BRIDGE INFRA- STRUCTURE Preservation - Transportation
BRIDGE INFRASTRUCTURE Preservation
T
he nation’s bridge infrastructure is deteriorating at an increasing rate. In 2007, roughly 12% (72,524) of U.S. bridges in the National Bridge Inventory were classified as “structurally deficient”. Due to the high cost of repair and replacement, most state transportation agencies are unable to cope with this trend. On a national level, the USDOT estimates that it would cost a total of $65.3 billion to correct all existing bridge deficiencies. Projected deficits in Highway Trust Fund revenues raise the question of how to fund potential increased spending on highway bridges. Structural deficiency does not necessarily imply an unsafe structure or imminent collapse but includes characteristics such as poor deck conditions and a lack of load ratings. Many heavily deteriorated bridges can still safely carry traffic. Uncertainties in site-specific traffic loading and bridge response challenge determination of those bridges most in need of repair and oftentimes lead to unnecessary or premature rehabilitations at a significant cost. During the 2006 Commercial Motor Vehicle Size and Weight Enforcement Scanning Study - sponsored by the Federal Highway Administration, the American Association of State Highway and Transportation Officials, and the National Cooperation Highway Research Program - a team of U.S transportation experts observed notable technology-based European enforcement policies and procedures leading to enhanced efficiency and effectiveness in bridge infrastructure preservation. A cornerstone technology supporting European bridge infrastructure preservation is bridge weigh-in-motion (WIM). Bridge WIM systems utilize strain transducers or gauges attached to the bridge soffit or embedded in the bridge deck and on-road axle detectors or Nothing-Onthe-Road/Free-of-Axle Detector (NORFAD) systems to provide information on axle and gross weights, axle spacing, speed, and position for commercial motor vehicles (CMVs) and other vehicles traveling at highway speeds. Bridge WIM systems also provide strain measurements and information to support accurate determination of influence lines, load distributions, and impact factors for additional bridge analysis. Because the measurements are performed while the entire vehicle is passing over the structure, the system is less influenced by dynamic effects than in-road WIM systems. Requested By: AASHTO Standing Committee on Highways Prepared By: Jodi L. Carson, P.E., Ph.D., Texas A&M Research Foundation on behalf of Texas Transportation Institute, Texas A&M University System, College Station, Texas Project Information: The information contained in this report was prepared as part of NCHRP Project 20-07, Task 254, Vehicle Size and Weight Management Technology Transfer and Best Practices. National Cooperative Highway Research Program, Transportation Research Board, http://www.trb.org/TRBNet/ProjectDisplay.asp?ProjectID=2335
OCTOBER 2008
This informational brief describes these policies and procedures and considers the potential for U.S. application, including the necessary supporting technologies and opportunities for incremental implementation. Anticipated benefits and associated cost savings related to operational enhancements, infrastructure preservation, increased safety, and reduced congestion and harmful emissions are also described.
Notable Policies and Procedures Unique European procedures related to bridge infrastructure preservation are focused on improved structural and safety assessments of existing bridges through measured rather than estimated loading and response data and opportunities for “soft” load testing using bridge WIM and other supporting technologies. In the U.S., a single test site is currently under development in Alabama, with the longer-term intent of deploying and evaluating bridge WIM systems in additional states through a pooled-fund effort or other mechanism.
Structural Assessment
Transportation officials in Slovenia have developed comprehensive, technology-based structural assessment procedures in an effort to optimize their Nation’s bridge rehabilitation and replacement. For existing bridges, important factors to consider include the condition and extent of damage to the structure, the loads to which an existing structure is subjected (i.e., dead and live), the resistance to loading that an existing structure provides (i.e., load carrying capacity), and the structure’s continued serviceability and potential obsolescence. The greatest uncertainties exist in determining the live loads (i.e., traffic) to which an existing structure is subjected and the structure’s response to those loads. In Slovenia, bridge WIM is used to reduce these uncertainties through the provision of improved traffic and structural data. When assessing load carrying capacity, a structure must adequately resist all live (i.e., traffic) and dead (i.e., bridge superstructure) loads applied to the structure, each multiplied by a safety factor to account for uncertainty in respective estimates. Higher uncertainty in estimates leads to higher safety factors and more stringent design and/or performance requirements for bridges. In Slovenia, bridge WIM systems are used to measure the actual traffic loading to which a structure is subjected, greatly increasing the certainty of live load estimates and subsequently allowing for a significant reduction in the live load safety factor. As such, conclusions regarding the safety of existing bridges in their current condition for their current loading may change, reducing rehabilitation costs and avoiding unnecessary replacement of serviceable highway structures. Traffic loading was observed to vary significantly at sites both within and outside of Slovenia as a result of variable economic activity and subsequent trade corridor development; regulations related to vehicle size and weight or time of day/day of week travel restrictions; and efficiency and effectiveness of local enforcement policies. Bridge WIM systems have proven to be a costeffective strategy in capturing these differences. By design, bridge WIM systems can be removed and installed at different sites in less than a day and with little or no disruption to traffic flow. Slovenian transportation officials are also using bridge WIM data to refine theoretical estimates of the impact or dynamic amplification factor (DAF) - the ratio between maximum dynamic and static loadings – to better estimate the true dynamic effects of live loads on a structure. Historically, DAFs have been conservatively assumed; applicable to many types of bridge structures irrespective of the structural dynamics and traffic characteristics of the site. The use of models to improve the accuracy of these factors is time-consuming and challenged by many unknowns. In Slovenia, bridge WIM systems are used to improve the estimation of DAFs using simulations based on measured vehicles speeds and axle loads and spacing. In initial investigations, the DAFs estimated using bridge WIM data for extreme load cases are considerably lower than those specified in the design codes, again suggesting a higher level of observed structure safety as compared to traditional method assessment results. Improving upon the theoretical assumptions about structural behavior, transportation officials in Slovenia use direct response measurements from bridge WIM systems to more accurately determine influence lines (IL) and the load distribution from normal traffic. In particular, the shift from theoretical to measured influence lines can dramatically change the input parameters used in the bridge structural assessment model. Bridge WIM systems also allow for the statistical estimation of load distributions between bridge members and across travel lanes, improving upon traditional “guestimation“ methods employed in Slovenia.
Measured IL
Calibrated measured IL Theoretical IL
Calibrated strain 3-axle truck Theoretical strain 3-axle truck
Safety Assessment
Similar to bridge structural assessment, bridge safety assessments consider the load carrying capacity of a structure with a focus on specific loading conditions rather than overall loading. Most often, safety assessments are used as part of the permit review process for oversize/overweight (OS/OW) movements to verify the safety of bridges along the permitted vehicle’s intended route. Because bridges may be required to support the full load of the CMV, their load carrying capacity often becomes the limiting factor in issuing a permit. Bridge safety assessments use the permit vehicle as the live load reference effectively eliminating any uncertainty related to loading. The noted improvements to theoretical assumptions supporting influence line, load distribution, and impact factor (DAFs) determination afforded through bridge WIM systems and described previously – combined with the added certainty in live load characteristics - enhance the accuracy of conclusions regarding the safety of an existing bridge under the intended vehicle loading. In France and Slovenia, calibrated influence lines derived from bridge WIM systems are routinely used to calculate the safety of a particular bridge under OS/OW loading using the vehicle’s exact axle loading and axle spacing. If the permitted vehicle loading approaches the load carrying capacity of the structure, additional constraints may be imposed that require the permitted vehicle’s driver to control speed, braking, and/or acceleration to limit dynamic impacts to the bridge.
Load Testing
As mentioned previously, traditional methods for calculating bridge load carrying capacity tend to be conservative to account for uncertainty levels in the live loads applied to a structure and the structure’s response to those loads. In many cases, these methods also neglect potential sources of reserve capacity (i.e., additional strength resulting from the slab/girder composite action in bridges designed as non-composite, rigid or semi-rigid connections designed as flexible, etc.) resulting in an underestimation of the structural soundness or safety of a structure. Load testing can be used to identify and quantify such sources of additional capacity present in the structure but not accounted for in theoretical models. Traditional load testing methods include proof load and diagnostic tests. Proof load tests use an external load that approaches the bridge’s design load to prove that the structure’s behavior is in compliance with the design. Proof load tests risk the potential for permanent damage or even failure of the bridge due to the high load applied. Diagnostic tests consider normal rather than extreme loading of a structure; pre-weighed vehicles are used to load the bridge statically. Both tests are generally costly to perform and require closing the bridge to traffic. As a less costly, less intrusive method, bridge WIM systems can support “soft” load testing using normal traffic loading and the observable structural behavior of the bridge. Soft load testing does not require the use of pre-weighed vehicles or bridge closure and does not risk overloading or damaging the structure. As such, soft load testing can be performed with little to no advance preparation or cost, particularly if the structure of interest is already instrumented with a bridge WIM system.
Supporting Technologies
Bridge WIM System • Weight (Voltage)/ Axle Sensors • Computer Interface/ PC Software
Functions • Measures and records vehicle weight using existing roadway structures instrumented with strain transducers or gauges. Bridge deflections are converted to weight measurements. • Measures and records axles using traditional in-road sensors or through Nothing-on-theRoad/Free-of-Axle Detector (NORFAD) systems. Considerations • NORFAD systems offer improved durability and easier installation with no traffic delays. • Requires suitable bridge in a location where WIM data is warranted. • Proven most successful on short, stiff bridge structures. • Structural assessments using strain data may require transducer calibration. • Calibration may require a high expertise level. Estimated Costs • $100,000 - $130,000 per bridge/system. • Varies based on weight sensor type, on-site communication requirements.
Archived Records Database
Functions • Supports data-driven scheduling of enforcement resources. • Supports data-driven preventative carrier contacts. • Supports continuous calibration and enhanced data quality. • Encourages long-term performance monitoring. Considerations • Requires procedures for quality control. Estimated Costs • $225,000 - $300,000
Perceived and Reported Benefits
Incremental Implementation Steps Archived Records Database
STRUCTURAL ASSESSMENTS
SAFETY ASSESSMENTS
LOAD TESTING
Database
Database
Database
Operational benefits attributable to the observed technology-based bridge Voltage/Axle Sensors Voltage/Axle Sensors Voltage/Axle Sensors infrastructure preservation policies and Bridge WIM System procedures are largely anecdotal. Computer Interface/ Computer Interface/ Computer Interface/ Using bridge WIM and other supporting Software Software Software technologies, French and Slovenian transportation officials report improved structural and safety assessments of existing bridges through measured rather than estimated loading and response data. Bridge WIM systems provide greater certainty in the nature and dynamic effects of traffic loads on a structure, as well as providing a cost-effective and non-intrusive means to capture data for multiple structures to account for site-specific loading variability. In addition, bridge WIM systems provide a more accurate determination of influence lines, load distribution, and impact factors that reflect the structural behaviour of the bridge. Bridge WIM systems also provide opportunities for “soft” load testing that can be performed at significantly less cost than traditional proof load and diagnostic testing, does not require closing the bridge to traffic, and poses no risk for damage to the structure. These operational benefits are supplemental to the traditional capabilities related to enforcement and data collection realized through the use of in-road WIM systems. Broader benefits related to infrastructure preservation, increased safety, and reduced congestion and harmful emissions are also not well-documented but could prove significant in the U.S. Motivating the development of their comprehensive, technology-based structural assessment procedures, transportation officials in Slovenia are similarly challenged with a deteriorating infrastructure and constrained spending for bridge rehabilitation and replacement. More accurate structural and safety assessments that are able to demonstrate the adequacy of existing bridges in their current condition under current loading could result in less severe or delayed rehabilitation measures, fewer associated traffic delays, and significant cost savings without compromise to safety. Improved, technology-based structural assessment procedures, if applied in the U.S., could dramatically reduce, refine, and prioritize bridge rehabilitation and replacement actions and concurrently reduce associated costs, currently estimated at $65.3 billion nationwide.
Interface with Other Functional Areas WIM SYSTEM OS/OW BRIDGE CALIBRATION PERMITTING PRESERVATION
In fra
SUPPORTING TECHNOLOGIES
ENFORCEMENT WEIGHT
str uc Pr tu ere se Pr l e es Di cti re er o n ct va tio Pr Enfo n erc se e m l e Re ect ion nt so ur ce Pr Sc ev en he ta du Di t i lin v re e g ct C E a rri n By er pa forc Co em ss nt Pr en Co ac e t nt ts inu ven tio ou Qu sC n ali ty ali A br Dy at na ssur an ion m ic c Se e lf P Cal ibr er a m Br tio itti idg ng n e Re Saf /Ro u et m y A ting ot e s St Fi ru eld sess ctu m Ve en r al Sa t As rific fe a ty se tio A s n Lo sm ss ad e en t Te ssm en sti t ng
SIZE
Overheight Vehicle Detection System
Vehicle Profiler System In-road WIM System Bridge WIM System Dynamic Calibration Vehicle Vehicle Identification System
Advanced Routing/Permitting System Archived Records Database
Disclaimer: The opinions and conclusions expressed or implied are those of the research agency that performed the research and not necessarily those of the Transportation Research Board or its sponsors. The information contained in this document was taken directly from the submission of the author(s). This document is not a report of the Transportation Research Board or of the National Research Council.
T
he nation’s bridge infrastructure is deteriorating at an increasing rate. In 2007, roughly 12% (72,524) of U.S. bridges in the National Bridge Inventory were classified as “structurally deficient”. Due to the high cost of repair and replacement, most state transportation agencies are unable to cope with this trend. On a national level, the USDOT estimates that it would cost a total of $65.3 billion to correct all existing bridge deficiencies. Projected deficits in Highway Trust Fund revenues raise the question of how to fund potential increased spending on highway bridges. Structural deficiency does not necessarily imply an unsafe structure or imminent collapse but includes characteristics such as poor deck conditions and a lack of load ratings. Many heavily deteriorated bridges can still safely carry traffic. Uncertainties in site-specific traffic loading and bridge response challenge determination of those bridges most in need of repair and oftentimes lead to unnecessary or premature rehabilitations at a significant cost. During the 2006 Commercial Motor Vehicle Size and Weight Enforcement Scanning Study - sponsored by the Federal Highway Administration, the American Association of State Highway and Transportation Officials, and the National Cooperation Highway Research Program - a team of U.S transportation experts observed notable technology-based European enforcement policies and procedures leading to enhanced efficiency and effectiveness in bridge infrastructure preservation. A cornerstone technology supporting European bridge infrastructure preservation is bridge weigh-in-motion (WIM). Bridge WIM systems utilize strain transducers or gauges attached to the bridge soffit or embedded in the bridge deck and on-road axle detectors or Nothing-Onthe-Road/Free-of-Axle Detector (NORFAD) systems to provide information on axle and gross weights, axle spacing, speed, and position for commercial motor vehicles (CMVs) and other vehicles traveling at highway speeds. Bridge WIM systems also provide strain measurements and information to support accurate determination of influence lines, load distributions, and impact factors for additional bridge analysis. Because the measurements are performed while the entire vehicle is passing over the structure, the system is less influenced by dynamic effects than in-road WIM systems. Requested By: AASHTO Standing Committee on Highways Prepared By: Jodi L. Carson, P.E., Ph.D., Texas A&M Research Foundation on behalf of Texas Transportation Institute, Texas A&M University System, College Station, Texas Project Information: The information contained in this report was prepared as part of NCHRP Project 20-07, Task 254, Vehicle Size and Weight Management Technology Transfer and Best Practices. National Cooperative Highway Research Program, Transportation Research Board, http://www.trb.org/TRBNet/ProjectDisplay.asp?ProjectID=2335
OCTOBER 2008
This informational brief describes these policies and procedures and considers the potential for U.S. application, including the necessary supporting technologies and opportunities for incremental implementation. Anticipated benefits and associated cost savings related to operational enhancements, infrastructure preservation, increased safety, and reduced congestion and harmful emissions are also described.
Notable Policies and Procedures Unique European procedures related to bridge infrastructure preservation are focused on improved structural and safety assessments of existing bridges through measured rather than estimated loading and response data and opportunities for “soft” load testing using bridge WIM and other supporting technologies. In the U.S., a single test site is currently under development in Alabama, with the longer-term intent of deploying and evaluating bridge WIM systems in additional states through a pooled-fund effort or other mechanism.
Structural Assessment
Transportation officials in Slovenia have developed comprehensive, technology-based structural assessment procedures in an effort to optimize their Nation’s bridge rehabilitation and replacement. For existing bridges, important factors to consider include the condition and extent of damage to the structure, the loads to which an existing structure is subjected (i.e., dead and live), the resistance to loading that an existing structure provides (i.e., load carrying capacity), and the structure’s continued serviceability and potential obsolescence. The greatest uncertainties exist in determining the live loads (i.e., traffic) to which an existing structure is subjected and the structure’s response to those loads. In Slovenia, bridge WIM is used to reduce these uncertainties through the provision of improved traffic and structural data. When assessing load carrying capacity, a structure must adequately resist all live (i.e., traffic) and dead (i.e., bridge superstructure) loads applied to the structure, each multiplied by a safety factor to account for uncertainty in respective estimates. Higher uncertainty in estimates leads to higher safety factors and more stringent design and/or performance requirements for bridges. In Slovenia, bridge WIM systems are used to measure the actual traffic loading to which a structure is subjected, greatly increasing the certainty of live load estimates and subsequently allowing for a significant reduction in the live load safety factor. As such, conclusions regarding the safety of existing bridges in their current condition for their current loading may change, reducing rehabilitation costs and avoiding unnecessary replacement of serviceable highway structures. Traffic loading was observed to vary significantly at sites both within and outside of Slovenia as a result of variable economic activity and subsequent trade corridor development; regulations related to vehicle size and weight or time of day/day of week travel restrictions; and efficiency and effectiveness of local enforcement policies. Bridge WIM systems have proven to be a costeffective strategy in capturing these differences. By design, bridge WIM systems can be removed and installed at different sites in less than a day and with little or no disruption to traffic flow. Slovenian transportation officials are also using bridge WIM data to refine theoretical estimates of the impact or dynamic amplification factor (DAF) - the ratio between maximum dynamic and static loadings – to better estimate the true dynamic effects of live loads on a structure. Historically, DAFs have been conservatively assumed; applicable to many types of bridge structures irrespective of the structural dynamics and traffic characteristics of the site. The use of models to improve the accuracy of these factors is time-consuming and challenged by many unknowns. In Slovenia, bridge WIM systems are used to improve the estimation of DAFs using simulations based on measured vehicles speeds and axle loads and spacing. In initial investigations, the DAFs estimated using bridge WIM data for extreme load cases are considerably lower than those specified in the design codes, again suggesting a higher level of observed structure safety as compared to traditional method assessment results. Improving upon the theoretical assumptions about structural behavior, transportation officials in Slovenia use direct response measurements from bridge WIM systems to more accurately determine influence lines (IL) and the load distribution from normal traffic. In particular, the shift from theoretical to measured influence lines can dramatically change the input parameters used in the bridge structural assessment model. Bridge WIM systems also allow for the statistical estimation of load distributions between bridge members and across travel lanes, improving upon traditional “guestimation“ methods employed in Slovenia.
Measured IL
Calibrated measured IL Theoretical IL
Calibrated strain 3-axle truck Theoretical strain 3-axle truck
Safety Assessment
Similar to bridge structural assessment, bridge safety assessments consider the load carrying capacity of a structure with a focus on specific loading conditions rather than overall loading. Most often, safety assessments are used as part of the permit review process for oversize/overweight (OS/OW) movements to verify the safety of bridges along the permitted vehicle’s intended route. Because bridges may be required to support the full load of the CMV, their load carrying capacity often becomes the limiting factor in issuing a permit. Bridge safety assessments use the permit vehicle as the live load reference effectively eliminating any uncertainty related to loading. The noted improvements to theoretical assumptions supporting influence line, load distribution, and impact factor (DAFs) determination afforded through bridge WIM systems and described previously – combined with the added certainty in live load characteristics - enhance the accuracy of conclusions regarding the safety of an existing bridge under the intended vehicle loading. In France and Slovenia, calibrated influence lines derived from bridge WIM systems are routinely used to calculate the safety of a particular bridge under OS/OW loading using the vehicle’s exact axle loading and axle spacing. If the permitted vehicle loading approaches the load carrying capacity of the structure, additional constraints may be imposed that require the permitted vehicle’s driver to control speed, braking, and/or acceleration to limit dynamic impacts to the bridge.
Load Testing
As mentioned previously, traditional methods for calculating bridge load carrying capacity tend to be conservative to account for uncertainty levels in the live loads applied to a structure and the structure’s response to those loads. In many cases, these methods also neglect potential sources of reserve capacity (i.e., additional strength resulting from the slab/girder composite action in bridges designed as non-composite, rigid or semi-rigid connections designed as flexible, etc.) resulting in an underestimation of the structural soundness or safety of a structure. Load testing can be used to identify and quantify such sources of additional capacity present in the structure but not accounted for in theoretical models. Traditional load testing methods include proof load and diagnostic tests. Proof load tests use an external load that approaches the bridge’s design load to prove that the structure’s behavior is in compliance with the design. Proof load tests risk the potential for permanent damage or even failure of the bridge due to the high load applied. Diagnostic tests consider normal rather than extreme loading of a structure; pre-weighed vehicles are used to load the bridge statically. Both tests are generally costly to perform and require closing the bridge to traffic. As a less costly, less intrusive method, bridge WIM systems can support “soft” load testing using normal traffic loading and the observable structural behavior of the bridge. Soft load testing does not require the use of pre-weighed vehicles or bridge closure and does not risk overloading or damaging the structure. As such, soft load testing can be performed with little to no advance preparation or cost, particularly if the structure of interest is already instrumented with a bridge WIM system.
Supporting Technologies
Bridge WIM System • Weight (Voltage)/ Axle Sensors • Computer Interface/ PC Software
Functions • Measures and records vehicle weight using existing roadway structures instrumented with strain transducers or gauges. Bridge deflections are converted to weight measurements. • Measures and records axles using traditional in-road sensors or through Nothing-on-theRoad/Free-of-Axle Detector (NORFAD) systems. Considerations • NORFAD systems offer improved durability and easier installation with no traffic delays. • Requires suitable bridge in a location where WIM data is warranted. • Proven most successful on short, stiff bridge structures. • Structural assessments using strain data may require transducer calibration. • Calibration may require a high expertise level. Estimated Costs • $100,000 - $130,000 per bridge/system. • Varies based on weight sensor type, on-site communication requirements.
Archived Records Database
Functions • Supports data-driven scheduling of enforcement resources. • Supports data-driven preventative carrier contacts. • Supports continuous calibration and enhanced data quality. • Encourages long-term performance monitoring. Considerations • Requires procedures for quality control. Estimated Costs • $225,000 - $300,000
Perceived and Reported Benefits
Incremental Implementation Steps Archived Records Database
STRUCTURAL ASSESSMENTS
SAFETY ASSESSMENTS
LOAD TESTING
Database
Database
Database
Operational benefits attributable to the observed technology-based bridge Voltage/Axle Sensors Voltage/Axle Sensors Voltage/Axle Sensors infrastructure preservation policies and Bridge WIM System procedures are largely anecdotal. Computer Interface/ Computer Interface/ Computer Interface/ Using bridge WIM and other supporting Software Software Software technologies, French and Slovenian transportation officials report improved structural and safety assessments of existing bridges through measured rather than estimated loading and response data. Bridge WIM systems provide greater certainty in the nature and dynamic effects of traffic loads on a structure, as well as providing a cost-effective and non-intrusive means to capture data for multiple structures to account for site-specific loading variability. In addition, bridge WIM systems provide a more accurate determination of influence lines, load distribution, and impact factors that reflect the structural behaviour of the bridge. Bridge WIM systems also provide opportunities for “soft” load testing that can be performed at significantly less cost than traditional proof load and diagnostic testing, does not require closing the bridge to traffic, and poses no risk for damage to the structure. These operational benefits are supplemental to the traditional capabilities related to enforcement and data collection realized through the use of in-road WIM systems. Broader benefits related to infrastructure preservation, increased safety, and reduced congestion and harmful emissions are also not well-documented but could prove significant in the U.S. Motivating the development of their comprehensive, technology-based structural assessment procedures, transportation officials in Slovenia are similarly challenged with a deteriorating infrastructure and constrained spending for bridge rehabilitation and replacement. More accurate structural and safety assessments that are able to demonstrate the adequacy of existing bridges in their current condition under current loading could result in less severe or delayed rehabilitation measures, fewer associated traffic delays, and significant cost savings without compromise to safety. Improved, technology-based structural assessment procedures, if applied in the U.S., could dramatically reduce, refine, and prioritize bridge rehabilitation and replacement actions and concurrently reduce associated costs, currently estimated at $65.3 billion nationwide.
Interface with Other Functional Areas WIM SYSTEM OS/OW BRIDGE CALIBRATION PERMITTING PRESERVATION
In fra
SUPPORTING TECHNOLOGIES
ENFORCEMENT WEIGHT
str uc Pr tu ere se Pr l e es Di cti re er o n ct va tio Pr Enfo n erc se e m l e Re ect ion nt so ur ce Pr Sc ev en he ta du Di t i lin v re e g ct C E a rri n By er pa forc Co em ss nt Pr en Co ac e t nt ts inu ven tio ou Qu sC n ali ty ali A br Dy at na ssur an ion m ic c Se e lf P Cal ibr er a m Br tio itti idg ng n e Re Saf /Ro u et m y A ting ot e s St Fi ru eld sess ctu m Ve en r al Sa t As rific fe a ty se tio A s n Lo sm ss ad e en t Te ssm en sti t ng
SIZE
Overheight Vehicle Detection System
Vehicle Profiler System In-road WIM System Bridge WIM System Dynamic Calibration Vehicle Vehicle Identification System
Advanced Routing/Permitting System Archived Records Database
Disclaimer: The opinions and conclusions expressed or implied are those of the research agency that performed the research and not necessarily those of the Transportation Research Board or its sponsors. The information contained in this document was taken directly from the submission of the author(s). This document is not a report of the Transportation Research Board or of the National Research Council.
