Transportation Asset Management Case Studies
Bridge Management Experiences of California, Florida, and South Dakota
The South Dakota Department of Transportation (SDDOT), under the guidance of the South Dakota Bureau of Information and Technology, adopted the Pontis® Bridge Management System to manage their bridge inventory. Pontis® software can be used with either an Oracle database or Sybase® ASA Adaptive Server Anywhere SQL client-server database. SDDOT has chosen to use Sybase® and Powersoft Infomaker® to generate reports and forms.
SDDOT has customized Pontis® with data input screens (figure 12) that allow for entering of more data items than those required by the FHWA NBI translator. Key customization features include
- Six tables for roadway, structure unit, inspection information, substructure items, and accident data associated with bridges
- Forms for data entry
- New structure lists built around SDDOT's business practices
- Database security measures
- Data transfer techniques using Pontis® Data Interchange (PDI)
- Pontis® check-out/check-in quality assurance procedures
- Modified reports
|Figure 12. Customized form for bridge data.|
SDDOT's bridge inventory data are valuable to a number of South Dakota State agencies. For example, the State Department of Agriculture uses the inventory and appraisal information to plan and locate new ethanol plants. The inventory shows which bridges are on the proposed routes and whether the existing bridges are posted for load limits. The State Historical Office has used the inventory information to locate historic structures in South Dakota.
SDDOT inspects bridges using the AASHTO CoRe elements and some custom developed elements. For example, a precast culvert is added to track cast-in-place versus precast concrete culverts. SDDOT uses the FHWA NBI translator to create the NBI ratings for deck, superstructure, substructure, and culverts. State inspectors are responsible for inspection data at the element level and for running the NBI translator, while Central Office personnel are responsible for inventory, appraisal, and load rating information. Consultants performing bridge inspections for local governments are responsible for inventory, appraisal, inspection data, and load rating information.
SDDOT saved approximately 900 man-hours per year in labor by customizing the Pontis® check-out/check-in process. The initial practice was to enter inspection data from paper forms. The objective of this customization was to accomplish both State and non-State electronic inspections according to SDDOT business rules. For instance, the customization allows SDDOT to limit only one bridge inspection to be checked-in and only certain data fields to be updated from the checked out database into their master database. They use this feature extensively throughout the year, as on average 2,000 bridges are checked out to consultants performing local government bridge inspections.
Like Caltrans, SDDOT maintains only the State-owned structures, which total 1,811 and consist of 1,298 bridges and 513 culverts. The 4,062 structures owned by local governments include 3,469 bridges and 593 culverts. Like most States, a majority of the bridges in the South Dakota State system were built during the interstate era of the 1960s. Over 50 percent are reinforced concrete bridges, and about 36 percent are steel girder bridges, whereas for deck area, only 35 percent is reinforced concrete and 50 percent is steel girders (figure 13). Because the goal is to preserve these aging structures, SDDOT finds Pontis® a valuable tool because it calculates the individual rates of deterioration for all the various materials.
|Figure 13. Material type by number of bridges (left) and by deck area (right).|
During 2002 and 2003, SDDOT used Pontis® to begin setting up improvement models based on established policies and standards. Efforts in developing the preservation policy were concentrated on the most common elements in the inventory and the type of preservation work most commonly performed, namely,
- Deck treatments such as epoxy chip seal overlays
- Low slump dense concrete overlays
- Membrane and asphalt overlays
- Waterproofing joints
- Bridge rail modifications
- Steel fatigue retrofits
- Approach slabs and approach modifications
SDDOT recognized the efficiency of programming Pontis® for the most prevalent elements first, and in time, it plans to continue programming to cover policies for all NBI elements. The deterioration calculations were initially based on expert elicitations, and it is expected that as more element-level inspection data are collected, the historical data will supersede the expert elicitations. In other words, Pontis® has the capability of "learning" from the inspection information that is input every 2 years. Pontis® learns how different materials deteriorate at different rates and can thus modify repair and replacement policies. After, say, six inspection cycles, Pontis® can predict policies over a 20-year cycle.
The cost calculations for element actions in the preservation policy are based on using average bid prices from previous years' projects. SDDOT bridge management personnel ensure that the bid item quantity units are in the same format as defined element quantities in Pontis®. An example of cost calculation for low slump dense concrete (LSDC) overlay for a bridge deck in condition state 3 is illustrated in figure 14, where it is seen that the unit costs for decks in condition states 4 and 5 reflect the additional costs needed for removal, preparation, and new material. Pontis® calculates each condition as a separate and independent element.
|Bridge Bid Item||Quantity||Units||Avg. Bid Cost
|Bridge Elevation Survey||1||Lump Sum||$942.00||$942.00|
|LSDC Bridge Deck Overlay||22.3||Cu Yd||$285.98||$6,377.35|
|Concrete Removal Type 1A||297.7||Sq Yd||$17.45||$5,194.87|
|Concrete Removal Type 2A||73.5||Sq Yd||$3.50||$257.25|
|Concrete Removal Type 1B||29.4||Sq Yd||$70.15||$2,062.41|
|Concrete Removal Type 1C||14.7||Sq Yd||$55.98||$822.91|
|Concrete Removal Type 1D||14.7||Sq Yd||$62.53||$919.19|
|Concrete Removal Type B||10||Ft||$8.29||$82.90|
|Class A45 Concrete Fill||3.9||Cu Yd||$180.50||$703.95|
|Finishing and Curing||294||Sq Yd||$39.25||$11,539.50|
|Total LSDC cost =||$28,902.33|
|Total deck area =||$297.7/Sq Yd|
$97 Per Sq Yd
$11 Per Sq Ft
$116 Per Sq M
As part of developing its preservation policy, SDDOT must define failure cost for each element in its environment. SDDOT has adopted the approach of letting Pontis® calculate the minimum failure cost for each element and adding a 10 percent increase to derive the revised failure costs. This formula is used to force Pontis® to trigger a definite action in the worst condition state for an element, rather than defaulting to the "Do Nothing" option.
SDDOT uses Pontis® to recommend bridge projects for its 5-year Surface Transportation Improvement Program. The bridge simulation in Pontis® allows the following three categories of projects, and further customization is possible if needed:
- Inspector-generated work candidate projects
- Projects that are part of long-range programs
- Projects generated by Pontis® based on incremental cost-benefit ratio
The first list generated is then reviewed and re-scoped to include indirect costs (e.g., mobilization, traffic control, contingencies, preliminary and construction engineering) and is rerun through the program simulation (figure 15). The revised list is then ranked manually by SDDOT personnel based on engineering judgment. Like Caltrans, SDDOT's use of Pontis® helps SDDOT achieve its performance measure of reducing the number of structurally deficient bridges and improving the overall health index at the network level.
|Figure 15. Sample programmed list.|
Because of efficiencies it has gained using Pontis®, SDDOT has been able to go to the next level of bridge management, embarking on a project called Concept to Contract (C2C). C2C incorporates all management systems into the new State Transportation Improvement Program (figure 16).
|Figure 16. C2C concept.|
C2C includes the following subsystems:
- Maintain Candidate is a consolidated database containing South Dakota's highway system needs.
- Scoping and Estimating identifies alternatives for specific work to be done on a project and its cost.
- Scheduling and Task Management identifies the tasks to be completed prior to bidding, and by whom.
- Funding identifies what funding to be used on what projects and when to use it.
- Bid Letting allows preparation of bidding documents and electronic interaction with contractors.
Through the C2C program, SDDOT envisions having several computer programs working together as a system to share common information that is part of a highway construction project. It is anticipated that the information will follow the life of the construction project from conception to the time it is advertised for construction.