Transportation Asset Management Case Studies
Economics in Asset Management, The Florida Experience
How Did Hillsborough County Implement its Asset Management Program?
In 1997, the Public Works Department assembled two management teams to launch its Asset Management program, focusing initially on creating comprehensive inventories of the department's infrastructure assets. Three asset categories were defined:
- Roadway: Traffic devices, pavements, markings, lighting, bridge and intersection infrastructure, signals, poles, etc.;
- Road-edge: Sidewalks, shoulders, curbs and gutters, inlets, driveways; and
- Roadside: Stormwater pipes, ditches, vegetation, boundaries, topography.
One team, consisting of Public Works Department staff from its Engineering, Transportation Maintenance, and Traffic Divisions, was charged with establishing the scope of services for contracts to develop inventories of the first two categories (collectively referred to as the "Roadway Asset Inventory"). The department's Engineering Division's Stormwater Management Section was charged with developing a separate scope of services for the stormwater and drainage asset inventory contract (the "Stormwater Asset Inventory").
Establishing the Inventories
The goal for establishing the inventories was not only to number and locate the infrastructure assets, but also to develop a condition assessment for each of these assets. To accomplish this feat, the scopes of services for the roadway and stormwater asset inventories required the use of innovative, state-of-the-art data collection techniques.
For the roadway assets, the department selected a local general contractor and two subcontractors with specialized expertise to collect the data. Using vans equipped with four digital cameras, a global positioning system (GPS) receiver, and an inertial navigation system, the contractor field personnel drove all of Hillsborough County's 3,000 centerline roadway miles in both directions, taking snapshots of roadside attributes every 35 feet to provide 360-degree coverage. This method allowed the contractor team to capture data at traffic speeds. Roadway conditions were assessed based on surface distress, cross slope, roughness, rutting, curb reveal, shoulder dropoff, and deflection. Point assets were precisely located to sub-meter accuracy and data were provided on their condition. Subsequently, the contractors, working with department personnel, identified and catalogued the assets using advanced recognition software and assigned the assets a rating of good, fair, or poor.
The contractor team collected more than 400 gigabytes of photographic data on roadway assets from September 1999 to January 2000. Inventory and condition assessment data were extracted on all of the more than 20,000 miles of linear assets and 500,000 point assets that the department manages.
For the stormwater asset elements, the department contracted with the University of South Florida to collect the data. The university developed protocols that used GPS units and GIS data collectors for field data collection. The university also created the protocols for GIS post-processing for quality assurance and data loading into the department's Asset Management system. Condition data were supplemented by digital images of stormwater assets.
Populating the Asset Management System
The Public Works Department decided to integrate all of the roadway asset data into its existing Hansen Infrastructure Management System Roadway Module and to link this system to its GIS base map. Accordingly, the contractor team was charged with entering the roadway inventory and condition data collected by the mapping vans into the roadway module. The team also entered data from the Florida Department of Transportation's bridge management program.
With data integration completed, personnel can display a county roadway asset's location, ascertain its condition and maintenance history, view its photographs, and update its data.
During 2000, the team successfully incorporated the new data into the roadway module. The team established a link between the mapped data recorded in the roadway module and the county's preexisting GIS base map through a linear referencing system, associating any asset in the GIS base map with an asset key in the roadway module. Newly surveyed assets in the roadway module were incorporated into the GIS base map using a technique called dynamic segmentation. With this data integration effort completed, county personnel can display where the county's roadway assets are located, ascertain their condition and maintenance history, view photographs of the assets, and update the asset data. The referencing system will facilitate future additions to and links with these data as the county expands its Asset Management program.
The University of South Florida developed a Stormwater Atlas from all existing and newly collected stormwater and drainage asset data using GIS software. The university then designed a customized stormwater module/GIS interface that county personnel can use to identify stormwater features, view photographs and attribute data, plot maps, and update the asset data.
Collectively, the linked roadway and stormwater modules and GIS systems form the core of HAMS, incorporating data on all roadway and stormwater infrastructure assets.
Application of Economic Analysis Tools
Hillsborough County began the pursuit of improved information management systems with the goal of making the best possible asset investment decisions. The county recognized that economic analysis tools, combining technical and accounting data, could make a valuable contribution toward this decision-making goal and has actively sought to apply such tools within HAMS or in conjunction with HAMS data.
Assembling the infrastructure asset inventory database was an important step toward the county's comprehensive use of economic analysis techniques. By providing information on asset location, condition, deterioration rate, and dimensions, the database enables analysts to prioritize and anticipate replacement and maintenance needs for many years to come. With the addition of cost and benefit data to this data mix, analysts can use economic analysis tools to determine the best actions to take from the standpoint of lowest overall costs and greatest net benefits to the public.
The department is implementing economic analysis applications in different types of asset decision-making:
- Investment in new projects;
- Minimizing asset life-cycle costs through activities to evaluate and preserve infrastructure and materials; and
- Evaluation of new technologies.
Asset coordinators can now retrieve data from HAMS on pavement condition; road classification (e.g., principal arterial, collector); and quantity, condition, and preservation choices for more than 38 types of road assets.
With regard to program- and project-level investments, the department has implemented benefit-cost analysis as a means of ranking competing intersection and sidewalk investments. The example of benefit-cost analysis of intersection investments illustrates the new economic approach to Asset Management.
Before adopting an Asset Management strategy, the department's method of prioritizing intersection capital improvement projects was ad hoc and largely subjective. County staff would make judgments about the desirability and relative importance of competing projects and consider public and official complaints about traffic operations. To improve accountability and public service, the county has replaced the old process with the Intersections Program Management Information Systems (IPMIS). Under the new methodology, the county prioritizes intersection projects based upon the following benefit-cost ratio formula, applied over the project's life cycle:
|Benefit||=||Present worth (economic benefit of vehicle delay savings + crash reduction savings associated with the improvement + salvage value)|
|Cost||Present worth of cost of the improvement|
Present worth is calculated in dollars over a 20-year timeframe using a 7 percent discount rate to reflect the opportunity cost of money.
Potential intersection projects are initially identified based on the crash numbers and crash rates of all 14,000 intersections. Benefit-cost ratios are then calculated for the top 100 to 150 intersection projects, and the projects are ranked in order of these ratios for selection. Intersection crash data are provided by the Hillsborough County Sheriff 's Office and the Florida Highway Patrol and recorded in the county's accident reporting software system. Traffic data are collected at the intersections to determine potential delay reduction using highway capacity software. The dollar values used for reduced crashes and saved time are based on traffic engineering data and other published sources. Project costing and salvage value are based on data in HAMS and technical and real estate cost estimates. The county plans to integrate IPMIS fully with HAMS in the future.
Life-cycle cost analysis of assets, particularly with regard to extending the life of assets through timely preservation treatments, is greatly facilitated by HAMS. Asset coordinators can retrieve data from HAMS on pavement condition; road classification (e.g., principal arterial, collector); and quantity, condition, and preservation choices for more than 38 types of road assets.
|Treatment||Estimated Life (Years)||Unit Cost per Lane-Mile ($)|
|Ultrathin bonded asphalt||3||34,500|
As an example, the pavement information can be used with a pavement management decision model that guides the analyst through a series of questions regarding roadway condition, traffic, and alternative treatment strategies to determine reasonable treatment strategies. These potential strategies (see table) are further refined based on life-cycle cost criteria, verified against field inspections, and, finally, mapped on the GIS base map to determine the best coordinated treatment for roads in a given area. As a matter of good practice, it is the policy of the department to perform some form of treatment on every road at least once every 7 years.
With regard to the evaluation of new technologies, Hillsborough County recently completed a comprehensive economic evaluation of the cost of replacing incandescent traffic signal lights with LED lights. In addition to the well-documented energy saving, safety, and maintenance life-cycle benefits associated with LED lights, the evaluation also considered the cost of integrating the LED technology into the county's ITS network. The comprehensive accounting of traffic signals in the HAMS database expedited this evaluation. The county has applied similar economic evaluations to its decisions to select various software packages used in the ITS network.
The department will add more economic applications to HAMS data as its experience increases. Its stated goal is to apply a "dollars and cents" criterion to all of its infrastructure decisions.