Tradeoff between Urban Infrastructure and Amenities: City of Hamilton Storm Sewer Upgrades

1
Trade-off between Urban Infrastructure and
Amenities City of Hamilton Storm Sewer Upgrades
During the summers of 2004, 2005, and 2006, Lower
East End Hamilton was at the center of four major
rainfall events that led to a high volume of
reported sewer back-up in residential basements.
An Independent Community Panel identified a
number of factors that contributed to the floods
including the obsolete design of the combined
sanitary/stormwater sewer system. As part of the
Citys response to the flooding events, a sewer
reconstruction project is underway on Edgemont
Street North. An unfortunate consequence of the
reconstruction project is the removal of mature
public street-side trees.
Results
Literature Review
What is the breakpoint in the trade-off between
mature public street-side trees and sewer upgrade
construction?
Of the 296 delivered mail-back questionnaires, 60
were valid, 6 were out of scope (respondents
were not in the target population), and 230 were
refusals. In the end, the response rate was
calculated at 20.7. According to the table
below, the aesthetic, economic, and ecosystem
services indices of tree value were highly
interrelated providing evidence for the existence
of the TA construct. The FRP components, on the
other hand, were not correlated.
The central notion of the studys conceptual
framework is value judgment which is governed by
a social theory of value from the fields of
philosophy, behavioural science and economics.
The value judgment linked to the trade-off
between sewer upgrades and trees should reflect
differences in FRP and TA. FRP is closely related
to flood experience and is conceptualized as a
combination of recurrence perceptions and flood
prevention beliefs. Experience of flooding has
been shown to be positively correlated with
perceptions of flood risk (Siegrist Gutscher,
2006). TA is a combination of the aesthetic,
economic, and ecosystem service value of trees.
Trees have been shown to be both intrinsically
and extrinsically valuable they increase quality
of life (Bolund Hunhammar,1999) as well as
property values (Tyrvainen, 1997). Studies
comparing urban infrastructure and amenities
often focus on economic indicators of value. In a
Boston case study, it was found that proximity to
parks increases property value while proximity to
highways decreases it (Tajima, 2003).
Hypothesis
Lower East End Hamilton residents value sewer
upgrade construction more than mature public
street-side trees. The trade-off breakpoint
between street-side trees and sewer upgrades will
be affected by both Tree Appreciation (TA) and
Flood Risk Perception (FRP). The FRP criteria
will be better predictors of the trade-off
breakpoint between trees and sewer upgrades than
the TA indicators.
Methods
The table of results below shows that, overall,
respondents demonstrated high levels of both TA
and FRP. This gives rise to response-set issues
that are likely associated with a self-relevance
response bias and sampling errors due to an
incomplete flood experience data set. Due to the
small sample size, the frequency data could not
be analyzed. Few respondents reported that trees
are more valuable than sewer upgrades. The 7
people who did tended to score high on TA and FRP
indices. PFE did not show differences in the
trees preferred category. According to the
correlation values, it would seem that TA
indicators of extrinsic value and PFE are
interrelated with the trade-off breakpoint.
A cross-sectional case study of Lower East End
Hamilton was carried out. Data collection was
done using a 44-item mail-back questionnaire. The
items were intended to uncover the respondents
personal experiences with flooding, their
perceptions of flood risk, their level of tree
appreciation, and their valuation of urban
infrastructure and amenities. A total of 300
households, 100 households per sampling group,
were randomly selected from the study site. The
study site was City of Hamilton Ward 4, more
specifically census tracts 054 and 055. These
censuses show similarities in terms of economic
indicators, population composition, and
education. Census tract 054 had the heaviest
concentration of reported sewage back-up and
encompasses the Edgemont Street North Case Group
and the High Flood Experience Contrast Group. The
adjacent census tract (055) has reported
significantly less instances of sewage back-up
and is the site of the Low Flood Experience
Contrast Group.
Purpose
The purpose of this study is to assess the
implicit valuation of urban features using a
methodological approach based on qualitative
data. The evaluation will rely on the comparison
of Lower East End Hamilton residents valuation
of trees as compared to sewer upgrades. We will
also be examining the effects of FRP and TA on
the trade-off break point between public
street-side trees and sewer upgrade construction.
Census Tract 055
Census Tract 054
Contribution
Low Flood Experience Contrast Group
Case Group
Im proposing to look at tree valuation in a more
complex and broad context than past research.
Ill be comparing the value of trees directly to
the value of sewer upgrades. This will be done
for residents with a range of different
experiences with both flood and tree removal.
This type of comparative valuation of urban
features could be very useful for urban planners,
private developers, municipal decision-makers,
etc. Another element of my research is the
importance of TA and FRP for determining the
trade-off breakpoint between sewer upgrades and
street-side trees. This research will not only
uncover whether these hypothesized constructs are
valid but also determine their role in the
valuation process of urban features.
High Flood Experience Contrast Group
Conclusion
As hypothesized, Lower East End Hamilton
residents favour sewer upgrades to street-side
trees. The results seem to support the TA
construct but not the FRP construct. The sample
size was too small to detect differences in the
frequency data, therefore, the influence of TA
and FRP on the trade-off breakpoint could not be
determined. However, the data seems to suggest
that indicators of the extrinsic value of trees
have better predictive value for respondents
scoring in the trees preferred side of the
trade-off breakpoint than PFE.
July 2005 Flooding Calls
2006 Flooding Calls
August 2005 Flooding Calls
Cited References Bolund, P., Hunhammar, S.
(1999). Ecosystem services in urban areas.
Ecological Economics, 29(2), 293-301. Siegrist,
M., Gutscher, H. (2006). Flooding risks A
comparison of lay people's perceptions and
expert's assessments in Switzerland. Risk
Analysis, 26(4), 971-979. Tajima, K. (2003). New
estimates of the demand for urban green space
Implications for valuing the environmental
benefits of Boston's big dig project. Journal of
Urban Affairs, 25(5), 641-655. Tyrvainen, L.
(1997). The amenity value of the urban forest An
application of the hedonic pricing method.
Landscape and Urban Planning, 37(3-4), 211-222.
July 2005 2006 Flooding
August 2005 2006 Flooding
All three floodings
Descriptive statistics were used to depict the
general response tendencies. In some cases, item
responses were cross-tabulated and compared using
chi-square tests. Finally, in order to test the
reliability of the indices and the relationships
between items, Spearman Rho coefficents were
generated. Additional information was gathered
using various sources of information such as
census data, a key informant interview, a public
information session and various City of Hamilton
documents including memorandums, letters to
residents, maps of flooded areas, public meeting
minutes, implementation project reports, and
policy documents.
Presented by Karine Lavergne Department of
Environment Resource Studies, University of
Waterloo klavergn_at_fes.uwaterloo.ca