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1 The objective of this synthesis is to document how transportation agencies use weigh- in-motion (WIM) data for asset design and management, weight enforcement, and freight logistics. The study identifies the use of WIM data as a tool to support decision making. Information was gathered through a literature review, a survey of departments of trans- portation (DOTs), and interviews with selected agencies for case examples. The synthesis also documents impediments to using WIM data as a tool, knowledge gaps, and the research areas with the most potential to address those knowledge gaps. The survey request was sent to all 50 state DOTs in the United States, 6 Canadian provin- cial DOTs, and the New York City DOT (NYCDOT). The U.S. state DOT response rate was 90%, with 45 of the 50 DOTs responding. The survey asked about equipment, calibration, quality control, uses of WIM data (encompassing both standard and innovative applications), identification of WIM data users, and impediments to the use of WIM data. The following analysis is based on the survey responses: â¢ Most agencies (96%) collect or have collected WIM data. â¢ Agencies have a wide range of equipment types, and many have periodic problems with equipment (sensors and data quality). â¢ WIM systems are costly, and some agencies see funding for installing and maintaining these systems as a constraint to using WIM data within the DOT. Funding for installation is easier to justify than the continued funding for maintenance and calibration. â¢ Many agencies use WIM data to aid in pavement design, although most are not currently using a mechanisticâempirical pavement design application (e.g., AASHTOWare Pavement ME Design software). â¢ A much smaller number of DOTs use WIM data for bridge design and asset management purposes. â¢ Agencies willingly share their data within their organization and with others that request the data. â¢ One impediment to sharing data is that people who might use the data either do not know they exist or do not see a benefit from using them. Using a number of different criteria, the California DOT (Caltrans), Minnesota DOT (MnDOT), Florida DOT (FDOT), Maryland DOT, and Tennessee DOT (TDOT) were S U M M A R Y Use of Weigh-in-Motion Data for Pavement, Bridge, Weight Enforcement, and Freight Logistics Applications
2 Use of Weigh-in-Motion Data for Pavement, Bridge, Weight Enforcement, and Freight Logistics Applications selected for case example follow-up interviews. Following are the most salient points from this effort: â¢ These agencies include the time needed for installation and maintenance in their choice of sensor types. The time needed for lane closure can drive the sensor type selection. â¢ More DOTs are contracting for maintenance and calibration services for WIM systems and considering pay-for-data solutions due to funding and personnel concerns, and dwindling expertise at DOTs. â¢ Three of the five agencies are working toward implementation of the American Asso- ciation of State Highway Transportation Officials (AASHTO) Mechanistic-Empirical Pavement Design Guide (MEPDG) in some capacity, but the others are staying with using previous pavement design methods that use equivalent single axle load (ESAL) calculations. â¢ Only two of the five DOTs indicated that agency Bridge Design personnel have used WIM data for bridge design (according to the interview or a survey question), and these are only in a few special high truck volume locationsânot for standard bridges. â¢ Although only one agency is actively using WIM data for freight planning purposes, others are interested in or partially using some data in this way. â¢ One agency indicated there may be opportunities to augment or even supplant WIM data with purchased freight and commodity data available from data aggregation and analytics (Big Data) companies. â¢ Several of these states are working on initiatives for innovative calibration, using exist- ing data in new ways, or collecting classification data in other, less costly ways than using WIM stations. Based on all components of this synthesis, the impediments to using WIM data as a tool are documented below, along with knowledge gaps and the research areas that can address those gaps. Identified impediments to using WIM are technology-based, funding-based, or internal to an organization. These are some of the findings. â¢ WIM systems are costly; recognizing this, some agencies try to augment their network with less costly data collection devices. â¢ To obtain useful data, agencies need a sufficiently large WIM network, with enough stations. Securing the funding for both installation of new WIM stations and mainte- nance of existing stations is seen as a constraint to acquiring useful data. â¢ DOT staff collecting WIM data are sometimes unsure what is done with the data by others in the agency, and the DOT staff who could use the data do not know the data are available or how the data could help them. In the future DOTs may need more WIM data and more types of data than are currently being collected. Additionally, other ways to acquire and use the data may develop. Below are some knowledge gaps that merit future study, discussion, and research. â¢ Many DOTs are looking for ways to optimize WIM calibration, which is a costly and time-consuming activity. More research is needed to help DOTs optimize calibration procedures and automate the process to include the concepts of pairing WIM and static scale or on-board weight sensor information. â¢ DOTs are concerned that their WIM network is not able to assess the transportation network adequately. Some DOTs are working to expand their network and others are redeveloping networks. Research is needed to help DOTs determine the optimal number and location of WIM stations in their state to better represent the infrastruc- ture use.
Summary 3 â¢ DOT staff collecting WIM data are sometimes unsure of the use of the data by others in the agency. Additionally, the DOT staff that could use the data do not know the extent and accuracy of the data available to them. Research is needed to bridge this gap and help various areas in a DOT understand the data and how they could be useful. One approach that shows potential is the visualization technique, which can help users connect data across an agency. More research is needed to show these data to the various internal divi- sions and how the data fit together to inform better decisions. â¢ Many DOTs are not satisfied that their WIM network can give them the data required to aid in freight and corridor planning. Research is needed to determine how additional databases and data mining and artificial intelligence (AI) analysis with existing data can be used in freight and corridor planning. â¢ Past research has investigated a pay-by-weight-distance replacement for gas taxes using WIM. More research is needed on this and other fee structures for the future.