Montreal Ottawa Toronto Vancouver Winnipeg

Average Annual Number of Potholes Filled vs. Average Annual Budget

7


Using this data we can estimate the amount budgeted per pothole:

While it is hard to make true comparisons across cities, due to differences in the accuracy of the data as

well as the processes and methodologies that each follow, this does give some indication of where

Edmonton lies in relation to other major cities in Canada.

$87.50

$8.51

$50.00

$26.67

$20.00

$11.25 $7.50

$-

$10.00

$20.00

$30.00

$40.00

$50.00

$60.00

$70.00

$80.00

$90.00

$100.00

Calgary Edmonton Montreal Ottawa Toronto Vancouver Winnipeg

Average Annual Budget/Pothole

8


How many kilometers of road does Edmonton need to maintain?

The City of Edmonton currently maintains more than 4,600 kilometers of roads. Here’s a look at the

increases to our road network since 1994:

A measure known as the Pavement Quality Index (PQI) is used to distinguish between roads in poor

condition and those in good condition. A score of 6.5 out of 10 is considered “industry standard” for

quality.

In 1993, a study found that 29% of Edmonton’s arterial and collector roads were in poor condition, while

19% of local roads were in poor condition. In 1995, the City attributed a PQI of 5.4 to arterial roads and

5.2 to collector roads. A report in 2007 warned that these values would drop to 5.2 and 4.4 respectively,

unless funding levels increased.

From the approved 2012-2014 Capital Budget:

The Arterial Road Rehabilitation Program approved budget is only 39 per cent of the minimum $40 million per year required funding levels. The level funding could result in an overall decrease in the Pavement Quality Index (PQI) for arterial roads. As a result of increased investment in 2009-2011, the average PQI for arterial roads is currently 6.1. The reduction in approved funding for this program could result in an overall decrease in the PQI from 6.1 down to 5.1 over the course of the 3-year budget program, resulting in PQI ratings equivalent to that of the mid 1990's. This would present as an increase in the number of potholes and the amount of operational maintenance required.

3900.00

4000.00

4100.00

4200.00

4300.00

4400.00

4500.00

4600.00

4700.00

Length of All Roads Maintained in KM(Edmonton, 1994-2012)

9


What are the traffic trends in Edmonton that affect potholes?

As traffic is one of the two most important factors in the creation of potholes (the other being water) it

may be useful to know more about traffic.

Here’s a look at the number of registered motor vehicles in Edmonton, St. Albert, and Leduc:

Edmonton accounted for roughly 18.9% of all motorized vehicles registered in Alberta in 2012. That’s a

small decline from 2004 when the percentage was 19.3%.

One of the best sources of information on driving habits is the Canadian Vehicle Survey, last updated in

2009. Looking at that data, we can see that the number of kilometers traveled each year in Alberta has

increased to nearly 50 billion.

458,799 470,839 492,886

524,845 554,714 567,745 574,802 585,765 602,783

-

100,000

200,000

300,000

400,000

500,000

600,000

700,000

2004 2005 2006 2007 2008 2009 2010 2011 2012

Number of Registered Motor Vehicles (2004-2012)

EDMONTON ST. ALBERT LEDUC

10


Another factor to consider is the weight of vehicles. While the distance travelled by vehicles in all classes

has gone up 15.3% in Alberta from 2000 to 2009, the largest increase has been in vehicles that weight

more than 4.5 tonnes.

42.1 40.4

37.0 39.4 38.7

44.1 45.5

47.8 47.4 49.7

-

10.0

20.0

30.0

40.0

50.0

60.0

2000 2001 2002 2003 2004 2005 2006 2007 2008 2009

BIL

LIO

NS

Vehicle-Kilometers in Alberta (Total)

13.2%

56.2%

17.2%

0.0%

10.0%

20.0%

30.0%

40.0%

50.0%

60.0%

Vehicles up to 4.5 tonnes Trucks 4.5 tonnes to 14.9 tonnes Trucks 15 tonnes and over

Increase in Annual Vehicle-Kilometers in Alberta(2000-2009)

11


How does the weather in Edmonton affect potholes? Here’s a look at the amount of precipitation recorded per year at the City Centre Airport:

Here’s a look at the difference in extreme temperatures recorded per year:

445

408

375

247

484

519

287

430

272293

244

381 390370

0

100

200

300

400

500

600

1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012

Total Precipitation by Year (mm)

29.1 29.133.5 34.9 33.0 31.2 30.1

35.132.5

35.0 33.531.1 32.5 33.1

-29.2 -27.8-24.4

-29.5-34.0 -35.4

-33.3-28.3 -29.3

-36.0 -36.5

-27.6-30.6 -32.1

-50.0

-40.0

-30.0

-20.0

-10.0

0.0

10.0

20.0

30.0

40.0

1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012

Difference in Extreme Temperatures by Year

Max Temp (°C) Min Temp (°C)

12


It is commonly stated that freeze/thaw cycles contribute to the degradation of road surfaces. Here’s a

look at the number of days per winter (October through March) where a temperature increase from

below zero to above zero was preceded by precipitation.

While there does not seem to be a correlation between the number of potholes (remember 2007 was

the worst year on record) and the number of freeze/thaw days, there are other factors to consider. This

data comes from the City Centre Airport, but temperature and precipitation are not uniform around the

city. There could be large variations in precipitation that make potholes more likely to form in one part

of the city versus another.

9

5

4

12

6

3

5

9 9

13

9 9

6

13

0

2

4

6

8

10

12

14

Winter Days of Freeze/Thaw Preceded by Precipitation

13


Here’s a look at the total amount of precipitation per winter:

Here’s a look at the number of winter days below and above zero degrees:

75.8

34.6

76.2

126.6

90.6

101.3

57.5

68

53.5

6268

78.5

48.5

103

0

20

40

60

80

100

120

140

Total Precipitation by Winter (mm)

0 20 40 60 80 100 120 140 160 180 200

1999-2000

2000-2001

2001-2002

2002-2003

2003-2004

2004-2005

2005-2006

2006-2007

2007-2008

2008-2009

2009-2010

2010-2011

2011-2012

2012-2013

Number of Winter Days Below & Above Zero Degrees (Mean)

Below Zero Days Zero & Above Days

14


Here’s a look at the temperature extremes by winter:

21.9 23.219.1 17.4

27.124.1

19.0 20.225.3 27.1

17.8

23.9

17.720.5

-26.1 -27.8 -29.5-34.0 -35.4

-33.3-28.3 -29.3

-36.0-33.3

-36.5

-30.6 -32.1-28.6

-40.0

-30.0

-20.0

-10.0

0.0

10.0

20.0

30.0

40.0

Difference in Extreme Temperatures by Winter

Max Temp (°C) Min Temp (°C)

15


How often do we talk about potholes in Edmonton?

Here’s a look at the number of Edmonton Journal articles mentioning potholes from 1989 to March of

2013:

The two years with the most articles, 2007 and 2011, are also the two years with the most potholes

filled. The jump in 1992 may be accounted for by the doubling of the pothole budget that year.

32 35

61

81

59 65 5866

87

59 63 6549

69 68

9679

90

275

118104

89

145

45 52

0

50

100

150

200

250

300

Pothole Articles in the Edmonton Journal by Year (1989 - March 2013)

16


Here’s a look at the number of pothole-related tweets posted by Edmontonians from 2009 to 2012.

Unsurprisingly, more tweets are posted in March and April when the snow melts and potholes form and

become visible:

64

281

1078

516

184132 158

104 111 13061 54

0

200

400

600

800

1000

1200

Pothole Tweets by Edmontonians by Month (2009-2012)

17


What other factors could be considered?

There are many other factors that could be considered when examining Edmonton’s pothole problem,

including:

Information about snow removal

Information about drainage and standing water

Information about experiments with materials (asphalt, concrete, polymers, etc.)

Details about the construction criteria for roads over time (thickness, etc.)

Information about road maintenance programs in addition to pothole filling

Further detail about traffic volumes on City streets

Further detail about temperature and precipitation in regions of the City

Data about utility placement and cutting (manhole covers, etc.)

Information about soil

Information about the number of buses and bus stops

18


Sources http://en.wikipedia.org/wiki/Pothole

http://www.crrel.usace.army.mil/library/specialreports/SR81-21.pdf

http://www.columbiamissourian.com/m/24523/how-do-potholes-form/

http://www.calgarysun.com/videos/featured/featured-cal/1213592865001/city-plugs-97-pothole-fill-

rate/1525054990001

https://data.edmonton.ca/Transportation/Potholes-Filled/uytp-iqga

http://www.bankofcanada.ca/rates/related/inflation-calculator/

http://www.edmonton.ca/transportation/road_projects/roads-infrastructure.aspx

http://www.transportation.alberta.ca/Content/docType47/Production/vehreg2008.pdf

http://www.transportation.alberta.ca/Content/docType47/Production/vehreg2012.pdf

http://www5.statcan.gc.ca/bsolc/olc-cel/olc-cel?catno=53-223-X&CHROPG=1&lang=eng

http://climate.weatheroffice.gc.ca/climateData/hourlydata_e.html?timeframe=1&Prov=XX&StationID=1

867&Year=2013&Month=4&Day=

http://climate.weatheroffice.gc.ca/climateData/hourlydata_e.html?timeframe=1&Prov=XX&StationID=3

1427&Year=2013&Month=4&Day=

License http://creativecommons.org/licenses/by-sa/2.5/ca/

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