Kumares C. Sinha

ITS Impacts on Safety and Traffic Management: An Investigation of Secondary Crash Causes

Freeway service patrols, an increasingly popular choice in combating the effects of traffic incidents on freeway operations, have been known to reduce incident response and clearance time. This reduction can help alleviate the delay due to non-recurrent, incident related congestion, as well as lower the chance of secondary crashes. While much work has been done in the direction of identifying the benefits stemming from the delay savings by freeway patrols, little has been done to identify the potential savings from lowering the likelihood of secondary crash occurrence. Using a 5-year incident data base from the Borman Expressway, we develop logistic regression models to examine what primary crash characteristics are likely to influence the likelihood of a secondary crash. The findings suggest that clearance time, season, type of vehicle involved, and lateral location of the primary crash significantly influence the likelihood of secondary crash occurrence. Further, the 1995 potential benefit from secondar...

Annual average daily traffic prediction model for county roads

A traffic prediction model that incorporates relevant demographic variables for county roads was developed. Field traffic data were collected from 40 out of 92 counties in Indiana. The selection of a county was based on population, state highway mileage, per capita income, and the presence of interstate highways. Three to four automatic traffic counters were installed in each selected county. Most counters installed on the selected road sections were based on the standard 48-hour traffic counts. Then, the obtained average daily traffic was converted to annual average daily traffic by means of adjustment factors. Multiple regression analysis was conducted to develop the model. There were quantitative and qualitative predictor variables used in the model development. To validate the developed model, additional field traffic data were collected from eight randomly selected counties. The accuracy measures of the validation showed the high accuracy of the model. The statistical analyses also found that the independent variables employed in the model were statistically significant. The number of independent variables included in the model was kept to a minimum.

An Analysis of Cost Overruns and Time Delays of INDOT Projects

A commonality among state Departments of Transportation is the inability to complete projects on time and within budget. This project assessed the extent of the problem of cost overruns, time delays, and change orders associated with Indiana Department of Transportation (INDOT) construction projects, identified the reasons for such problems, and finally developed a set of recommendations aimed at their future reduction. For comparison purposes, data from other states were collected and studied using a questionnaire instrument. The analysis of the cost overrun, time delay and change order data was done using an array of statistical methods. The literature review and agency survey showed that time delays, cost overruns and change orders are generally due to factors such as design, unexpected site conditions, increases in project scope, weather conditions, and other project changes. The results of the agency survey showed that with regard to the problem of cost overruns, INDOT has an average rank compared to other states. Between 1996 and 2001, the overall rate for cost overrun amounts for INDOT projects was determined as 4.5%, and it was found that 55% of all INDOT contracts experienced cost overruns. It was determined that the average cost overrun amount and rate, as well as the contributory cost overrun factors differ by project type. The average cost overrun rates were as follows: bridge projects -- 8.1%, road construction -- 5.6%, road resurfacing -- 2.6%, traffic projects -- 5.6%, maintenance projects -- 7.5%. With regard to time delays, it was found that 12% of all INDOT contracts experience time delays, and the average delay per contract was 115 days. With regard to change orders, the study found that the dominant category of reasons for change orders is “errors and omissions”, a finding which is suggestive of possible shortcomings in current design practices The statistical analyses in the present study showed that the major factors of cost overruns, time delays, and change orders in Indiana are contract bid amount, difference between the winning bid and second bid, difference between the winning bid and the engineer’s estimate, project type and location by district. Besides helping to identify or confirm influential factors of cost overruns, time delay and change orders, the developed regression models may be used to estimate the extent of future cost overruns, time delay and change orders of any future project given its project characteristics and any available contract details. Such models can therefore be useful in long-term budgeting and needs assessment studies. Finally, the present study made recommendations for improving the management of projects and the administration of contracts in order to reduce cost overruns, time delays and change orders.

Cost Savings Analysis of Performance-Based Contracts for Highway Maintenance Operations

Highway agencies around the world are undergoing major changes in their traditional maintenance practices, including the privatization of entire sections of highway routine maintenance activities. Performance-based contracts (PBC) are an option in such privatizing efforts. This paper presents a methodology to estimate the likelihood and amount of cost savings associated with the application of PBC for highway maintenance operations. Using data on maintenance contracts from around the world, we develop models that can be used to compare several contracting methods and include variables such as contract duration, activity type, and contract size. We find that large projects with strong competition, long duration and extension periods, long outsourced road sections that incorporate crack sealing, pothole repair, illumination repair/maintenance, and mowing activities, favor outsourcing under PBC. Our methodology can be useful to transportation agencies for making decisions about the use of PBC and other methods of maintenance outsourcing at the preplanning phase.

Life Cycle Cost Analysis for INDOT Pavement Design Procedures

Given the aging of highway pavements, high traffic levels, and uncertainty of sustained preservation funding, there is a need for balanced decision-making tools such as Life Cycle Cost Analysis (LCCA) to ensure long-term and cost-effective pavement investments. With driving forces such as Intermodal Surface Transportation Efficiency Act of 1991 (ISTEA), the National Highway System (NHS) Act of 1995, and the Transportation Equity Act for the 21st Century (TEA-21), LCCA enables evaluation of overall long-term economic efficiency between competing alternative investments and consequently has important applications in pavement design and management. It has been shown in past research that more effective long-term pavement investment could be made at lower cost using LCCA. Current LCCA-based pavement design and preservation practice in Indiana could be further enhanced by due consideration of user costs. Also, the existing Federal Highway Administration (FHWA) LCCA software could be further enhanced for increased versatility, flexibility, and more specific applicability to the needs of Indiana, particularly with regard to treatment cost estimation and development of alternative feasible preservation strategies (rehabilitation and maintenance types and timings). The study documented/developed several sets of alternative pavement design and preservation strategies consistent with existing and foreseen Indiana practice. The preservation strategies were developed using two alternative criteria – trigger values (pavement condition thresholds) and predefined time intervals (based on treatment service lives) and are intended for further study before they can be used for practice. These strategies were developed on the basis of historical pavement management data, existing Indiana Department of Transportation (INDOT) Design Manual standards, and a survey of experts. The study also found that with a few enhancements, FHWA’s current LCCA methodology and software (RealCost) could be adapted for use by INDOT for purposes of decision support for pavement investments and proceeded to make such enhancements. The resulting software product (RealCost-Indiana) is more versatile, flexible and specific to Indiana practice. The enhancements made include a mechanism by which the user can estimate the agency cost of each pavement design or preservation activity on the basis of line items and their unit rates, and a set of menus showing default or user-defined strategies for pavement preservation. Other enhancements made to the software include improved graphics, enhanced reporting of analysis results, and capability to simultaneously carry out analysis for more than two pavement design and preservation alternatives. A User Manual was prepared to facilitate the use of the enhanced software, and a Technical Manual was prepared to provide for the user a theoretical basis for various concepts used in the software. The enhanced LCCA methodology and software are useful for (i) identifying alternative INDOT pavement designs, (ii) identifying or developing alternative strategies for pavement rehabilitation and maintenance for a given pavement design (iii) estimating the life-cycle agency and user costs associated with a given strategy, (iv) comparative evaluation of alternative pavement designs. The enhanced methodology and software are applicable to existing pavements in need of some rehabilitation treatment, and also for planned (new) pavements. Future enhancements to the LCCA methodology and software may include a way to duly penalize parsimonious preservation strategies that are presently not adequately penalized for their resulting inferior pavement condition over the life cycle.

The Effectiveness of Maintenance and Its Impact on Capital Expenditures

With ever increasing traffic loadings, highway pavement maintenance needs continue to outpace the availability of resources, and transportation agencies seek cost-effective maintenance practices. This study investigated the effectiveness of maintenance treatments in the short-term and the cost effectiveness of maintenance strategies over entire pavement life. The study also analyzed the relationships and trade-offs between maintenance and capital investments such as pavement rehabilitation, and the trade-offs between preventive and corrective maintenance. These analyses were carried out through a work sequence that included analyses of historical trends, literature review, and a questionnaire survey. The study found that there are significant benefits associated with maintenance treatments, and that such short-term impacts generally involve an increase in pavement condition or a decrease in the rate of deterioration. For most treatments, a greater benefit is generally obtained for a larger effort expended on the maintenance treatment, at a given level of pavement condition, up to a point. The study also found that if chosen appropriately, maintenance strategies could be cost-effective in the long run. The most cost effective strategy was determined for each pavement family. Finally, the study determined that trade-off relationships exist between intervals of capital investments on one hand, and maintenance, traffic loading, and weather on the other hand: up to a point, increasing maintenance leads to increased rehabilitation interval, while increasing traffic loads and weather severity leads to reduction in rehabilitation interval, albeit at different rates for each pavement family. Marginal effects models were used to determine the effect of unit changes in maintenance levels, traffic loading, and weather on changes in rehabilitation interval. This information is useful not only for pavement management, but also for policy analyses involving truck weights, and pavement repair needs assessment to reflect changing traffic and weather conditions in the long-term. The data for the study was supplied by the Indiana Department of Transportation.

ANALYSIS OF CRASH RATES AT INTERSTATE WORK ZONES IN INDIANA

The aging Interstate system in the United States requires extensive rehabilitation and maintenance, which results in the closure of a significant portion of the system each year to accommodate work zones. These work zones not only cause travel delay, they also create safety hazards. An analysis of crash rates at Interstate work zones in Indiana is presented. Crash rates in work zones were found to be higher than those on comparable highway sections without work zones. It is believed that lane closure strategies also may influence crash potential at work zones. An analysis of the relative safety effects of two commonly used lane closure strategies, partial lane closure and crossover, is presented.

A fuzzy mathematical approach for bridge condition evaluation

Abstract There are presently no established guidelines available for a bridge inspector to follow when assessing the significance of multiple deterioration factors on the bridge condition rating. As such, the evaluation of an existing bridge is based on a highly subjective and non-uniform procedure, and usually suffers from imprecision and personal bias. Hence, any attempt to find the optimal solution for bridge management based on such rating procedure can be misleading. However, with the development of a fuzzy mathematical approach, human subjectivity and imprecision can be included systematically in the decision making process.

Three-Stage Least-Squares Analysis of Time and Cost Overruns in Construction Contracts

Construction cost overrun and time overrun (delay) are a significant problem in highway-construction project delivery. Previous research studies have provided insight into the factors that affect overruns; however the findings may have been limited because they do not explicitly consider the simultaneous relationship between cost and time overruns. In this paper, we use data from Indiana highway projects to provide empirical evidence that a simultaneous relationship exists between cost and time overruns and that analysis of these two contractual outputs need to take due cognizance of such simultaneity. Using the three-stage least-squares technique, we identify a number of factors that significantly affect cost overrun and time overrun and we show how the effect of these variables vary by attributes such as project type and results of the bidding process. The models developed in this paper can help agencies enhance the estimation of the expected overruns of final cost and the delay in completion time for their planned projects.

Trade-Off Analysis for Multiobjective Optimization in Transportation Asset Management by Generating Pareto Frontiers Using Extreme Points Nondominated Sorting Genetic Algorithm II

Investment decision making in transportation asset management is typically characterized by a wide diversity of asset types for purposes of optimization at overall system level. To enhance investment analysis and decision making for these multiobjective problem types, the analysis of trade-offs associated with different performance measures can be illuminating and informative. This paper provides techniques for efficient trade-off analysis as part of multiobjective-optimization for transportation asset management. The multiobjective-optimization problem is first formulated by establishing the objectives expressed in terms of network-level performance measures underlying the analysis of trade-offs. Then, the Extreme Points Nondominated Sorting Genetic Algorithm II (NSGA II) technique, an improvement over traditional NSGA II, is applied to generate Pareto frontiers that illustrate the trade-offs. Using candidate projects from a varied range of asset types as a case study, the paper successfully conducts the trade-offs between performance objectives and cost, and then among the performance objectives. The paper also shows that Extreme Points NSGA II has a faster convergence speed and yields a distribution that is superior to the traditional NSGA II.