With rising road construction and maintenance costs and the lack of productivity improvement, automated road construction and maintenance equipment will provide an attractive alternative for the execution of routine work tasks in the future. This paper reviews the typical tasks applicable to this domain, as well as existing and future automated equipment for task execution. The distinction between numerically controlled (NC) machines and autonomous equipment is discussed based on task requirements and machine capabilities. Core technologies for automated equipment are reviewed. Examples of existing numerically controlled equipment are presented. Economic feasibility issues and work safety aspects of automated road construction and maintenance equipment are outlined. The paper concludes that road construction and maintenance tasks have a significant potential for gradual automation due to the repetitiveness and relatively moderate sensory requirements of many tasks. Ultimately, integrated, multitask systems should be feasible once single‐purpose automated equipment proves successful.

The problems experienced with periodic and sometimes mandatory cleaning of the undersides of light‐rail commuter railcars are common to transit authorities throughout North America. The predominant causes for concern are the level of cleaning and, more importantly, the effects of airborne contaminants on the personnel in the vicinity of the air blowdown operation. Recognizing the need to improve both conditions and performance, the Toronto Transit Commission (TTC) and the Ministry of Transportation of Ontario (MTO) undertook a detailed study designed to evaluate the feasibility of using industrial robots to perform the task. Working in conjunction with Vadeko International Inc., a Toronto‐area engineering company specializing in robotics for hazardous environments, the study established that a robotic system would greatly improve both the working conditions and the quality of cleaning with substantial long‐term financial benefits following a relatively short payback period. Robotics development is at a stage now that would permit the automation of many transit‐vehicle maintenance and servicing tasks. Several robotics applications are in the planning and testing stages or are being implemented by some transit authorities.

An automatic pavement‐distress‐survey system that uses laser, video, and image processing techniques has recently been developed. This system consists of a survey vehicle and a data‐processing system. The survey vehicle can measure cracking, rutting, and longitudinal profile simultaneously, without contact, rapidly and accurately. The data‐processing system can convert the measured data automatically into formats that can be used in the pavement data bank. As for cracking, cracks over 1 mm wide can be measured, and it is easy to output the various parameters calculated from length, width, direction, position and number of cracks. The cracking processor uses a unique line‐finding algorithm that can extract a crack in a noisy road image by analysis of projection curves. This algorithm is implemented in special‐purpose high‐speed hardware. In this hardware, up to 512 32‐bit microprocessors execute in parallel. This system allows automatic crack recognition that has conventionally only been performed by humans.

The potential application of image‐processing methods to automate the manual data collection and visual rating of pavement surface conditions has not been widely recognized until relatively recently. A cost‐effective automated system to capture and extract pavement‐surface distress from video images would improve safety and efficiency, and could offer consistency and uniformity of data and data quality, both locally and nationally. The purpose of this paper is to provide an introduction for transportation engineers, especially pavement engineers, to digital image‐processing concepts and applications in pavement management. This includes pavement‐surface‐distress data of concern, basic machine‐vision and digital‐image‐processing concepts, video‐system characteristics for automated distress‐data collection, and existing systems for digital imaging in pavement management in the United States, Japan, and France. It is concluded that in a relatively short time substantial progress has been made in the development of automated systems for distress‐data acquisition and interpretation, and enhanced capabilities can be expected in the near future. Digital imaging technology is playing a significant role in these efforts.

New technology and equipment are constantly sought by traffic engineers for dealing with the problem of urban congestion. Among the most promising concepts available today is the use of video imaging for vehicle detection, automatic surveillance, and extraction of data needed for developing advanced control concepts. In this paper, a recently developed video detection system is presented. The system operates in real time, it can detect traffic simultaneously at multiple points within the field of the camera's view, and it emulates loop detectors, i.e. it produces signals compatible with loops. The system was installed and tested both off‐line and in real time using taped data and field installations, respectively. The results up to this point suggest accuracy levels comparable to loops; higher accuracies than loops in speed measurements are expected. Finally, software is being developed for real‐time extraction of traffic parameters, state variables (i.e., queue lengths and size), and measures of effectiveness (delays, stops, energy consumption, etc.) by the device.

The advent of geographic information systems (GIS) has created a technology with considerable potential for achieving dramatic gains in efficiency and productivity for a multitude of traditional and innovative highway management applications. However, to capitalize on GIS technology, it will be necessary for highway agencies to adapt the way in which they collect, store, and utilize data, as well as undergo fundamental changes in how they carry out technical responsibilities. This paper addresses these considerations through a study of: (1) Highway management applications that can benefit from adaptation to GIS; (2) key GIS concepts affecting highway transportation; and (3) issues affecting GIS design and implementation within and between highway agencies. The results of this study are reported in terms of establishing guidelines for successfully achieving full GIS adaptation to highway management.

The emission inventory process at commercial airports can be a time‐consuming, error‐prone, involved process. Multiple sources of varying types also complicate the process. The writers have combined all source calculations in a series of spreadsheet templates, contained in a single file. Through the use of spreadsheet functions, such as macrocommands, the user answers questions from user‐friendly screen prompts, and emission quantities are shown in summary tables for each source and each pollutant as well as an overall summary table. Report tables and graphics are easily and quickly generated. As a result of using the spreadsheet method, various scenarios can be calculated in a matter of minutes and errors in calculations are avoided. This permits review of many alternatives, and is not only a tool for emission inventory compilation but is a planning tool as well.

This paper describes an expert system that helps the construction or highway engineer choose the most appropriate compactor under a set of job conditions. Selecting the suitable compactor is affected by numerous field variables. Most of the time, the construction engineer uses his or her experience and intuition to choose a compactor. Expert systems are well suited for formulating and organizing this type of experience‐based knowledge. The system developed in this research takes into consideration the degree of compaction required, job size, soil type, plasticity, moisture conditions, and breakage of aggregates. Recommendations made by the expert system apply to jobs specified to standard AASHTO densities. The system can be used as a tutorial tool for inexperienced personnel. Guidelines have been provided for future work and development of a data base of compactor information.

When concrete pavement is subjected to a change in temperature, some time must elapse before a condition of equilibrium is again reached. In the transient heating and cooling processes that take place in the interim, there are three basic energy transfer modes: (1) Radiant; (2) convective; and (3) conductive heat transfer. As a concrete pavement's thermal environment changes, the physical mechanisms that underlie the heat‐transfer modes cause fluctuating temporal zones to occur within the pavement slab. For instance, during a freeze‐thaw cycle the upper portion of the pavement may be subject to thawing and refreezing while the bottom portion of the slab remains frozen. By using a finite‐difference computer model coupled with field and laboratory observations, the writers discuss how the rate and depth of temperature change can be accurately predicted. Freeze‐thaw cycles in which surface scaling occurred are used to illustrate one of the different kinds of exposure conditions that can be accurately simulated.

The present research was aimed at development of a low‐maintenance crash cushion utilizing reusable rubber elements. Energy dissipation characteristics of full‐scale hollow circular rubber cylinders was investigated through static and dynamic testing. Effects of clustering cylindrical elements on energy dissipation was also examined through dynamic testing. A full‐scale prototype crash cushion was constructed from a cluster of rubber cylinders formed from a natural rubber (NR) product containing a 20% ethylene‐propylene‐diene monomer (EPDM) blend and subjected to a series of vehicular crash tests. Although unexpected failures in the rubber cylinders prevented acceptance of the prototype cushion in terms of recommended impact performance criteria, the failures were attributed to a mandrel‐wrapping process for which a compression‐mold process can be substituted. A low‐maintenance rubber crash cushion is technically and economically feasible and can reduce life‐cycle costs by 60% or more at high‐accident locations. Further development is therefore recommended.

This paper is a result of a research project conducted in a Floridian county transit for one year. The primary objective of the paper is to present the study of the impact of automation on “total productivity” in bus transit. This was accomplished by first developing and applying a methodology for measuring the total productivity of the transit facility and then using the Total Productivity Model (TPM) and statistical techniques to measure the impact of automation on total productivity over a period of time. This paper bears a significant value to a transit manager, in that the methodology presented here can be applied to prospective technologies before they are acquired.

Function subprograms are provided for the solution of the AASHTO equations for both flexible and rigid pavement design using the well known Newton-Raphson root finding numerical solution technique. The code was written for the Microsoft® version 4.1 FORTRAN optimizing compiler for microcomputers. The subprograms use equations from both volumes of the 1986 AASHTO Guide for Design of Pavement Structures. The programs promote effective use of the equations, especially in the material and structural design of base and subbase courses.