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Canadian Consulting Engineer, 43, Jan./Feb. 1, pp. 41-42, 44, 2002-01-01
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Maintenance issues : federal research is being conducted on
infrastructure problems such as road utility cuts and managing large
sewers
Bullis, R.
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Maintenance issues : federal research is being
conducted on infrastructure problems such as road
utility cuts and managing large sewers
Bullis, R.
A version of this paper is published in / Une version de ce document se trouve dans:
Canadian Consulting Engineer, v. 43, no. 1, Jan./Feb. 2002, pp. 41-42, 44
www.nrc.ca/irc/ircpubs
January/February 2002 Canadian Consulting Engineer 41
providers, with h uge cost implica-tion s for both .
IRC research er Dr. El H ussein Mohamed heads a utility cut research project launched by IRC in collabo-ration with th e Cold Region s Research and Engineering Laborato-ry ( CRREL) of the U.S. Army Corps of Engineers and 26 other partners. The partnership list includes cities, state transportation departments and utilities in the U.S. and Canada. The project is in its second year, but new partners are still being invited to join in order to increase the number of experiments carried out.
The project is examining more effective options for reinstating utility cuts, and will develop models to pre-dict how reinstated roads will per-form. The models will provide the basis for a best-practice guide and guide to selecting materials. The researchers will also develop a software tool that will predict the performance of a reinstated road and evaluate alter-native strategies. The ultimate goal is to arm municipalities and utilities with
T
h e main ten an ce of Can ada’s urban in frastructure systems requires huge financial commit-men ts from mun icipalities an d provincial governments. They must make tough decision s ever y day regarding products, services, materi-als, equipment and practices, and they and their consulting engineers are constantly searching for better ways of doing things.Fortunately, the National Research Council’s Institute for Research in Construction (IRC) has a number of co-operative projects giving insights into the causes of infrastructure prob-lems. The research is being carried out in IRC’s Urban Infrastructure Reh abilitation Program. IRC also offers tools to help clients develop cost-effective solutions.
On the surface —
dealing w ith utility cuts
Surveys sh ow th at pavemen t restora-tion followin g un dergroun d work on utilities is a major ch allen ge fac-in g m u n icip alities an d u tilityI
NFRASTRUCTURE
By Rober t Bullis
for Ins t it ut e for Res ear ch in Cons t r uct ion,
N at ional Res ear ch Council
M aintenance Issues
Federal research is being conducted on infrastructure problems
such as road utility cuts and managing large sew ers.
information enabling them to make informed decisions before issuing per-mits and sending contractors out to dig up a street.
To date, four field experiments have been constructed as part of the investigation — in Ottawa, Toronto, Chicago and Los Angeles. As well, IRC and CRREL conducted a North Amer-ica-wide survey of municipalities and utility providers. The survey asked questions about typical road composi-tion, construction procedures and standards, materials and equipment, quality control measures etc. It also touched on management approaches. The results are being analyzed, with the results due May 2003.
For more information, contact Dr. Mohamed at ( 613) 993-3817, e-mail mohamed.hussein@nrc.ca.
A seal in time —
road maintenance
More than two-thirds of Canadian roads fall under municipal jurisdic-tion, notes Dr. Jean-François Masson, IRC researcher. Of those, 90 per cent are in need of immediate repair. Pre-ventive maintenance is the key to delayin g road recon struction , an d sealing cracks as they occur is an increasingly important way to do this. Effective crack sealing can increase pavement service life by 10-20 per cent and save Canadian municipali-Far left: road excavation in Chicago as part of a Canada-U.S. research project on utility cuts.
Left: sensors being installed for research on a partially restored utility cut in the city of Ottaw a. N R C /I R C
42 Canadian Consulting Engineer January/February 2002
I
NFRASTRUCTURE
cont inued fr om page 4 1 ties more than $800 million over the next 20 years.“Effective” is the key word. “As easy and common as the technique is, crack sealing is not being used as effectively as it should,” Dr. Masson says. “Sealan t failure with in th ree years of application is common, and
failures often occur within the first year, usually because of inappropri-ate selection and installation of minappropri-ate- mate-rials — a direct result of inadequate per formance guidelines.”
IRC reviewed the installation of sealant in its publication, Effective Seal-ing of Pavement Cracks in Cold Urban
Environments.While this guide is now used throughout Canada, it left open the issue of sealant selection. Now, in partnership with the Virginia Tech Transportation Institute, IRC is build-ing a consortium to study that issue.
Over several years, the consortium project will develop procedures to measure the aging effects of bitumi-nous sealants, a method to assess sealant performance, a sealant adhe-sion test that takes into account aggre-gate type, and performance guidelines for sealant selection. These guidelines, says Dr. Masson, will help users select sealants based on specific local needs such as climate conditions, thus extending the product’s service life.
To find out more, contact Dr. Mas-son at ( 613) 993-2144, e-mail jean-francois.masson@nrc.ca.
Going underground —
managing large sew ers
The failure of deeply buried large sewer structures (more than 900 mm in diameter) can have enormous con-sequences, both physically and finan-cially. And maintaining these systems can be equally difficult and expensive. A new IRC publication,Guidelines for Condition Assessment and Rehabilitation of Large Sewers, can help municipalities and their consulting engineers more efficiently manage large sewer assets (both flexible and rigid pipes). The publication was written by the IRC research team of Dr. Jack Zhao, Shel-ley McDonald and Dr. Yehuda Kleiner. Like many other IRC research ini-tiatives, says Dr. Zhao, the publication is the product of a collaboration between IRC, government depart-ments and private companies includ-ing R.V. Anderson Associates, Toronto; and M.E. Andrews Associates, Ottawa.Th e systematic assessmen t approach goes beyon d iden tifyin g defects and coding them, to assessing the condition of the structure, its importance to the system, and its reh abilitation requiremen ts. Th e first step in the process is to compile an inventory database of all pipes
44 Canadian Consulting Engineer January/February 2002
sion s about th e reh abilitation approach: do it now, do it within the next five years, or leave it alone. Once the decisions have been made about rehabilitation and required inspec-tion frequency, the pipe or access hole is returned to the database until its next scheduled inspection.
To order Guidelines for Condition Assessment and Rehabilitation of Large Sewers, contact 1RC’s Publication Sales office, 1.800-672-7990, (613) 993-2463.
The sound of running w ater
-locating leaky pipes
Clean, safe drinking water is a precious commodity in today’s world, and deliv-ering huge amounts of it with as little waste as possible is critical. Unfortu-nately, in most water distribution sys-tems, a large amount of water — 20-30 per cent in typical systems, and as high as 50 per cent in older ones — is lost in transit between treatment facilities
and consumers. The major cause of these losses is usually leakage.
Water utilities primarily use acoustic devices to locate leaks, but Dr. Osama Hunaidi, IRC researcher, points out that these devices have limitations, par-ticularly in the detection of leaks in plastic pipes ( increasingly used in water distribution systems), large-diam-eter concrete pipes, or pipes in clay soils or below the water table.
In 1998, IRC researchers partici-pated in a project funded by the American Water Works Association Research Foundation to investigate ways of improving leak detection for plastic pipes. The project produced several improvemen ts to acoustic equipment and practices, and also developed a new leak detection sys-tem called LeakFinder.
LeakFin der calculates a leak’s location based on the time it takes for a sound from a suspected leak to trav-el to two vibration sen sors or h ydroph on es ( un der water micro-ph on es) th at bracket th e leak. It combines the advantages of acoustic detection with the power of a person-al computer: a PC’s soun dboard records and plays back leak signals, and its CPU filters inter fering noise and cross-correlates the location.
Using Windows 2000, NT, 98 or 95, LeakFinder gives field-verified accura-cy on PVC, cast and ductile iron, asbestos cement and large-diameter concrete pipes. It provides an adjustable playback speed for listening to otherwise inaudible low-frequency leak sounds in plastic pipes. It also per-manently stores leak sounds for off-site re-analysis and evaluation. It is easily modified to incorporate hardware and signal processing advances, and can be integrated with commercial off-the-shelf equipment to provide a complete leak detection system.
“LeakFinder’s low cost makes it practical for users who can’t afford existing commercial systems,” says Dr. Hunaidi. For a demonstration of Leak-Finder, visit www.nrc.ca/ irc/ leak/
leak-finder. C C E
and access holes. An impact assess-ment is then carried out using a rat-ing system that considers factors such as location, type of soil, pipe size, bur-ial depth, sewer function and seismic zone. An evaluation of the results gives an overall impact rating for a pipe segment, and these ratings are placed on a map of the sewer system for easy identification of “hot spots.” The impact rating allows munici-palities to determine the most likely locations for problems, and to priori-tize segments for inspection. During the course of the inspections, defects are identified and coded using IRC’s approach to rate their type and severi-ty. The approach recognizes two main types of defect — service or structural — and up to three levels of severity.
The final step is a condition assess-ment based on the impact, structural and service ratings. This condition assessment provides the basis for
