MPC
Research Projects (2008-09)
Identifying Number
MPC-312
Project Title
A GIS Model for Bridge Management and Routing
University
North Dakota State UniversityProject Investigators
Subhro Mitra, Alan Dybing, Kurt Johnson, and Denver Tolliver
Description of Project Abstract
Including box culverts, North Dakota has over 5,000 bridges located on state and county highways. Many of these bridges have great economic value in the distribution of farm and petroleum products and manufactured goods. In most cases, the closure of a bridge means the closure of a roadway segment. A bridge can be a binding constraint to commercial vehicles traveling a roadway segment because of load limits, narrow lanes, poor approaches, or limiting vertical and horizontal clearances.
North Dakota has implemented the Highway Economic Requirements System, which provides estimates of the benefits of investing in highway pavements. At present, there is no comparable model to estimate the user and economic benefits of bridges. In the future, NDDOT must make difficult decisions about bridge investments. With limited funding and increasing costs, it is important to understand the economic benefits of making these investments.
North Dakota has a statewide GIS highway model that allows the prediction of farm and other commercial truck traffic on individual highway segments. Although bridges are embedded in these links, the GIS network is not completely functional. At present, bridge attributes cannot be used in truck cost and route algorithms. Although North Dakota has routing procedures for oversize vehicles, these procedures are not fully integrated with the GIS highway model.
This project will extend the capabilities of the state GIS model (which has already been used to analyze the economic value of highway pavements and the economic costs of seasonal load restrictions) to explicitly model the characteristics and economic value of bridges to the state’s economy. The results of this project will be: (1) a statewide GIS network of state and county roads in which bridges are explicitly modeled as internal nodes on links, so that bridge characteristics and limitations can be reflected into routing and distribution cost models; (2) an advanced GIS routing tool that can optimize routes for oversize, overweight, and hazmat loads, based on both roadway and bridge characteristics; (3) integration of the REMI regional economic model with the GIS network model so that the total economic benefits of making investments in bridges can be quantified; (4) a statewide analysis of the economic value of bridges to the state’s economy (as well as detailed analyses of individual bridges); (5) improved detour cost estimates for inclusion in the National Bridge Inventory; and (6) integration procedures that will allow data from the National Bridge Inventory and Pontis to be directly accessed from the routing and economic analysis models. The GIS model will improve estimates of detour distances and costs because the model predicts commercial truck flows from origins to destinations. Therefore, the comprehensive (network) effects of bridge limitations and closures can be analyzed.
Project Objective
The immediate research objectives are to: (1) provide a model for routing commercial vehicle movements based on bridge and roadway characteristics; (2) provide improved methods for estimating detour distances, costs, and the economic value of bridges; (3) integrate bridge data sources and models with the statewide GIS highway network model (which will build the capability for future analyses of the effects of infrastructure investments on the petroleum, energy, and agricultural industries); and (4) quantify the total economic value of highway bridges in North Dakota. This last objective is important because it provides the DOT with quantified values that can be used to describe the importance and value of bridges to the state’s economy and traveling public. The long-term objective for the SAFETEA-LU period is to achieve (through a sequence of research projects) a fully functional bridge life-cycle cost and asset management system.
Project Approach/Methods
The initial task includes the completion of a literature review and survey of other states in the region to determine the models and procedures they are currently using. Next, an assessment will be made of available bridge data (including data that are not currently geocoded) which can be linked to the GIS model. This assessment will lead to the identification of necessary origin-destination data. Agricultural production, elevators, and ethanol plants are already represented in the statewide GIS model, as are some oil production and demand locations. However, more detailed destination data is needed in order to model petroleum flows on highways and bridges. Once the origin-destination data have been identified, all of these nodes will be included in the model with updated supply and demand data.
Bridges will be explicitly added to the GIS network. Key bridge attributes (such as geometry, clearances, load limits, etc.) can then be included in routing models. Routing algorithms will be developed using the Cube Transportation Planning software that simultaneously predict commercial trucks flows over the network and assign truck trips to roadway segments and bridges. The predicted flows will be calibrated against observed truck traffic. The impedance functions in the model (which are based on truck cost and distance) will reflect key bridge attributes such as load limit and clearance restrictions. Risk factors for routing hazardous materials will also be considered—such as bridge approaches, narrow lanes, etc. Once the model is built, it can be used to analyze the incremental distances and transportation costs attributable to bridge limitations, as well as the effects of potential bridge closures. It can also be used to identify optimal routes for oversize and overweight loads based on bridges clearances and load limits.
In one of the later tasks, the state GIS model will be linked to the REMI regional economic model. Afterward, the economic value of highway bridges will be quantified. The GIS model will be used to estimate detour costs for all commercial traffic. Detour costs for automobile traffic will be based on traffic count data from the NBI. The incremental vehicle miles and hours of travel will be input to the REMI model to quantify the total economic benefits to the state. These benefits will include productivity gains to industries because of reduced trucking costs and statewide economic benefits because of improved accessibility to the rest of the region and nation.
MPC Critical Issues Addressed by the Research
Economic Analysis of Investments and Impacts (#18). Integrated Asset Management Systems (#19)
Contributions/Potential Applications of Research
The outcome of this proposed project is a comprehensive statewide GIS model that can be used to quantify the economic value of bridges (and the effects of bridge limitations), and provide optimal routes for commercial trucks including oversize, overweight, and hazmat loads. In addition to providing specific capabilities for bridge analysis, this project will improve pavement analysis capabilities by enhancing the GIS model and adding more specific origin-destination data. County and state bridges will be included in the analysis. The project report will quantify the economic value of bridges to the state’s economy for the first time. This is important information in making decisions about future bridge funding levels.
Technology Transfer Activities
The project will further integrate the asset management systems of NDDOT and provide examples that may be useful to other states in the region. The results will be disseminated via the Transportation Learning Network and LTAP Centers in the region.
Time Duration
July 1, 2008-December 31, 2009
Total Project Cost
$139,239
MPC Funds Requested
$90,000
TRB Keywords
Pontis, bridge management, asset management
