Presentation on theme: "Pavement Type Selection (Designs, Costs & Bidding) 9 th Annual Concrete Conference for the Maryland Transportation Industry March 24, 2009 Timonium, MD."— Presentation transcript:
Pavement Type Selection (Designs, Costs & Bidding) 9 th Annual Concrete Conference for the Maryland Transportation Industry March 24, 2009 Timonium, MD Presented by Bob Long American Concrete Pavement Association Mid-Atlantic Chapter
Pavement Type Selection Evolution of the Process Good old days More responsible More structured Let the market dictate
What are equivalent sections? Traffic Reliability Subgrade Terminal Condition Traffic Reliability Subgrade Terminal Condition = Provide reasonably similar level of service Designed with the same procedure Same structural capacity Similar traffic-carrying capacity over the analysis period Equivalent Designs
Different Pavement Types Subbase Subgrade Subbase Subgrade Base Asphalt Layer Concrete SectionAsphalt Section
How Pavements Carry Loads 3000 kg. pressure < 0.2 MPa pressure 2.0 MPa Concrete’s Rigidness spreads the load over a large area and keeps pressures on the subgrade low.
Costs Accurate estimates are essential Take into account volume, production, and availability of materials Update regularly
Costs Liquid AC index jumped from $340 to $842 per ton in just over 4 months (April—August 2009) – that’s a $25 per ton increase for in-place asphalt pavement Availability of liquid AC was becoming a concern Over the last 2 years, the price of asphalt pavement has jumped from about $55 to over $75 and as high as $130 per ton Although cement prices did rise for a while before the big AC increases, prices are lower and stable
Economic procedure –That uses Engineering inputs Compares competing alternates over their life –by considering all significant costs (and benefits) Construction, Maintenance, Rehabilitation User Performance Expressed in equivalent dollars What is it ? Life-Cycle Cost Analysis
A Magical Black Box –There is no concrete LCCA or asphalt LCCA Complicated –Does not need a computer program What it is Not Life-Cycle Cost Analysis
Present Worth Analysis (PW) Equivalent Uniform Annual Cost Analysis (EUAC) How it is done: Life-Cycle Cost Analysis
Present Worth Analysis: Discounts all future costs (benefits) to the present Costs Initial Cost Rehabilitation Cost Maintenance Cost Salvage Value Years Costs Present Worth Years Life-Cycle Cost Analysis
Normally equal for each alternative –Highway: 30-50 years –Street: 20-30 years –Airport: 30 years Include at least one rehabilitation –Needed to capture the true economic benefit of each alternate Analysis Period: Life-Cycle Cost Analysis
Delay-of-use –Time delays - New construction & Rehabilitation –Fuel consumption –Driver discomfort Roadway deterioration –Cargo damage –Vehicle wear Accidents User Costs: Life-Cycle Cost Analysis
Cons –Cannot recoup costs –Not in budget (not “real” money) –Drives the results Pros –User fees collected pay for public transportation investments –Drives the results User Costs: Life-Cycle Cost Analysis
Some basic insights: Initial Costs –Account for about 65-90% of Life Cycle Cost. –Selection of features plays an important role –Need to account for added features on the pavement performance. Timing of Activities. –After initial costs and discount rate, the next most important factor. –The longer an activity is delayed, the greater it is discounted and the less impact it has on present worth. Life-Cycle Cost Analysis
LCCA Process Design equivalent pavement sections Establish strategies for analysis period –Estimate agency costs –Establish activity timing –Develop expenditure streams Estimate user costs Compute NPV Analyze results Re-evaluate strategies
Pavement Type Selection Overview of Maryland Process Policy on application of process Three tiered approach –Life cycle cost comparison –Component analysis –Innovative contracting Probabilistic approach to LCC Weighting of component factors based on project priorities Project team formed to make final decision
Application Policy All projects developed through the Project Planning Division ready for design, and Any projects with a construction estimate > $15 million (with at least $5 million dedicated to pavement/MOT items) Estimated to be 6 to 8 projects per year. (Staff resource levels were a limiting factor in the number of projects that could be identified.)
Three Tiered Approach 1st Tier – LCC Analysis within 20% Initial Cost Future Rehab Costs over 40 Years User Delay Costs 2nd Tier – Component Analysis Cost Factors Construction Factors Design & Environment Factors Form Team and Consider Industry Input 3rd Tier – Innovative Contracting Alternate Bidding Warranty Contract Design/Build Contact
Life Cycle Cost Factors Based on historical data and expert opinion –Material unit costs –Pavement service life –Construction sequencing –Construction duration –General analysis inputs Variability represented by average and standard deviation
Component Analysis Cost Factors –Present worth Agency Costs – Initial & Future –Present worth User Delay Costs Construction Factors –Duration of Construction –Maintenance of Traffic –Maintenance of Access –(utilities & future maint, material sources, reliability of construction) Design and Environment Factors –Traffic and Geometry –Adjacent Pavement and Structures –Environmental Impact –(community concerns, future planning)
Project Level PTST Chief Engineer for MDSHA Operations. District Engineer of MDSHA District that project resides. Director of Highway Development (OHD) for MDSHA. Director of Materials & Technology (OMT) for MDSHA. Pavement Division Chief of OMT for MDSHA.
Alternate Pavement Bidding Alternate pavement bidding involves the bidding of two equivalent pavement designs in order to determine the most economical solution to the owner.
Use of Alternate Bidding FHWA traditionally discouraged use of alternate bids for pavements FHWA approved a Special Experimental Project for use of alternate bids in Missouri 1996. AASHTO recognizes Alternate Bids as a contracting technique that will be utilized in the 21 st century Recommended when more than one alternate is judged “equal” by an agency and that the least costly design approach will result from a competitive bid. Alternate bidding should be used when there is no clear cut choice between two alternates and have similar life cycle costs
Use of Alternate Bidding Federal Aid policy suggests that alternative designs are considered for large projects A life cycle cost economic analysis should be conducted to compare the total cost of each alternate. If the alternates do not provide equivalent designs then an adjustment must be made to the bid to equate the alternates. Pavements should be bid in the same units and materials costs escalators should not be used.
Use of Alternate Bidding The following States/Provinces have experience with alternative bidding: –Alabama –Kansas –Kentucky –Louisiana –Maryland –Michigan –Missouri –Ohio –Pennsylvania –West Virginia
Alternate Pavement Bidding Key Steps and Issues for an Alternate Pavement Bid (APB) Process: Establish Pavement Type Selection Team Determine Suitability of Project for APB Establish Performance Standards Determine Type of Work Establish Equivalent Pavement Designs Define LCCA Requirements Account for Bid Adjustment Method
Alternate Pavement Bidding Account for Bid Adjustment Method A + B A + B + C C is usually a product of the following example: C = User Delay Cost + (periodic) Rehab Cost + Annual Maintenance Cost C is added to the actual bid amount
West Virginia’s Alternate Bids Three projects so far with 3 more coming this year No C factor so far First project went asphalt Next two went concrete with the concrete bid 10% less than asphalt WV is getting the lowest unit prices for asphalt they seen in years
Available Software AASHTO DARWIN design WinPAS (ACPA’s Windows version of DARWIN) Mechanistic Empirical Pavement Design Guide (MEPGD – coming soon) RealCosts (LCCA) Concrete Pavement Analyst (NRMCA parking lot design and cost analysis program)
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