bluuebunny/crossref_metadata_2025 huggingface dataset:
Truck-Induced Dynamic Wind Loads on Variable-Message Signs
Authors: Cook Ronald A. , Bloomquist David , Agosta Angelica M.
Published: April 2007

Large trucks, particularly those with over-cab air deflectors, produce dynamic wind pressures on overhead structures. Oscillations of overhead variable-message sign structures have been observed as a result of these truck-induced wind pressures. The purpose of this research was to determine the magnitude, direction, and frequency of these pressure distributions. The choice of instrumentation used, the design of the apparatus, and the data obtained are discussed. A multiprobe device consisting of Pitot tubes and variable-reluctance pressure transducers was combined with a data acquisition system. Field readings were taken by mounting the apparatus on a bridge overpass and collecting data as trucks passed beneath the bridge. It was found that the wind pressures produced by the trucks were not as large as anticipated, but the frequency of the wind was close to the natural frequency of a typical variable-message sign structure. This creates a resonance condition believed to be a major cause of the oscillations. One possible solution is to increase the stiffness of the structure.
Structural and Hydraulic Performance of 1500-mm Smooth-Interior High-Density Polyethylene Pipe in Soil Cell
Authors: Daley Victoria
Published: April 2007

Soil cell tests have been used for decades to evaluate the structural performance of a variety of pipes. The structural performance of a 1500-mm (60-in.)-diameter, corrugated-exterior, smooth-interior high-density polyethylene pipe in a soil cell with two different backfill strengths is presented, and the results are compared with the values predicted theoretically. Specifiers demand assurance of the long-term hydraulic performance of smooth-interior corrugated polyethylene pipe. Fortunately, a mathematical model that allows for the estimation of the Manning value by using measurable pipe dimensions and flow characteristics is available. A discussion of the geometric changes in the interior pipe surface measured during the soil cell test is included, and an estimate of the resulting Manning values is provided. The results indicated a maximum increase in Manning values of approximately 3 or 10 percent, depending on backfill, for pipe buried within current industry recommendations for cover height.
Laboratory and Field Testing of Large-Diameter Plastic Pipe
Authors: Fleming P. R. , Faragher E. , Rogers C. D. F.
Published: April 2007

Flexible plastic pipe is increasingly being used in the United Kingdom for drainage and ducting (conduit) purposes. This increase in use is leading to the introduction of larger-diameter pipes. The U.K. Department of Transport (DoT) uses a recently developed, theoretical method to specify installation conditions in place of traditional techniques (e.g., Spangler’s Iowa method). The DoT design method is outlined. The extensive program of laboratory and field testing carried out at Lough-borough University to determine the performance of plastic pipes under a range of loading conditions that may be expected in practice is then described. Laboratory test results compared well with the results obtained in the field once the different boundary conditions were accounted for, thereby validating the laboratory test methods by suggesting how allowance for field conditions can be made. Some reference is made to the shapes of deformation (determined from circumferential strain data) and the effect of installation conditions upon them. Pipe deformations were found to be well within acceptable, conservative limits under all load regimens, and near equilibrium of the pipe-soil system was established relatively quickly following application of a static or a dynamic load sequence to it.
Field Performance of Instrumented Concrete Pipe Under Deep Burial
Authors: Hazen Glenn A. , Sargand Shad M. , Haque Mohammed , Hurd John O.
Published: April 2007

Two 1.524-m-diameter, reinforced concrete pipes were instrumented to compare field results with design calculations. A computer program, Standard Installation Direct Design, developed by the American Concrete Pipe Association was used to design the pipe. Instrumented pipes were completely monitored until 11.9 m of cover had been placed. Measurements of soil contact pressures and vertical and horizontal deflections continued for 6 months. The computer-simulated and observed responses of the buried concrete pipe installations were compared. Pipe contact pressures measured at the invert were much smaller than those assumed from calculations of thrust and moment. Design moments were conservative compared with the experimentally measured values. Thrusts are difficult to calculate accurately and show large experimental variations.
Evaluation of Roadside Inspection Selection System for Commercial Vehicles
Authors: Lantz Brenda M. , Blevins Michael W. , Hillegass Thomas J.
Published: April 2007

The development and testing of the roadside Inspection Selection System (ISS) have been in progress for more than 2 years. The ISS was developed as part of the Aspen roadside inspection software system in response to a 1995 congressional mandate calling for use of prior carrier safety data to guide in selection of commercial vehicles and drivers to undergo roadside inspections. The Aspen system includes software that helps conduct roadside inspections with portable microcomputers. Ten states were involved in the initial testing of the ISS, but a majority of states throughout the United States are now using the system. An analysis of almost 40,000 inspections conducted in 1996 revealed that the vehicle out-of-service (OOS) rate was 33.7 percent for those vehicles the ISS recommended for inspection versus 20.0 percent for those it did not. The driver OOS rate was 13.5 percent for those drivers recommended for inspection versus 9.9 percent for those not recommended. The ISS will thus help in targeting relatively unsafe carriers (as well as those for which there are insufficient data) and reduce the inspection burden on carriers proved to be safe. This means that more efficient use will be made of scarce resources by focusing on less safe vehicles and drivers. In addition, use of the ISS offers substantial benefits to society in safety and to safe motor carriers in cost savings. Presentations of the system and results of an evaluation survey completed by inspectors show the ISS to be well accepted by both inspectors and the motor carrier community.
New Fabry-Perot Fiber-Optic Sensors for Structural and Geotechnical Monitoring Applications
Authors: Choquet P. , Leroux R. , Juneau F.
Published: April 2007

A new line of fiber-optic sensors suited for structural and geotechnical monitoring purposes is presented. A Fabry-Perot strain gauge is contained in each of the new sensors introduced here: four embedded and surface-type strain gauges and one type of temperature gauge. Described here are the working and reading principles of the basic Fabry-Perot strain gauge. One of the gauge’s features that allows for temperature-compensated or noncompensated measurements is described, and the various sensors constructed around the gauge are presented. These newly developed sensors exhibit high accuracy and repeatability, as illustrated by various calibration tests reported here.
Three-Dimensional Structural Strain Measurement with the Use of Fiber-Optic Sensors
Authors: Grossman Barry G. , Huang Li-Tien , Cosentino Paul J. , von Eckroth Wulf
Published: April 2007

Three-dimensional strain sensing inside a structure is not feasible with conventional strain sensing techniques such as electrical strain gauges, which are limited to surface measurements. Three-dimensional strain measurement inside a structure would find uses in a variety of new applications: enhanced understanding and detection of composite failure modes, such as delamination; sensing for adaptive structural control; intelligent vehicle highway systems; and structural health monitoring systems for civil structures. The latter application could involve remotely monitoring structural integrity during and after an earthquake, for example. A fiber-optic strain sensor array (FOSSA) in a planar, patch-like configuration was developed, and accurate measurement of the three principal strains inside a simple structure was demonstrated. The planar configuration was chosen to avoid the difficulty and structural degradation of embedding optical sensors in three planes. Two extrinsic Fabry-Perot interferometric (EFPI) sensors and one polari-metric sensor form the planar sensor array. The two EFPI sensors were placed perpendicular to each other in the sensor plane to extract the two normal strain components along the x and y axes. The polarimetric sensor embedded in the plane was used to extract the third normal strain acting on the z axis. The sensor array was embedded in an epoxy resin cube and loaded to 454 kg (1,000 1b) with a loading machine. The strains that were measured correlated well with the external strains measured with surface-bonded electrical strain gauges. The variation in measured strain between the two sensor systems was less than 4 percent for all three principal axes.
Subsurface Drainage Systems in Roadway Construction
Authors: Daleiden Jerome F. , Peirce Laurence L.
Published: April 2007

The installation of subsurface drainage systems has been a common practice in roadway construction for many years. Until recently, however, the ability to inspect and report on the condition of these systems once they are in place has been limited. The use of a high-tech, closed-circuit video monitoring system for the inspection of subsurface drainage systems has been developed and utilized with a high degree of success. The use of this system is beneficial for maintenance and rehabilitation of existing systems and as a quality control measure for new highway systems. In an ongoing project for FHWA, video monitoring has identified crushed mainline drainage pipes in new systems that have yet to be open to traffic. All of the components of this monitoring system can be easily operated by one person in the field. Substantial cost savings can be realized by accurately identifying the specific areas that need repair rather than assuming that an entire system needs to be replaced in highway rehabilitation projects. Results from use of this new technology to date are presented here.
Proposed Evaluation of Base Materials for Drainability
Authors: Tandon Vivek , Picornell Miguel
Published: April 2007

Base materials are normally selected to achieve maximum density and possess sufficient stiffness and strength to carry traffic loads. Long-time concerns about the poor drainability of these materials have recently prompted the highway materials community to address this problem. The main objectives of the research reported here were to evaluate the drainability of base materials used in Texas and to propose and evaluate modified materials that could improve drainability while maintaining stiffness and strength levels. Drainability is evaluated on the basis of the permeability coefficient and water retention tests. The water retention test was found to be a much easier test to perform than the permeability test and is believed to be much more directly related to the drainability of the compacted base than the permeability coefficient. Alternative materials evaluated consisted of open-graded bases and cement-stabilized gravel. The results of the present study indicate that cement-stabilized gravel is the best alternative to achieve high stiffness and strength and at the same time minimize water retention capacity.
Framework for Selecting Effective Preventive Maintenance Treatments for Flexible Pavements
Authors: Hicks R. Gary , Dunn Kimberly , Moulthrop James S.
Published: April 2007

Preventive maintenance techniques are considered useful in extending the life of a pavement if applied at the right time. Discussed here is a framework for a process that can be used to select the proper maintenance strategies for different distress types in asphalt pavements, depending on traffic level and environment. Maintenance treatments addressed include only crack seals, fog seals, slurry seals, microsurfacings, chip seals, thin asphalt concrete overlays, and other thin surface treatments. Types of distress considered include roughness, rutting, fatigue cracking, longitudinal cracking, raveling, weathering, and bleeding. Decision trees, based on the authors' experiences, are presented to illustrate the process in selecting appropriate maintenance treatments. A framework for evaluating the cost-effectiveness of the various maintenance treatments is presented. Existing methods for evaluating cost-effectiveness of maintenance are discussed together with their strengths and weaknesses. An example of cost-effectiveness for different maintenance treatments is also briefly presented.
The Great Unsealing: A Perspective on Portland Cement Concrete Joint Sealing
Authors: Shober Stephen F.
Published: April 2007

The general mission of most transportation agencies is to ensure a customer focus in the development and operation of a safe and efficient transportation system. The customers desire comfort, convenience, safety, and cost-effectiveness in a transportation system. Agency research must have the objectives of addressing customer-related issues and measuring benefits of importance to them. Accordingly, any joint and sealant research must answer the questions, Why do we seal? and Is it cost-effective? Joint and sealant studies of portland cement concrete (PCC) pavements must address whether joint sealing enhances total pavement performance and is cost-effective, and, if so, what sealant system should be used. The Wisconsin Department of Transportation (WisDOT) has been studying the effect of PCC joint/crack sealing on total pavement performance for 50 years. By 1967 there was substantial documentation that filling and refilling of contraction joints had no beneficial effect on pavement performance. By 1984, it was concluded that pavements with unsealed joints had better overall performance (distress, ride, materials integrity) than pavements with sealed joints. In 1990, WisDOT passed a policy eliminating all PCC joint sealing, in new construction and maintenance. This "no-seal" policy has saved Wisconsin $6,000,000 annually with no loss in pavement performance and with increased customer safety and convenience. The entire PCC sealing issue is beginning to be addressed at the national level, ensuring no false assumptions and with the customer’s needs in view.
Comparison of Methodologies to Predict Bridge Deterioration
Authors: Bulusu Srinivas , Sinha Kumares C.
Published: April 2007

Two methods for the estimation of bridge condition states were examined, one based on the Bayesian approach and the other using a binary probit model. The Bayesian approach was considered so that experts' opinions could be combined with observed data. Prior transition probabilities, based on bridge inspectors' experiences, were assumed to follow Dirichlet distribution. Observed data followed a multinomial distribution. The updated transition probabilities were used to predict bridge condition states. In the second approach, deterioration models were developed for each condition state. The dependent variable is a zero/one indicator variable for condition switching state. The binary probit models developed considered the discreteness of condition states and they explicitly linked deterioration to relevant explanatory variables. This approach also incorporated heterogeneity and state dependence due to the use of panel data. An application of these methodologies was demonstrated for substructure element using the Indiana bridge data base.
Underwater Bridge Deterioration and the Impact of Bridge Inspection in Mississippi
Authors: Avent R. Richard , Alawady Mohamed , Guthrie Larry
Published: April 2007

During 1988 and 1989 the state of Mississippi conducted the first statewide underwater inspection program following the issue of FHWA guidelines for regular underwater bridge inspections. During 1994 and 1995, a second state-wide underwater bridge inspection program was conducted. The results of these two inspections are compared and the impact of the underwater inspection program is assessed.
Development of Conductive Polyester Concrete for Bridge-Deck Cathodic Protection and Ice Control
Authors: Maggenti Ric G. , Carter Richard R. , Meline Robert
Published: April 2007

An electrically conductive polymer concrete was developed and field tested by the California Department of Transportation. The conductive polymer concrete was a blend of polyester resin, mineral aggregate, and carbon in the form of coke breeze. After laboratory work it was used as an anode for cathodic protection (CP) of reinforcing steel on two bridge decks and used as a heater on another. The first CP system was placed on an entire bridge deck in 1988. Field data generated from 1988 to 1996 indicated it was quite successful, although there were some shortcomings. Following improvements a second bridge deck CP system is being placed. Use of the polymer as a heater was tried in 1990 by placing a 3 m2 (10 ft2) test section on a deck located on I-80 in the Sierra Nevada mountains. The heater was evaluated during the winter of 1990–1991. The results of the evaluation indicated such a heater is feasible.
Effect of Electrochemical Chloride Extraction on Concrete Properties: Investigation of Field Concrete
Authors: Broomfield J. P. , Buenfeld N. R.
Published: April 2007

An investigation to determine the suitability of electrochemical chloride extraction (ECE, also known as desalination) for the reinforced concrete substructure on a bridge in the north of England is reported. Part of a cross head was removed during demolition. After ECE treatment by the proprietary Norcure technique, cores were taken from the treated area. Representative cores were then taken from adjacent cross heads and subjected to a series of laboratory tests and examinations. These tests revealed that the treatment increased the concrete’s ability to resist the ingress of water, oxygen, and ions. This should make the concrete more durable and more resistant to future chloride ingress and corrosion.
Field Investigation of Corrosion-Protection Performance of Bridge Decks Constructed with Epoxy-Coated Reinforcing Steel in Virginia
Authors: Weyers Richard E. , Pyc Wioleta , Zemajtis Jerzy , Liu Youping , Mokarem David , Sprinkel Michael M.
Published: April 2007

The corrosion-protection performance of epoxy-coated reinforcing steel (ECR) in three 17-year-old bridge decks in Virginia was assessed. The decks had an upper mat of ECR and a lower mat of bare steel. Surface cracking in the right traffic lane was visually surveyed and 12 cores randomly located in the lowest 12th percentile cover depth in each deck were drilled. The concrete core and the extract ECR were visually inspected. In the concrete moisture content, absorption, percent saturation, carbonation depth, and the effective chloride diffusion constant were measured. In the ECR physical damage, coating thickness, adhesion loss and corrosion at damaged sites, and undercoating corrosion at adhesion test sites were measured. The chloride content of the concrete and carbonation of the ECR trace were determined. Significant coating adhesion loss occurred before the chloride arrived at the bar depth. The debonding of the epoxy is wet debonding, which is predicted by the negative thermodynamic work of adhesion. ECR will extend the service life of only 5 percent of the bridge decks in Virginia. Thus, its use is not cost-effective. Additional decks should be evaluated to confirm the results of this and other studies.
Stated Choice for Transportation Demand Management Models: Using a Disaggregate Truth Set To Study Predictive Validity
Authors: Beaton Patrick , Chen Cynthia , Meghdir Hamo
Published: April 2007

Discrete choice models have expanded the ability of transportation planners to forecast future trends. Where new services or policies are proposed, the stated-choice approach can provide an objective basis for forecasts. Stated-choice models are subject to a range of experimental error not found in revealed-preference designs. Primary among the concerns facing researchers is the ability of respondents to understand and operate on hypothetical choice scenarios in a manner that will reproduce choices made under actual situations. These concerns are specified in the scaling factor. Estimation of the scaling factor has proceeded through various ways to link actual decisions to comparable decisions made under hypothetical conditions. However, where the alternative is new, real decision data are not available. The level of error incorporated in a study where no real-world information on the scaling factor is available is examined. The test of predictive validity focuses attention on the switching behavior of commuters at a single employment site. The results indicate that switching behavior between single-occupant vehicle and high-occupancy vehicle modes is forecast within 1 percent by stated-choice techniques and within 10 percent by backcasting techniques with revealed-preference data.
Travel, Emissions, and Welfare Effects of Travel Demand Management Measures
Authors: Rodier Caroline J. , Johnston Robert A.
Published: April 2007

Land-use intensification measures and pricing policies are compared and combined with high-occupancy vehicle (HOV) lane and light-rail transit expansion scenarios in the Sacramento, California, region and evaluated against travel, emissions, consumer welfare, and equity criteria. A state-of-the-practice regional travel demand model is used to simulate the travel effects of these scenarios. The Small and Rosen method of obtaining consumer welfare is applied to the mode-choice models in the travel model. The most politically feasible scenarios were found to provide at best only modest improvements in congestion and emissions. Welfare losses were obtained for the HOV lane scenario, suggesting that care must be taken in project planning to ensure that savings in travel time are large enough to offset the unobserved cost of increased travel by car. Transit investment and supportive land-use intensification provided larger reductions in congestion and emissions and increased consumer welfare for all income classes. As a group, the scenarios that included pricing policies provided the greatest reduction in travel delay and emissions, increased total consumer welfare, and imposed losses on the lowest income group. However, it may be possible to combine pricing policies with more significantly expanded transit and roadway capacity and compensatory payments to increase consumer welfare for all income classes.
Transit and Carpool Commuting and Household Vehicle Trip Making: Panel Data Analysis
Authors: Bard Erin A.
Published: April 2007

Most of the evaluation of commute trip reduction programs centers on the effect on reducing driveway trips at the work site. Little has been done to explore the effects of such programs on overall trip making. This work is meant to help understand this relationship by determining the association between transit and carpool commuting and overall household vehicle trip making. Household activity models have indicated that an individual's travel decisions influence (and are influenced by) the decisions of other household members. It is thus postulated that one household member's choice of transit or carpool for the morning trip to work will affect the mode choices of the other household members. In addition, the choice of mode to work will affect the individual's mode choices for trips other than the morning trip to work. The analysis uses the first four waves of the Puget Sound Transportation Panel survey to construct linear econometric longitudinal trip generation models (random effects models). The results of the modeling indicate that one household member's mode choice to work does affect overall household vehicle travel. Compared with driving alone to work, if one household member chooses transit to work, overall household vehicle trips are reduced (on average). Carpooling by one household member is associated with little change in overall household travel, with average daily household vehicle trips ranging between one trip fewer and one trip greater than households where each driver in the household drives to work in a separate, single-occupant vehicle. The analysis strengthens the associations to imply causal links. The model results suggest that an improved understanding of interactions among household members is necessary to define strategies in support of commute trip reduction policies to better meet air quality and congestion-management goals.
Benefit/Cost Analysis of Central Ohio Commuter-Assistance Program
Authors: Al-Akhras Ahmad , Kalra Traci , Gill Nick
Published: April 2007

The question of the effectiveness of ridesharing programs is addressed. The Commuter Assistance Program of the Mid-Ohio Regional Planning Commission was analyzed. The methodology of performing the analysis by the benefit/cost approach is described. Benefits are estimated based on the vehicle kilometers and vehicle trips reduced as a result of ridesharing arrangements formed through the program. Benefits are those that affect users of the service in terms of direct monetary savings and indirect savings in terms of reducing mobile emissions. Results of the analysis indicate that ridesharing is a low-cost approach to solving transportation congestion with a relatively high return on investment.
Washington State's Commute Trip Reduction Program: Phase 1: Assessment and Implications for Program Design
Authors: Lagerberg Brian
Published: April 2007

The commute trip reduction (CTR) program is an employer-based regional transportation demand management (TDM) effort initiated in Washington State in 1991. Through the CTR law, major employers in the nine largest counties are required to develop and implement TDM programs for their employees. As a result of the law, nearly 900 employers have developed programs affecting over 460,000 employees. The CTR statute requires an evaluation and periodic reports to the state legislature. The first formal report on the program's design and implementation was presented to the legislature in December 1995, thus ending the first phase of the program. To date, employers have fully developed and implemented their work-site programs, surveyed for their base year single-occupant vehicle and vehicle miles traveled rates, and completed their first measurement survey, and are assessing their ability to achieve the 1997 and 1999 CTR goals. As employers begin Phase 2 of the CTR program, they are raising concerns about some of the barriers they face in implementing the program. The effect of the CTR program on employers is considered, some of the lessons learned during Phase 1 are outlined, and how to translate these lessons into program improvements for CTR or other employer-based TDM programs is discussed.
Selection and Evaluation of Travel Demand Management Measures
Authors: Taylor Christopher J. , Nozick Linda K. , Meyburg Arnim H.
Published: April 2007

Travel demand management (TDM) measures are designed to alter the attractiveness of competing travel modes to prompt individuals to carpool or use transit instead of driving alone. Determining the best set of measures for a given area and estimating the effectiveness of the selected measures involve understanding the characteristics of the available transportation modes and of the area's travelers. The process of developing the best, comprehensive set of TDM measures for the Syracuse, New York, area and predicting the effect of those measures are described. Based on a case study of the best TDM measures and their effect in Syracuse, a procedure is presented that can be used for similar studies elsewhere. An effort is made to use data that would be available for similar studies. The evaluation tool is one that would be available in any other area. The main source of information about the travel patterns was census journey-to-work information. Additional information about employment, transit service, roadway congestion, and so forth was derived from planning reports developed by the local metropolitan planning organization. Similar reports should be available in other areas because of the strict planning provisions of the Intermodal Surface Transportation Efficiency Act of 1991. The major conclusion was that it is indeed possible to select an appropriate set of TDM measures for a given study area while relying on only limited, readily available data and tools.
Simulation of a Vehicle Impacting a Modified Thrie-Beam Guardrail
Authors: Plaxico C. A. , Hackett R. M. , Uddin W.
Published: April 2007

A three-dimensional finite-element simulation study, developed for the purpose of modeling the event of a compact automobile impacting a modified thrie-beam guardrail, is presented. The developed computational model has been used to simulate an actual field test that was previously conducted as part of a full-scale crash test program carried out under the auspices of FHWA. Results of the actual crash test are also used to "tune" the simulation model.
NCHRP Report 350 Testing of W-Beam Slotted-Rail Terminal
Authors: Mak King K. , Ross Hayes E. , Bligh Roger P. , Menges Wanda L.
Published: April 2007

Two slotted-rail terminal (SRT) designs, one for use on roadways with speed limits of 72.4 km/hr (45 mi/hr) or less and the other for high-speed facilities, were previously developed and successfully crash-tested in accordance with guidelines set forth in NCHRP Report 230. Those SRT designs have been approved by FHWA for use on federal-aid projects. However, FHWA has since adopted NCHRP Report 350 as the official guidelines for safety performance evaluation of roadside features and required that all roadside features to be used on the National Highway System be crash-tested in accordance with the NCHRP Report 350 guidelines by 1998. It is therefore necessary to modify and retest the SRT designs in accordance with NCHRP Report 350 guidelines. The modified SRT design has successfully met the guidelines set forth in NCHRP Report 350 for Test Level 3 conditions, that is, 100-km/hr (62.2 mi/hr) and the results of the crash testing. The modified SRT design has been approved by FHWA for use on the national highway system.
Effect of Light Poles on Vehicle Impacts with Roadside Barriers
Authors: Kennedy James C.
Published: April 2007

Light poles installed within the deflection zone of roadside barriers (guardrails) may influence the ability of the guardrail to safely redirect an impacting vehicle. One concern is that, during an impact, the vehicle may pivot about the relatively rigid light pole and then spin away from the guardrail back into the traffic stream in an uncontrolled, unsafe manner. A large percentage of the highway network in Ohio uses the type of guardrail and light pole configurations, in which the breakaway light poles are placed at either 15.2- or 45.7-cm (6- or 18-in.) lateral distance from the back of the guardrail, depending on one of two light pole base designs in use. These pole-guardrail systems were placed in large numbers some years ago and Ohio accident data have been inadequate to provide information to determine whether or not a problem exists with this system. Proposed highway rehabilitation and reconstruction projects can include changes or adjustments to placement of guardrails and light poles, but there was a lack of information as to whether or not the past practices possessed a problem. A study was conducted to determine if light poles have an adverse effect on the redirecting performance of guardrails. It included six full-scale crash tests involving two vehicle weight classes (2000P and 820C), two light pole base designs (AT-A and AT-X), and a typical guardrail used in Ohio [Type 5 (W-Beam)]. All full-scale tests were carried out according to the recommended procedures in National Cooperative Highway Research Program (NCHRP) Report 350. The actual vehicles used for the 2000P class were half-ton pickup trucks ballasted to simulate the weight and mass characteristics of the 2000P vehicle that is specified in NCHRP Report 350. The guardrail–light pole system was not shown to cause snagging or subsequent unstable motion of the vehicle due to impact. All vehicles exited the guardrail in a stable manner. No change in the arrangement of light poles behind the Type 5 guardrail is contemplated. The redirecting function of the guardrail was not compromised as a result of placement of the light pole behind the length-of-need. Excessive exit angle situations (according to NCHRP Report 350) occurred in three tests involving the simulated 2000P class vehicles. However, the impact conditions employed for these tests were extreme, and the likelihood of this situation occurring under everyday highway usage may be small.
Testing and Evaluation of Merritt Parkway Guiderail
Authors: Lohrey Eric C. , Carney John F. , Bullard D. Lance , Alberson Dean C. , Menges Wanda L.
Published: April 2007

A blocked-out steel-backed timber guiderail and transition on steel posts were successfully developed and crash-tested in accordance with requirements set forth in NCHRP Report 350 for Test Level 3. The timber guiderail system was developed for placement along the scenic Merritt Parkway in Connecticut. The timber guiderail and transition were constructed from rough-sawn commercial Grade 1 southern pine backed with a 10- x 152-mm ASTM A588 Grade 50 structural steel plate. The guiderail was supported by W150 x 22.5 steel posts 2 m long, spaced 3.05 m through the length-of-need section. Reduced post spacings of 0.8 m and 1.5 m were used in the transition section.
Guardrail Need: Embankments and Culverts
Authors: Wolford Dan , Sicking Dean L.
Published: April 2007

A cost-effectiveness analysis was used to study safety-treatment options for embankments and culverts on resurfacing, restoration, and rehabilitation (3R) projects. An examination of the need for cable and W-beam guardrails to shield traffic from roadside embankments and roadside culverts, respectively, was made. Average embankment and culvert accident severities were estimated using Highway Safety Information System data from Utah and Michigan. Average accident severities were calibrated through computer simulations of ran-off-road accidents. Simplified design charts were developed to allow highway engineers to quickly determine the need for cable guardrail on 3R projects.
Estimating Vehicle Roadside Encroachment Frequencies by Using Accident Prediction Models
Authors: Miaou Shaw-Pin
Published: April 2007

The existing data to support the development of roadside encroachment-based accident-prediction models are limited and largely outdated. Under FHWA and TRB sponsorship, several roadside safety projects have attempted to address this issue by proposing rather comprehensive data collection plans and conducting pilot data collection efforts. It is clear from these studies that the required cost for the proposed roadside field data-collection efforts will be very high. Furthermore, the validity of any field-collected roadside encroachment data may be questionable because of the technical difficulty of distinguishing intentional (or controlled) from unintentional (or uncontrolled) encroachments. A method to estimate some of the basic roadside encroachment parameters, including vehicle roadside encroachment frequency and the probability distribution of lateral extent of encroachments, using existing accident-based prediction models is proposed. The method is developed by utilizing the probabilistic relationships between a roadside encroachment event and a run-off-the-road accident event. With some assumptions, the method is capable of providing a wide range of basic encroachment parameters from conventional accident-based prediction models. To illustrate the concept and use of such a method, some basic encroachment parameters are estimated for rural two-lane undivided roads. In addition, the estimated encroachment parameters are compared with those estimated from the existing encroachment data. The illustration indicates that this method can be a viable approach to estimating basic encroachment parameters of interest and, thus, has the potential of reducing the roadside data collection cost.
Development of a New Guardrail System
Authors: Reid John D. , Sicking Dean L. , Faller Ronald K. , Pfeifer Brian G.
Published: April 2007

The W-beam guardrail system has been the standard in the United States since the late 1950s and has proved to perform reasonably well under most impact conditions. However, in recent years the vehicle fleet has changed to include a relatively large percentage of light trucks, such as pickups, vans, and sport-utility vehicles. These vehicles have a higher center of mass and bumper mounting height than conventional automobiles and have been shown to have higher rollover and injury rates during guardrail accidents than conventional automobiles. Standard W-beam guardrails were not designed to capture the bumper of many of these vehicles. In recognition of the potential safety problems associated with light-truck accidents, safety performance standards were recently changed with the publication of NCHRP Report 350, Recommended Procedures for the Safety Performance Evaluation of Highway Features. These performance standards require all new safety hardware to be tested with a full-size three-quarter-ton pickup to ensure acceptable performance for most vehicles in the light-truck category. In recognition of this, a guardrail system capable of capturing and redirecting a larger range of vehicle types and sizes was developed. A new guardrail system, called the Buffalo Rail, was designed with a new cross-sectional shape with an effective depth of 311 mm (compared to 194 mm for the W-beam), a rail thickness of 13 gauge, and a post spacing of 2500 mm. The safety performance of the Buffalo Rail was found to be acceptable according to the procedures and criteria recommended for the three-quarter-ton pickup truck at Test Level 3 in NCHRP Report 350.
Scenic Byways: A Review of Processes, Administration, and Economic Impacts
Authors: Sipes James L. , James A. Paul , Lindley Joan , Campbell Terrie , Gragg Rob , Harbert Clint
Published: April 2007

Since the passage of the Scenic Byways Act in 1989 and the publication of the Scenic Byways Advisory Committee Report of 1991, many states have created byways programs, joining the states that have had administered programs for years. The initial flurry of activity has retreated somewhat, and some of the original interest has waned. Yet this period offers an advantage to states such as Oklahoma that did not begin a byways program immediately after 1989-1991. What aspects of their programs have been successful? What has worked well and what has not? These questions prompted a detailed analysis of how states were addressing specific issues such as ( a) the creation, administration, and funding of a scenic byways agency, ( b) designation criteria, and ( c) the economic effects of scenic byways. The objective was to determine which ideas and modifications implemented by other states could translate to Oklahoma's setting.
Status Report of Colorado Scenic and Historic Byways Program, 1989 to 1996
Authors: Walker Steven P. , Pearce Sally , Sem John
Published: April 2007

To date, the Colorado Scenic and Historic Byways Commission and the Colorado Transportation Commission have designated 21 scenic and historic byways. Colorado's program was one of the first fully developed programs in the country and is viewed as a model by FHWA. The history of Colorado's byways program is provided, including its intent and approach, as well as an overview, description, and assessment of the program, planning efforts, products, and projects developed to date. The investment strategy and how available funds have been used and maximized is a key aspect. A detailed description of program administration and planning processes is provided. A monitoring and evaluation program is described and potential infrastructure impacts identified. Lessons learned and the program's future with consideration of available funding are discussed.
Hydrologic Data Development System
Authors: Smith Peter N.
Published: April 2007

The Hydrologic Data Development System is a prototype system of spatial data and menu-driven programs that allows user-interactive determination of hydrologic parameters and estimation of flood-frequency relationships for the design of highway drainage structures. The program employs Arc/Info, a commercial geographical information system. A data base was developed to cover the extent of Texas at a scale of 1:2,000,000 and a smaller sample area of northeast Texas at a scale of 1:250,000. The data include digital-elevation models, major highways, soil characteristics, design rainfall depth-frequency-duration, land use, stream gauge sites, hydrologic regions, and political boundaries. New tables were developed to spatially relate soil characteristics and land use to runoff coefficients used in the Natural Resources Conservation Service Runoff Curve Number method. The system employs spatial-analysis techniques to establish an outfall, to delineate drainage boundaries and flow paths using relevant digital-elevation data, and to use other data layers to determine parameters such as average watershed slope, time of concentration, area-weighted runoff curve numbers, and area-weighted design rainfall. Input files can be established and submitted to the Texas Hydraulic System computer program to determine food-frequency relationships.
PAVDRN: Computer Model for Predicting Water Film Thickness and Potential for Hydroplaning on New and Reconditioned Pavements
Authors: Huebner Richard Scott , Anderson David A. , Warner John C. , Reed Joseph R.
Published: April 2007

PAVDRN is a computer model that determines the speed at which hydroplaning will be initiated on a section of highway pavement. It is intended to be used by highway engineers before final geometric design to (a) indicate the location of the worst incidence of hydroplaning that is likely to occur on a given section and (b) to rapidly assess different geometric configurations of a section and pavement materials to select a design that will minimize hydroplaning potential. The model is based upon a one-dimensional, steady-state form of the kinematic wave equation. This equation is used in conjunction with relationships for Manning's n that account for the nature of the shallow flow over highway pavements. Ultimately, water-film thickness along a maximum flowpath length is used in empirical expressions to determine the speed at which hydroplaning is likely to occur along this path. The path is determined by analyzing the geometry of the pavement section. Five different geometric sections can be analyzed: ( a) tangent section, ( b) superelevated curve, ( c) transition section, ( d) vertical crest curve, and ( e) vertical sag curve. The user interface was written in Microsoft Visual Basic Version 3.0. It uses context-sensitive help screens. The algorithms for water-film thickness and hydroplaning potential were written in FORTRAN 77.
Increasing Rail Transit Access to Airports in Chicago
Authors: Foote Peter J. , LaBelle Sarah J. , Stuart Darwin G.
Published: April 2007

The results of two surveys of arriving and departing air travelers at O'Hare and Midway airports in Chicago concerning their choice of ground access and egress modes are reported. The purpose of the surveys was to better understand the travelers' trip purpose, trip frequency, origin and destination location, and perception of rail rapid transit as an access mode, so that promotional programs can be developed to increase this transit use. For both airports, about 15 percent of all air travelers whose ground trip-ends fell within the Chicago Transit Authority’s (CTA’s) service area used rail transit for access and egress. Rail access has been provided to O'Hare (Northwest Corridor, Blue Line) since 1984 and to Midway (Southwest Corridor, Orange Line) since 1993. The CTA has undertaken targeted promotional campaigns to increase the overall diversion of automobile travelers in both corridors to rapid transit. Such improved access to the airport increases the potential for greater market penetration. Passenger characteristics and survey methods are summarized, and the two ground access surveys are compared. The importance of express transit service as a significant consideration for managers and designers of major airports is highlighted.
Origin-Specific Visitor Demand Forecasting at Honolulu International Airport
Authors: Prevedouros Panos D.
Published: April 2007

The development of a PC-based and easy-to-use-and-update econometric model system for forecasting arrivals at the Honolulu International Airport is presented. A model system instead of a single model was designed so that differential growth rates from various origins as well as arrivals affected by curfews at the origin or the destination, or both, can be estimated. The airport system of the state facilitates the only mode of transportation into and out of Hawaii. Planning based on reliable demand forecasts is therefore essential. Separate models of arrivals from Australia and New Zealand, Canada, Germany, Korea, and the United Kingdom were specified and estimated using the Cochrane-Orcutt regression method. Several diagnostic tests were employed to arrive at the final models, as problems of correlation (over time) and collinearity (among variables) were present. Independent variables include the gross domestic product, population, monetary exchange rate, and unemployment rate of the origin countries. Historical values for the independent variables were taken from the publications of international organizations. Variables for wars that tend to affect flying security and natural disasters in Hawaii that affect the supply of tourist accommodations were included in the model specifications.
Rehabilitation and Preservation of Oregon’s Historic Concrete Coastal Bridges
Authors: McGill Galen , Shike Terry
Published: April 2007

Oregon’s Coastal Bridge Program was designed to preserve the economic and cultural resources invested in Oregon’s coastal bridges. The Oregon Coast Highway contains a significant concentration of bridges listed on or eligible for the National Historic Register. Many of these reinforced concrete structures are suffering extensive corrosion damage resulting from years of exposure to the marine environment. Oregon has developed this program to evaluate, prioritize, and preserve these magnificent bridges. Preservation of these bridges has relied on the innovative application of cathodic protection technology. This new technology has been applied successfully through a project design and construction process that includes ongoing interaction among design engineers, researchers, construction project management personnel, and contractors.
Expert System Architecture for Computer-Aided Environmental Analysis
Authors: Adler Jeffrey L. , Franks Tom , Nelson Debra , Benware Thomas , Ivey Mary , McVoy Gary
Published: April 2007

Expert systems can be useful tools to assist and guide practitioners through particularly difficult and complex decision-making environments. The process of assessing the requirements and conceptualizing an expert system architecture for the New York State Department of Transportation to enhance its environmental analysis functions is described. Using expert system techniques presents a proactive and innovative approach to systematize and improve the environmental process within transportation design. Among the system’s objectives are to treat effectively the logic and inference process associated with the breadth and depth of environmental analysis resource areas, promote compliance with federal and state environmental requirements, enhance project management through estimating staff resources, and be responsive to the needs of multiple user classes to include environmental staff, designers, planners, and managers.