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Cost Effective Drainage Structures
Henry J. “Hank” Gottschalk, IIITechnical Resources Engineer
Virginia Concrete Conference
March 2010
Financial Assessment of Drainage Structure
Cost of supply
Bridge Systems
Culverts
Pipes
Drainage Inlets
Our only limitation is our customers’ imagination.Our only limitation is our customers’ imagination.
Horizontal Structures
Conduit
Structure
Purpose of vertical structure
Connect pipes
Purpose of vertical structure
Connect pipes
Provide access
Purpose of vertical structure
Connect pipes
Provide access
ASCE Photo Contest
Purpose of vertical structure
Connect pipes
Provide access
Shape
Round Vertical Structure
Round Vertical Structure
As = 0.0025 x D(in)
Round Vertical Structure
Rectangular Vertical Structure
Rectangular Vertical Structure
Rectangular Vertical Structure
Rectangular Vertical Structure
Financial Assessment of Drainage Structure
Cost of supply
Cost of proper installation & inspection
Highway Congestion
Congestion robs our nation of productivity and quality of life
– 3.5 billion hours/year time delay
– 5.7 billion gallons of wasted gas/year
– Total cost of $75 billion for the 75 urban areas
2010 FHWA Presentation - Reggie Holt, Sr. Bridge Engineer
Work Zone Safety
Continued need for Accelerated Construction and methods to close fewer lanes
TRB DCG Critical & Cross Cutting Issues, 01-14-11
Work Zone Safety
As many as 1000 fatalities occur each year in roadway construction work zones
TRB DCG Critical & Cross Cutting Issues, 01-14-11
Financial Assessment of Drainage Structure
Cost of supply
Cost of proper installation & inspection
Financial Assessment of Drainage Structure
Cost of supply
Cost of proper installation & inspection
Maintenance
Financial Assessment of Drainage Structure
Cost of supply
Cost of proper installation & inspection
Maintenance
Service Life versus Project Life
U.S. Army Corps of EngineersNo. 1110-2-2902 Engineering and DesignConduits, Culverts, and Pipes (31 March 1998)
(1) CONCRETE- Most studies estimated product service life for concrete pipe to be between 70 and 100 years. Of nine state highway departments, three listed the life as 100 years, five states stated between 70 and 100 years, and one state gave 50 years.
(2) STEEL - Corrugated steel pipe usually fails due to corrosion of the invert or the exterior of the pipe. Properly applied coatings can extend the product life to at least 50 years for most environments.
(3) ALUMINUM- Aluminum pipe is usually affected more by soil-side corrosion than by corrosion of the invert. Long-term performance is difficult to predict because of a relatively short history of use, but the designer should not expect a product service life of greater than 50 years.
(4) PLASTIC- Many different materials fall under the general category of plastic. Each of these materials may have some unique applications where it is suitable or unsuitable. Performance history of plastic pipe is limited. A designer should not expect a product service life of greater than 50 years.
Excerpt from Para. 1-4Life Cycle Design
Risk Assessment
Risk Assessment
Modes of Failure
72” Culvert Failure
Cost = Up to$500,000
Major Highway CLOSED
Business ProfitDecrease
Detour
Longer Employee Commute
Public DrivingConfusion
Officials Manning Roadblocks
The Economic Cost of Culvert Failure
User Delay Costs (Indirect Costs)
Joseph Perrin’s Research:
D = AADT * t * d *(cv * vv * vof + cf * vf)
Where:
AADT = Annual Average Daily Traffic of the roadway which the culvert is being installed
t = the average increase in delay or congestion the installation is causing to each vehicle per day, in hours
d = the number of days the project will takecv = the average rate of person-delay, in dollars per hour vv = the percentage of passenger vehicles traffic vof = the vehicle occupancy factor cf = the average rate of freight-delay, in dollars per hourvf = the percentage of truck traffic
User Delay Costs (Indirect Costs)
Average Established Delay Costs as of 2005, in Dollars:
cv = $18.62 per person / hour of delay
cf = $52.86 per freight /hour of delay
Typical Traffic Assumptions:
vv = 97% vehicle passenger traffic
vf = 3% truck traffic
vof =1.2 persons per vehicle
A one-hour delay on a roadway carrying an Annual Average Daily Traffic of 20,000 vehicles costs the public over $450,000 every day.
Risk Assessment
Modes of Failure
Financial Assessment of Drainage Structure
Cost of supply
Cost of proper installation & inspection
Maintenance
Service Life versus Project Life
It is unwise to pay too much, but it is worse to pay too little.
When you pay too much, you lose a little money.
When you pay too little, you sometimes lose everything, because the thing you bought was incapable of doing the thing it was bought to do.
JOHN RUSKIN 1819-1900, renowned English critic, social commentator, and economist of the Victorian Age
Advantages ofPrecast Concrete Structures
Cast and Cured in a Quality Controlled Environment
Shows up at the Jobsite as a Structure
Strength is All Ready “Built In”Just Set, Connect… and Go!
Save Time & Money! Precast Concrete = Long Service Life
