“Like every agency, we’re being pressed to give better estimates, earlier.  Having a customized parametric solution allows us to quickly and more intelligently give an extremely early planning estimate with very little (if anything) actually quantified on the project.   HDR and ExeVision have been extremely responsive in developing this on a very short time line.”

Brad Hofer, 
Assistant Office Director/Location Engineer
Iowa Department of Transportation

iPD Parametric Estimates

  • Joint ExeVision/HDR project

  • Accurately estimate long-range projects and budgets

  • Estimates are representative of project engineer estimates

  • Applies mathematical and statistical models to the agency’s historical data 

  • Uses sophisticated combination of:

    • Parametric Estimating

    • Percentage of Project

    • Composite Items

iPD Parametric Estimates

(PDF, 2 Pages)

iPD Parametric Estimates™ (iPD PE) began as a joint HDR/ExeVision project for the Iowa Department of Transportation, to fulfill IDOT's need to produce more accurate estimates for long-range projects. iPD PE was recently released to the market and is now available for customized implementation at other state transportation agencies.


The application data sheet  offers an overview of the the parametric estimating solution—this webpage provides additional information on the application and functionality, using screenshots to illustrate the high-level process flow.


If you have questions or would like to have a discussion or a demonstration, please contact us.

General Estimate, Suggested Prices & Price Ranges

The general estimate contains a list of bid and non-bid items selected from the state's specification book or entered directly as needed. Long-range projects can be bid more accurately by adding parametric bid items (items containing little detail), percentage of project items, and composite items. Composite items are assembled using various bid items (e.x. road-base, grading, compaction, HMA, etc.) grouped together to create “Composite 64’ Median Interchange Crossover" rather than individual bid items. 

These non-specific, preliminary bid items are calculated by the application using user modifiable item search parameters to identify significant historical data for analysis, then applying pricing ranges and suggestions.  As the long-range project date nears and additional information becomes available for bid items, non-specific items may be replaced with specific bid items to more accurately reflect the current environment and price estimates. Item prices calculated from historical data and regression operations are continually updated to take into account the most current data generated from more recent projects.


Add Items

During the estimate creation process, bid items, non-bid items, parametric items, percentage of project items and composite items may be searched and added to the estimate one-at-a-time or in multiples.     

General Estimate Showing Percentage Based Items

"Percent of Project" items are added to the general estimate and appear as "% of Project" bid items.  The highlighted items above are Level 1 item categories, representing bid items that may be used on the future project.  This category contains related, potential bid items for the project.  For example, if a Level 1 "Mobilization" category were added, Level 2 items for Mobilization might include "Mobilization for Watering" and "Mobilization for Erosion Control", etc. Multiple bid items per category are added based on the estimator not knowing in the early estimating stages, which specific mobilization items will be used in the final estimate and project.   


Based on the established search parameters for the items in the category, the application locates instances of item use in historical data, and using statistical analysis, determines the percentage of use that will be reflected in the project estimate for those items in the category.  As the estimator gains additional information on bid items and identifies the specific bid items that will be used on the project, those items are moved directly into the general estimate as "percentage of project" bid items, and the remaining items in the category that will not impact the estimate are removed. This ongoing process is a  refining of the estimate, moving from general to specific for increasingly accurate estimates as the project date nears. 

Percentage Based Items—Expand Item

As described in the section above—General Estimate Showing Percentage Based Items—percentage based items can be grouped and arranged in levels, up to six deep.  By clicking on a Level 1 item category in the general estimate, the item category expands to reveal the level structure and the bid items within each level.  As the estimator gains additional information on the project and has a better understanding of which specific items to include in the general estimate, clicking the "Include" box and "OK" moves those bid items to the estimate as "Percent of Project" bid items, as described in the section above.

Parametric Bid Items

A parametric item (e.g. bridge, roadway, etc.), may be added to an estimate when few specific details are known about the project. For example, if a bridge is included on a 5-year plan but little is known about the composition of the deck, materials for the substructure or superstructure, approaches, piers, landscaping, etc., a fairly accurate estimate is still possible with the square footage of the deck as the only known variable.


In the estimate above, the highlighted row is a parametric bridge item that has been added.  As a long-range project, few construction details about the bridge are available.  But using the established search parameters, the analysis identifies representative historical projects and the items within those projects that have been shown to most likely impact the creation of an accurate estimate for a bridge. From that information, iPD Parametric Estimates calculates a projected cost for the parametric items.  As shown in the Percentage Based Items section above, additional supporting project categories (e.g. roadway approaches, landscaping, signage, etc.) are also identified and included as Percentage of Project categories and their item prices and category totals are automatically calculated based on the historical project data analysis, as a percentage of the total project cost.

Composite Items and Components

A Composite Item is a group of  two or more bid items (i.e, components), that is reusable as a single item, and also has value as a template.  The image above shows a "Right Turn Lane" component highlighted in red.  By clicking on the item, the bid items or components that make up that composite item are displayed.  Composite items may be applied repeatedly to an estimate as is, or the bid items in an instance of the applied composite item can be modified as required.  For estimating, the software application will group all identical bid items that exist in the general estimate, either as individual bid items or components within a composite item, and perform statistical analysis from historical data to provide an accurate cost estimate.

Item Trend Lookup Filter

As mentioned in previous sections, the iPD Parametric Estimates application  uses lookup filter parameters to locate appropriate items within historical project data. These items are then included in the statistical analysis to determine the significance and estimate impact each item has.  The "Percentage of Project", "Parametric Item" and bid item costs are calculated based on the regression analysis of the identified "significant" items and their data points.


Filter parameters are set as system defaults or may be modified for each individual item by clicking on that item and modifying parameters such as location, work type, size, time of year, etc. 

If you would like additional information from HDR and ExeVision on Parametric Estimating, please feel free to contact us.