bluuebunny/crossref_metadata_2025 huggingface dataset:
Assessment of Pavement Life at First Full-Scale Accelerated Pavement Test in Louisiana
Authors: Romanoschi S. A. , Metcalf J. B. , Li Y. , Rasoulian M.
Published: April 2007

The first full-scale accelerated pavement testing experiment in Louisiana began in February 1996. The purpose was to evaluate the historically prevalent flexible crushed-stone and in-place soil cement-stabilized base construction in comparison with several alternative base construction materials and construction processes for pavements designed for a semitropical climate. More than 6 million equivalent single-axle loads (ESALs) were applied to nine test lanes in the three phases of the project. The full-scale loading was provided by an accelerated loading facility (ALF) machine, the second of its type in the United States. Surface deflection, longitudinal and transverse profiles, surface cracking, stresses and strains in the pavement structure, as well as environmental conditions were monitored during testing. The initial findings are presented in relation to rutting, roughness, cracking, layer modulus, and stress and strain evolution. In order to account for the localized deterioration of some lanes, a method based on statistical survival analysis theory was used to assess the pavement life. Reasonable agreement was observed between the life of the tested structures and the life predicted by the current procedure, on the basis of the 1993 pavement design guide from AASHTO, for the crushed-stone base pavements. The observed lives of the pavements with a soil cement base were shorter than the predicted lives.
Axle Spacing and Load Equivalency Factors
Authors: Gillmann Ralph
Published: April 2007

Weigh-in-motion (WIM) systems measure the axle spacings and axle loads for every vehicle in the traffic stream. There is a great need to estimate load equivalency factors (LEFs) from these WIM data. LEFs are approximately a fourth-power relation relative to a standard axle load. However, this ignores axle spacings, which have a significant effect. The American Association of State Highway and Transportation Officials derived LEFs for single and tandem axles, and these were extended to triple axles. Some have extended LEFs to quadruple axles, though there is no common agreement about this. However, larger axle groups also occur. Moreover, WIM data from the United States reveal a great variety of irregular and unusual axle spacings, and procedures to estimate LEFs for them are completely lacking. An attempt is made to rectify this and to estimate LEFs for vehicles with any axle spacing. An LEF adjustment method is developed, and examples are given of its use.
The Contractor’s Competitive Edge: Means and Methods
Authors: Tirolo Vincent
Published: April 2007

Design engineers traditionally have been responsible for the design of a project. They also have provided performance specifications for the protection of adjacent property owners, existing facilities, and so forth. Design engineers may also provide construction oversight and inspection. The role of the contractor has been to develop the means and methods and to construct the project in accordance with the performance requirements given in the contract documents. Unfortunately, these traditional roles have changed over the past two decades. On complex projects, design engineers often provide “suggested methods of construction.” However, design engineers are not constructors. Often suggested methods of construction are overly conservative and unimaginative. It is a myth that suggested methods of construction protect the owner from unscrupulous contractors. Unscrupulous contractors will always find a way to claim that suggested methods of construction are misleading or unconstructable. Most contractors feel constrained to bid the suggested methods of construction to avoid the risk of having their alternative means and methods rejected by the designer because it “does not provide the same level of comfort” as the suggested method. Therefore, suggested methods of construction reduce competitiveness during the bid process, permit unqualified contractors to bid the project, and increase construction costs to the owner. When a contractor bids a project, the most important single consideration is schedule. Means and methods and repetitive operations drive the contractor’s schedule. Means and methods can be influenced by issues such as adverse ground conditions, material deliveries, coordination with adjacent contractors, agency approvals, weather conditions, and many other factors. These issues add uncertainty and risk to the project. Contractors have a better understanding of the major areas of construction uncertainty than owners and design engineers. If a project is complex enough to require suggested methods of construction, it is complex enough to require contractors to be prequalified. Prequalifying contractors should eliminate the need for suggested methods of construction. It is recommended that developing the “means and methods” of constructing a project be left in the hands of qualified contractors. Design-build contracts also are an effective way of providing contractor input early in the design process. As such, most design-build projects result in lower overall cost with dramatically reduced time from design to the completed project. Three heavy construction projects are discussed here in which creative construction engineering plays an important role in the success of the project. On all three projects the suggested method of construction in the contract documents was significantly modified. These projects include New York City Transit’s 63rd Street Connection Tunnel, Boston’s Central Artery Project, and the Long Island Expressway Connector and Distribution project under the Long Island Railroad in New York City.
Field Tests of a Large-Span Metal Culvert
Authors: Webb Mark C. , Selig Ernest T. , Sussmann Jeanne A. , Mcgrath Timothy J.
Published: April 2007

Full-scale field tests were conducted on a 9.5-m (31-ft 2-in.) span low-profile arch culvert to provide input for development of improved large-span culvert load and resistance factor design specifications. The test structure was constructed of 5.5-mm (0.215-in.) thick black steel plate with 152 × 51 mm (6 × 2 in.) corrugations. No supplemental circumferential or longitudinal stiffeners were added. Two tests were conducted with SW backfill material, one each compacted to 87 and 92 percent of maximum standard Proctor density. Live-load tests were conducted with a truck with tandem axles loaded to 156 kN (35,000 lb) per axle at depths of fill of 0.3, 0.6, and 0.9 m (1, 2, and 3 ft). Measurements were made of culvert deformation, culvert strain, culvert-soil interface pressure, soil density, soil strain, foundation movement, and temperature. Thrusts and moments were determined from the culvert strain.
Flexibility Factor or Pipe Stiffness: Significant Stiffness Considerations
Authors: Schluter James C. , Shade James W.
Published: April 2007

Stiffness requirements for metal and other flexible pipes are often misunderstood and misused. Stiffness, which often is confused with strength, is defined in several ways that do not directly compare. The stiffness of metal pipes is traditionally limited by a calculated flexibility factor. Alternatively, plastic pipes are usually rated in terms of laboratory-measured pipe stiffness. However, the AASHTO design method uses a calculated flexibility factor for plastic pipe design that appears to relate to metals. Laboratory-measured “stiffness” is used here to investigate the geometry, material, and environmental factors that must be considered to evaluate functional stiffness and compare pipe performance.
Minnesota Department of Transportation Overload Field Tests of Standard and Standard Installation Direct Design Reinforced Concrete Pipe Installations
Authors: Hill James J. , Kurdziel John M. , Nelson Charles R. , Nystrom James A. , Sondag Michael S.
Published: April 2007

The design, manufacture, and installation of concrete pipe have changed significantly under the new standard installation direct design (SIDD) beddings. The Minnesota Department of Transportation (MnDOT) initiated a research project to evaluate the benefits of these new installations in conjunction with state-of-the-art means for determining soil stiffness and, thereby, its effect on concrete pipe performance. The methodology used to develop the test installations, how the pipes were instrumented, and the significance of soil stiffness relative to soil density is described. The performance of concrete pipe under both the SIDD and MnDOT standard installations, the resulting variability found with specific soils, and recommendations for concrete pipe design and installation are also addressed.
Calculating Loads on Buried Culverts Based on Pipe Hoop Stiffness
Authors: Mcgrath Timothy J.
Published: April 2007

Evaluating the hoop compression capacity of buried pipe, whether for total stress, local buckling capacity, or general buckling capacity, requires an accurate design model to compute the compressive thrust in the pipe wall. Flexible pipe has traditionally been designed based on the assumption that vertical soil load is the weight of soil directly over the pipe, known as the “soil prism load.” Field experience and research have shown that some pipe with low cross-sectional area and low modulus of elasticity can be buried at depths much greater than calculated by using the soil prism load, indicating that this load assumption is too conservative under some conditions. Investigation using the Burns and Richard elasticity solution for a circular tube embedded in an elastic medium shows that the ratio of the soil stiffness to the pipe hoop stiffness (EA/R) is often the controlling factor in determining the load on a buried pipe instead of the flexural stiffness of the pipe. The significance of the hoop stiffness factor for determining load on flexible and rigid buried pipe is explored here and development of a simplified design model for predicting loads based on the Burns and Richard theory is presented. The proposed equations are consistent with past practice and with tests showing that pipe with low hoop stiffness can carry far greater depths of fill than predicted by past practice.
Proposed Revisions to AASHTO Standard Specifications for Structural Supports for Highway Signs, Luminaires, and Traffic Signals
Authors: Fouad Fouad H. , Nunez Edgar , Calvert Elizabeth A.
Published: April 2007

The 1985 AASHTO Standard Specifications for Structural Supports for Highway Signs, Luminaires, and Traffic Signals (referred to here as the current Supports Specifications) has been revised in its entirety with significant additions to its content and scope. This work is the result of an extensive research study performed under NCHRP project 17-10. The main objective of the study was to update the previous edition of the Supports Specifications based on the most recent state-of-the-art information for the design and use of structural supports. Considerable effort was made to specify the best practice, realizing the characteristics and limitations of each material. From a design safety standpoint, all materials for structural supports were treated equitably. Safety, aesthetics, and economy were three main guidelines in developing the provisions of the Supports Specifications, but manufacturing practices and experiences were also considered. The proposed specification is presented in a specification/commentary side-by-side format that will enable the engineer to review with ease the basis of Supports Specifications’ provisions. References are updated to provide a resource for the most recent research studies related to the structural behavior and performance of structural supports. An extensive table of contents is provided to allow easy reference and quick access to various provisions of the Supports Specifications. The purpose of this report is to present highlights of the proposed revisions to the specification. The supporting information, scope, and basis for the proposed changes are also discussed.
Flow Characteristics at Freeway Work Zones and Increased Deterrent Zones
Authors: Polus Abishai , Shwartzman Yechezkel
Published: April 2007

Traffic-flow characteristics were studied at two work zones on suburban freeways and at a third freeway site where a police patrol car, easily noticed by drivers, was parked on the right shoulder. The purpose of the study was two-fold: ( a) to estimate the speeds, headways, and capacities of sections in which some lanes were temporarily closed to traffic because of relatively short construction operations, and ( b) to assess the impact of increased, visible police deterrents on traffic flow, capacity, and safety. Calculated average flow rates, obtained from 1-min observations, were similar to values suggested by the Highway Capacity Manual at Site 1 but considerably less at Site 2. The lower values at Site 2 are attributed to the transfer of vehicles from the northbound to the southbound lane and to the resulting “constrained” operation that resulted because of a temporary barrier near oncoming traffic. The presence of a police patrol car on the shoulder at Site 3 created a deterrent to drivers, resulting in reduced average headways (and therefore increased density) and reduced headway variability. Because the volumes remained about constant, the resultant space-mean speeds also dropped. The importance of the flow stability—obtained by warning and advisory signing, the gradual closure of lanes, and a visible deterrent such as a police presence—is emphasized. Further research is suggested on the optimal slope and length of lane-closure tapers on freeway work zone approaches, the capacity of other combinations of lane closures, and the safety effects of traffic deterrence caused by police presence.
Work Zone Speed Limit Procedure
Authors: Migletz James , Graham Jerry L. , Anderson Ingrid B. , Harwood Douglas W. , Bauer Karin M.
Published: April 2007

A procedure was developed for determining work zone speed limits usable during the design or construction phases of a roadway construction project. The procedure classifies work zones by the potential hazard present, as represented by the location of work activities or traffic controls in relation to the traveled way, instead of the prevailing speed of traffic. Research by others showed that accident rates increase with deviation from average speed. The most desirable work zone speed limit policy minimizes the increase in accident rate during the construction period. Accident and speed studies showed that the minimum increase in accident rate and speed variance occurred in work zones with a 16 km/h (10 mph) reduction in the work zone speed limit. In a follow-up study, the procedure was implemented on a trial basis in work zones with speed limits up to and including 105 km/h (65 mph). Research showed that the procedure was implementable and can be used to establish speed limits that maximize traffic safety in work zones. Guidelines were developed for implementing the procedure.
Driver Performance Comparison of Fluorescent Orange to Standard Orange Work Zone Traffic Signs
Authors: Hummer Joseph E. , Scheffler Craig R.
Published: April 2007

Some agencies use durable fluorescent orange sign sheeting on warning signs in work zones. The literature shows that such sheeting is more conspicuous than standard nonfluorescent orange sheeting, but no one has yet demonstrated that the greater conspicuity leads to operational changes or fewer collisions. To investigate that link, operational studies were conducted in seven long-term North Carolina work zones with left-lane drops on multilane highways. The before-and-after with control experiment design was likely immune from common experimental flaws. Five operational measures were collected manually at the beginning of the approach to the work zone, the taper, and midway between the beginning and the taper. Fluorescent orange signs were found to cause some changes, primarily positive, in driver behavior. With fluorescent signs, there were somewhat fewer traffic conflicts, the percentage of vehicles in the left lane at the midpoint was lower, and trucks moved out of the left lane sooner. Mean speeds increased slightly, but usually not significantly, with fluorescent signs, but speed variances tended to decrease with fluorescent signs. The operational changes observed should mean that work zones similar to those in the experiment would experience a small reduction in collisions with fluorescent orange warning signs. Use of fluorescent orange sheeting on warning signs is recommended in work zones like those in this experiment and in other types of work zones where warning drivers is as critical or more critical than it was in this experiment.
A Knowledge-Based GIS Approach to the Evaluation of Design Consistency of Horizontal Alignments
Authors: Faghri Ardeshir , Harbeson Mark
Published: April 2007

Design consistency is an important safety feature in the field of highway design. The driver will anticipate the alignment of a highway based on the highway section that he or she has already traveled, and unfamiliar elements that are introduced could cause serious safety problems. Much research has been performed and many different mathematical and empirical models have been formulated to predict and evaluate roadway design consistency. A knowledge-based expert system is combined with a Geographic Information System (GIS) to evaluate horizontal alignment design consistency on U.S. highways. The GIS was chosen because of its vast information storage and manipulation capabilities; it can store human expertise on a subject and suggest solutions to a problem. By evaluating the changes in the degree of curve for each consecutive element of the roadway, the program is able to successfully evaluate the consistency of horizontal alignment. The program shows a high success rate when tested on hypothetical roadways with known consistency ratings. It was applied successfully to an actual state highway in Delaware as well.
Operating Speeds on Curves With and Without Spiral Transitions
Authors: Passetti Karl A. , Fambro Daniel B.
Published: April 2007

Although the design policies of many countries encourage the use of spiral transition curves, questions exist about whether they have any benefit in roadway design. In addition, United States speed prediction models do not account for the presence of spiral transitions. To determine if spiral transitions affect the speed at which vehicles traverse horizontal curves on rural two-lane roadways, speeds of free-flow passenger cars on spiral transition curves were compared with speeds of free-flow passenger cars on circular curves that had similar geometric characteristics. Operating speeds and geometric data were collected at 12 spiral transition curves and 39 circular curves in six states. Using regression techniques, it was concluded that spiral transitions did not significantly affect the 85th percentile speed of drivers on horizontal curves. Analysis of the cumulative speed distributions for different curve radii showed that speeds were higher for spiral transition curves than for circular curves for a 145-m radius (smallest radii studied); however, no data were available to test the hypothesis further. It is believed that spiral transition curves may affect vehicle speeds as the curve radius decreases. It was concluded that spiral transitions did not produce significant differences in passenger-car operating speeds.
Evaluation of Zero-Length Vertical Curves
Authors: Wooldridge Mark D. , Nowlin R. Lewis , Parham Angelia H.
Published: April 2007

To evaluate the use of zero-length vertical curves with respect to Texas Department of Transportation design practice, construction results, and vehicle dynamics, and to compare zero-length vertical curves with minimum-length design vertical curves, 20 zero-length vertical curves and 15 minimum-length vertical curves were evaluated. Evaluations performed included examinations of sight distance for zero-length vertical curves, surveying roadway profiles, and measuring vertical accelerations. Sight distance criteria were found to be generally inapplicable below 2 percent for sag vertical curves. For crest vertical curves, sight distance criteria were inapplicable below 1 percent for design speeds of 90 km/h or less and inapplicable below 0.5 percent for design speeds of 100 to 120 km/h. The results of vertical acceleration testing showed that, below 0.5 percent grade change, no practical difference was found between zero-length and minimum-design-length vertical curves. Between 1.0 and 0.5 percent grade change, significantly higher accelerations were measured for high-speed tests on zero-length vertical curves. Finally, it was found that zero-length vertical curves were more likely to meet drainage grade requirements than minimum-design-length vertical curves were.
Expanding the Urban Transportation Infrastructure Through Concession Agreements: Lessons from Latin America
Authors: Rodríguez Daniel A.
Published: April 2007

Driven by fiscal constraints and disappointment with the performance of state-provided services, national and subnational governments have turned to the private sector for solutions in financing, constructing, and providing transportation services. Key concession package features and their effect on reaching closure in urban transportation agreements are analyzed. Case studies drawn from the major attempts to develop urban transportation infrastructures in Latin America through concession agreements are considered. Results indicate that features common to large infrastructure projects (e.g., high capital costs and asset indivisibility), urban transportation (e.g., high intermodal competition and the uncertainty of accurate demand forecasts), and developing countries (e.g., incipient financial markets) are negatively associated with reaching successful financial closure of the agreements. These results suggest that governments should pay close attention to risk allocation in a concession plan. By illustrating the intricate interdependencies among package features and how complex and tailored to a specific context successful concession agreements must be, it is concluded that governments face more rather than fewer decisions when developing an infrastructure through concession agreements.
Forecasting Toll Revenues for Fully Electronic Highways Operating Under Transponder and Video-Imaging Systems
Authors: Mekky Ali
Published: April 2007

For many years, 407 ETR, a four- to six-lane tollway in the Greater Toronto Area, has been considered a relief for Highway 401, the busiest highway in North America, used by more than 1 million vehicles per day. At present, about 67 km of the tollway is operational. Is 407 ETR operating at its maximum revenue potential—and how would this revenue potential change over the next 6 years? Forecasting toll revenue for a fully electronic highway is not easy, since it involves modeling two classes of drivers, who value their times differently but use the highway simultaneously. These two classes consist of drivers who use transponders (TDs) and those who do not—video drivers (VDs). VDs pay $1.00 more than TDs for the same trip. Accordingly, VDs have a higher value of time compared with TDs. Adjustments to the model to deal with these classes of drivers and their values of time are described. Elasticity analysis has shown that TDs are slightly more sensitive to toll changes than VDs. It is concluded that, currently, during the a.m. peak period, the system is operating at its optimal point of gross revenue. In 2004, to operate at the maximum gross revenue level, the variable toll rate should more than double; the revenue also will more than double.
Assessing the Economic Value of the Transportation Network
Authors: Bedi Nilam , Gillen David
Published: April 2007

Estimates of the value of the highway system are presented. To develop new and better management strategies, including pricing, the change in value to those who use the system needs to be known. In contradistinction to other literature on the subject, first, a willingness-to-pay approach is used to measure the value of the system and, second, the value to the household sector—as well as to the industrial and commercial sectors—is included. Two approaches are described and compared. The first takes the standard view that the value of the roadway system is the present value of the capital stock. This is a measure of the opportunity cost of capital invested in highways. The second approach develops a measure of the value of marginal product of transportation ( VMPT). This is a flow estimate of the demand for transportation by those who use it as input. The value is measured from the derived demand curve. An indicator of the demand for transportation by households is computed similarly by estimating an expenditure function. The sum of these two derived demands is the full value of the system. A conventional capital stock measure shows the system is worth approximately $12.5 billion (1986 dollars). However, this measure is low when compared with what are termed “use measures.” When a marginal revenue product function for highway capital is constructed, the value of the current system to users is—on the production side—$14.8 billion, but the stock measure is less. The fundamental difference is that the use measure includes the surplus accruing to highway users. The same conceptual model is used to obtain an estimate of consumer or private valuation of the highway system. This has not been included previously in measures of value; it amounted to approximately $26 billion. When aggregated with production values, the difference between the conventional, stock approach and the consumer-and-producer valuation approach is—again expressed in 1986 dollars—$12.5 billion versus approximately $41 billion.
Induced Traffic and Induced Demand
Authors: Lee Douglass B. , Klein Lisa A. , Camus Gregorio
Published: April 2007

Although terms such as “induced demand” and “latent demand” have been used in transportation planning for several decades, the concept of induced demand has not been precisely defined nor has it been translated into an operational form suitable for modeling. This paper defines “induced” as referring to a movement along a travel demand curve, in which the price dimension includes travel time and other user costs. Selecting the relevant demand curve is then an analytic choice. For FHWA’s Highway Economic Requirements System (HERS) model, movement along the within-period, short-run demand curve is referred to as “induced traffic,” while movement along the between-period longrun demand curve constitutes a shift in the short-run demand curve and is referred to as induced demand. The model employs this definition to evaluate highway improvement projects using benefit-cost analysis, incorporating effects of short-run traffic volume on changes in the generalized price, as well as effects of long-run land use and other economic feedback. These features were used in the HERS model to prepare the 1997 “Conditions and Performance” report to Congress.
Incorporating Toll-Lane and High-Occupancy Toll-Lane Effects into the Dallas System Planning Methodology
Authors: Brunk John C. , Middleton Mark D.
Published: April 2007

The Dallas System Planning Methodology (SPM) was developed jointly by the Texas Department of Transportation, the North Central Texas Council of Governments, Dallas Area Rapid Transit, and the Texas Transportation Institute as a transportation-corridor and system-analysis tool to bridge the gap between regional planning and detailed corridor design. SPM allows for the examination of peak-hour person movement for different types of facilities within a corridor and estimates the associated public costs (e.g., right-of-way, construction, operation, congestion, and environmental costs). The objective of SPM is to find the alternative with the lowest total public cost. It was decided to enhance SPM by adding toll lanes and high-occupancy toll (HOT) lanes as alternatives for evaluation against other combinations of general-purpose lanes, high-occupancy vehicle (HOV) lanes, and express lanes. The results of this project confirmed previous findings that low- and moderate-demand facilities are best served by improving general-purpose lanes in the corridor and, in some cases, by adding express lanes. Using the criteria of lowest total public cost, the evaluation of toll lanes in the test corridors showed that congested corridors with all toll lanes or with combinations of general-purpose and toll lanes did not perform as well as the alternatives, which included a combination of general-purpose and HOV lanes. However, the alternatives that combined general-purpose lanes with HOT lanes tended to perform as well as—and in some cases, slightly better than—HOV lanes.
Growing To Meet the Challenges: Emerging Roles for Transportation Management Associations
Authors: Loveless Shirley Morrison , Welch Jill Sebest
Published: April 2007

Widely varying in organizational form and function, transportation management associations (TMAs) offer the flexibility—and increasingly, the expertise—to assist local residents and businesses with emergency transportation problems (e.g., caused by a transit strike). With departments of transportation and metropolitan planning organizations, TMAs can plan for long-term and regionwide transportation needs. The public-private sector partnerships embodied by many TMAs provide several potential benefits, including a ready organizational structure for a closer dialogue between government agencies and transportation users; familiarity with local needs and problems, a knowledge of technical issues; and a broad base of human, financial, and technical resources with which to devise and implement solutions to transportation needs and problems. TMAs have come a long way from being merely employee organizations oriented to trip reduction. Today, TMAs engage in everything from public education, to working with local economic development organizations on enhancing a region’s attractiveness and competitiveness, to running local transportation systems. In the 21st century, the geographic information system and intelligent transportation system capabilities many TMAs already possess will enable them to take on greater roles in improving the transportation networks in their regions and in integrating transportation planning with land-use and economic-development planning. Typical and innovative activities currently undertaken by TMAs are described and some of the valuable roles TMAs can play in the future are discussed.
Tennessee Department of Transportation’s Vision 2000: Reengineering the Project-Development Process
Authors: Brown Barbara Z. , Marston Janice J.
Published: April 2007

The Tennessee Department of Transportation (TDOT) is one of the largest agencies in the Tennessee state government. It is responsible for maintaining and managing an integrated transportation system as well as awarding contracts for construction and maintenance. TDOT’s concern is to fulfill its obligations to the public by providing a system that functions well and is safe and cost-effective. Like other government agencies, TDOT faces strong pressure from its stakeholders to become more efficient in a changing environment. Technological advances, management methodologies that have shifted from function-oriented to process-oriented, and a new cost-awareness based on these same trends are some of the issues that the department is currently addressing with support from the professional services firm of PricewaterhouseCoopers (PwC). In their strategic planning, TDOT executives determined that the time had come for radical change through business process reengineering (BPR). BPR calls for a full-fledged effort, analyzing processes as the core task in the reengineering. TDOT began by focusing on the project-development process for new construction. Once goals were determined, a series of steps followed, including surveying the users of the various processes to establish requirements and expectations, establishing key baseline measurements, and comparing reengineered processes with best-in-class organizations. For the reengineering effort to succeed at TDOT, a close collaboration was maintained between the TDOT subject-matter experts and BPR, change-management, and information-technology experts from PwC. Successful BPR will lead to more improvement efforts in TDOT.
Developing a Proposal for a Multi-User Intermodal Freight Terminal as a Public-Private Partnership: Lessons Learned About Public and Private Perspectives, Timing, and Roles
Authors: Barton James E. , Selness Cecil L. , Anderson R. John , Lindberg Donna L. , Foster Norman S. J.
Published: April 2007

Intermodal rail terminals are an important part of an integrated freight transportation system. The location of intermodal terminals often has depended on where railroads had spare land adjacent to freight-rail lines. But many of these locations are less than ideal in terms of surrounding land uses and offer little scope for expansion as intermodal traffic grows. A study undertaken in Minnesota to evaluate the need for new or expanded intermodal terminal facilities in the Twin Cities metropolitan area is described. The process was funded by the metropolitan planning organization for the Twin Cities region, the state department of transportation, and three private railroad carriers. It involved a series of studies to determine the market for an intermodal facility, to locate a site and develop a proposal for a multi-user terminal, and to assess the terminal’s economic benefits for the region. Several lessons were learned during this public-private partnership process; these are useful for other metropolitan areas considering freight needs. The public and private sectors bring different perspectives to the development process, and coordinating their decision making is a challenge. It is crucial to obtain and to maintain appropriate and timely access to decision makers. The competitive positions of carriers must be assessed and the project’s impact on the relative market share among them will be critical. Given the lack of support by the railroads to develop a joint-use intermodal facility, as recommended in the study, neither the railroads nor the development community was willing to implement the project.
Formulation of a Transportation Problem by Using Existing Data: Case Study in Northeastern Illinois
Authors: Lupa Mary R. , Yoder Supin L. , Padgette Robert , Sriraj P.S.
Published: April 2007

Existing data sources, in lieu of primary data collection, can provide an excellent means of defining a transportation problem. In this study, a corridor in northeastern Illinois was analyzed using several existing databases. This analysis provided a setting in which tools could be refined for special tasks, including developing a framework for problem definition, utilizing spatial analysis for problem definition, using survey data variables fully, and defining a workable approach to estimating daily airport trips.
Neural Networks as Alternative to Traditional Factor Approach of Annual Average Daily Traffic Estimation from Traffic Counts
Authors: Sharma Satish C. , Lingras Pawan , Xu Fei , Liu Guo X.
Published: April 2007

Presented in this paper is a comparison of the neural network approach and the traditional factor approach for estimating annual average daily traffic (AADT) from 48-h sample traffic counts. Minnesota’s automatic traffic recorder (ATR) sites are investigated. The traditional AADT estimation approach involves application of volume adjustment factors to sample counts. The neural network model used in this study is based on a multilayered, feed-forward, and back-propagation design for supervised learning. The results of AADT estimation from a single shortperiod traffic count indicate that as compared with the neural network approach, the estimation errors for the factor approach can be lower under a scenario in which ATR sites are grouped appropriately and the sample sites are correctly assigned to various ATR groups. Unfortunately, the current recommended practice offers little guidance on how to achieve the assignment accuracy that may be necessary for obtaining reliable AADT estimates from sample counts. The advantage of the neural network approach is that classification of ATR sites and sample site assignments are not required. The neural network approach can be particularly suitable for estimating AADT from two or more shortperiod traffic counts taken at different times during the counting season.
Evaluating Role of Distance and Location in Statewide Travel Demand Forecasting by Using American Travel Survey
Authors: O’Neill Wende A. , Fulton Philip N. , Brown Eugene
Published: April 2007

The focus of this initial study is on the role of distance and location in long-distance passenger travel and specifically how these affect mode choice. Distinguishing between short-and long-haul travel is one method for selecting a mode choice model structure. According to the literature, distances that define short-haul travel should exhibit competition among the modes, whereas long-haul travel distances will exhibit dominance of a single mode, generally air travel. In the literature, some values have been suggested [400 km (250 mi), 800 km (500 mi), 992 km (620 mi), etc.]. This study considers the mode shares for five states to determine ( a) if these values emerge to distinguish between competitive and noncompetitive mode share distance ranges and ( b) if competitive and noncompetitive mode share distance ranges are consistent across different states. The American Travel Survey (ATS), collected in 1995 by the Bureau of Transportation Statistics, is used.
Analysis of Global Positioning System-Based Data Collection Methods for Capturing Multistop Trip-Chaining Behavior
Authors: Yalamanchili Lalit , Pendyala Ram M. , Prabaharan N. , Chakravarthy Pramodh
Published: April 2007

An evaluation is presented of the effectiveness of Global Positioning System (GPS) data in capturing complex travel patterns characterized by multistop trip chains. This evaluation is made by analyzing tripchaining patterns for a sample of individuals from whom travel data were collected using an innovative GPS device that was fitted to one of their household vehicles. By tracking the movements of household vehicles and automatically recording their locations, it is potentially possible to capture short, intermediate, and infrequent trips that would have been missed in a traditional travel diary survey. The primary objective of the study was to evaluate the effectiveness of GPS in capturing such trips. A secondary objective was to examine whether GPS trip data are suitable for analyzing trip-chaining behavior in the context of typical activities that people pursue outside the home. Descriptive statistical analysis techniques are used to explore trip-chaining patterns of individuals and model the propensity of linking various typical out-of-home activities in home-based chains. The results indicated that GPS data collection is more effective in capturing activity-linking behavior but merits some refinement to minimize the amount of missing data.
Geographic Information System Methodology for Assessing Growth Effects of Highway Improvements
Authors: Sanchez Thomas W. , Dueker Kenneth J. , Rufolo Anthony
Published: April 2007

A methodology is presented to assess the induced land use effects of state highway improvements on urban development patterns. The methodology is applied to the case study city of Hillsboro, Oregon, and illustrates a framework for data management and analysis. Temporal land use characteristics and spatial measures are used as predictors of urban development activities resulting from highway accessibility improvements. A logit regression analysis tests the significance of these variables in predicting the locations of urban development over time. The primary objective of this research is to identify the relationship between capacity-increasing highway improvements and changes in urban development. The analysis provides quantifiable indicators that describe the urban development trends associated with the city of Hillsboro.
Dynamic Emergency Evacuation Management System Using Geographic Information System and Spatiotemporal Models of Behavior
Authors: Alam Sajjad B. , Goulias Konstadinos G.
Published: April 2007

In this paper a new emergency evacuation management system is presented that is behavior oriented, sensitive to land use patterns, and flexible, and can be implemented to produce practically meaningful evacuation plans. The system integrates dynamic behavioral patterns and transportation network and regional land use information using database management system and geographic information system software. To do this, activity participation by individuals is modeled using a microscopic approach, detailed land use patterns at the level of the room in each building of a small area, and a flexible system structure to incorporate future model developments. In addition, a practical framework is designed using a variety of existing databases, and information gaps are closed by additional data collection. The results in this study provide evidence of the feasibility for such an extremely microscopic regional planning approach with existing software.
Architecture Development for Web-Based Geographic Information System Applications in Transportation
Authors: Ran Bin , Chang Ben P. , Chen Jerome
Published: April 2007

A geographic information system (GIS) is a computer-based system that integrates computer software and hardware to collect, store, and analyze objects and phenomena for which geographic location information is critical to the analysis. A variety of transportation management and planning applications can benefit from the abundant information contained in a GIS. Advances in information technology and the Internet enable the once resource-intensive GIS transportation application to be widely available. Transportation agencies and companies are publishing these applications on the Internet and offering travelers convenient trip-planning features and traveler information. Proposed in this paper is a three-tier architecture for implementing GIS database applications on the Internet. This architecture uses a platform-independent Java applet as the front end for the client. The Java applet can run in any Java-enabled web browser, regardless of the operating system used. This capability simplifies the deployment issue. The Java applet is also capable of performing more sophisticated computations and interactions than those of static Hypertext Markup Language (HTML) pages. Within the domain of the three-tiered information system, a middleware server is proposed to serve as the interface between the client request and the GIS database for data communication. A prototype three-tiered client server application is developed based on the proposed architecture. The client side is an interactive map applet, and the server provides a shortest-path search function and a real-time traffic information service to the client. The information request by the client is retrieved from the GIS database.
Using the Internet To Improve Long-Distance Travel Data Collection
Authors: Polak John , Plaxton John , Jackson Paul G. , Wofinden Diana
Published: April 2007

Long-distance travel behavior is an increasingly important topic of study in Europe. However, the collection of information on long-distance mobility presents particular methodological difficulties. At the same time that these new challenges are emerging, the development of the World Wide Web (WWW) is opening up new technological opportunities. The objective of this paper is to describe work currently under way at Imperial College to develop a WWW-based travel survey tool for the collection of long-distance travel data. In the first section of the paper the methodological difficulties associated with the collection of information on long-distance travel behavior are briefly outlined. Then a taxonomy of computer-based travel survey methods is presented. This taxonomy is used to identify a number of different possible Internet-based survey approaches, and the potential methodological advantages and disadvantages of each approach are discussed. After the key elements of the Internet travel diary application ( i TDA) are set out, the results of a series of small-scale cognitive laboratory studies undertaken to investigate the effect of this new method of data collection on respondents are presented. Finally, some overall conclusions from the work to date are presented, and the implications for future research are discussed.
System for Logical Verification and Inference of Activity (SYLVIA) Diaries
Authors: Arentze Theo , Hofman Frank , Kalfs Nelly , Timmermans Harry
Published: April 2007

The calibration of activity-based models requires the collection of activity diaries. Although activity diaries offer some potential advantages over conventional travel surveys, they involve a substantial burden on respondents, who are prone to making mistakes. Consequently, activity diaries tend to contain incomplete information and many inconsistencies, which is a serious problem because activity-based models require consistent and complete diary information. However, many logical relations can be imposed on the various choice dimensions underlying activity diaries, and further logical constraints and relations can be derived by combining activity diaries with data about the physical and transportation environment and the institutional context. Several rules may then be used to verify the consistency of observed activity diaries and to induce complete activity diaries in the case of missing information. Since the choice dimensions underlying activity diaries are highly interrelated, the links between the rules may become rather complex, implying that algorithms are required to induce consistent and complete activity diaries. Moreover, in many situations, alternative rules may be imposed. To support this task, an interactive computer system for the logical verification and inference of activity (SYLVIA), written in C++, has been developed. The system was primarily built to support the calibration of the ALBATROSS model, an activity-based model currently under development for the Dutch Ministry of Transport, Public Works and Water Management, but it is sufficiently generic to verify other activity diaries.
Blending Charts Based on Performance-Graded Asphalt Binder Specification
Authors: Soleymani Hamid R. , Bahia Hussain U. , Bergan Arthur T.
Published: April 2007

Blending charts are used to predict properties of blended asphalt binders (mixture of an asphalt binder with other asphalt binders or modifiers) on the basis of properties of its components. These charts can be used to produce specific grading asphalt binder with blending available materials. In addition, they are used to select proper type and amount of asphalt binder or recycling agent in the design of recycled asphalt mixtures. Current blending charts are based on traditional asphalt grading parameters, such as viscosity and penetration. With the expansion of use of the SUPERPAVE system for design of asphalt mixtures, it is necessary to develop new blending charts based on performance-graded (PG) asphalt binder parameters. The main objective of this research was to characterize blended binders with the PG testing parameters, such as G* (complex shear modulus), δ (phase angle), S (stiffness), and m-value (creep rate). Ten different blended asphalt binders were characterized with the PG grading system. A linear relationship was found accurate enough for prediction of PG parameters of blended binders with proportion of new asphalt binder or recycling agent in blends. Two types of blending charts can be used on the basis of PG performance criteria or temperatures at which PG criteria were satisfied. The findings can be used for selection of recycling agents for asphalt recycling projects and for producing specific PG binders by blending available asphalt binders.