Prasad Buddhavarapu

Framework for Determining Load Equivalencies with DARWin-ME

This paper presents a methodology for use of mechanistic–empirical design procedures to determine load equivalencies for various axle configurations and loads with a focus on oversize and overweight vehicles. The study uses the DARWin-ME system for pavement analysis and computation of equivalent damage factors (EDFs). In the context of the study, the EDFs for a given axle load and configuration consist of two partial factors: the axle load factor and the group equivalency factor. The framework adopted in this study defines a given axle load and configuration equivalent to a reference axle load based on equivalent pavement responses that results in the same distress level. The EDFs for single, tandem, tridem, and quad axles were evaluated for a wide spectrum of varying loads, and three failure criteria were applied: rutting, fatigue cracking, and roughness. Except in the case of rutting, there was no evidence that EDFs are affected by the structural capacity of the pavement sections. For single axles, it was found that thicker pavement structures are less sensitive to traffic loads. For tandem, tridem, and quad axles, the relationship was nonmonotonic. For fatigue cracking, a linear relationship between the axle load factor and the number of axles per axle group was observed. Finally, for roughness, the EDFs showed no systematic trend for the different structural numbers.

A fully Bayesian before–after analysis of permeable friction course (PFC) pavement wet weather safety

Permeable friction course (PFC), a porous hot-mix asphalt, is typically applied to improve wet weather safety on high-speed roadways in Texas. In order to warrant expensive PFC construction, a statistical evaluation of its safety benefits is essential. Generally, the literature on the effectiveness of porous mixes in reducing wet-weather crashes is limited and often inconclusive. In this study, the safety effectiveness of PFC was evaluated using a fully Bayesian before-after safety analysis. First, two groups of road segments overlaid with PFC and non-PFC material were identified across Texas; the non-PFC or reference road segments selected were similar to their PFC counterparts in terms of site specific features. Second, a negative binomial data generating process was assumed to model the underlying distribution of crash counts of PFC and reference road segments to perform Bayesian inference on the safety effectiveness. A data-augmentation based computationally efficient algorithm was employed for a fully Bayesian estimation. The statistical analysis shows that PFC is not effective in reducing wet weather crashes. It should be noted that the findings of this study are in agreement with the existing literature, although these studies were not based on a fully Bayesian statistical analysis. Our study suggests that the safety effectiveness of PFC road surfaces, or any other safety infrastructure, largely relies on its interrelationship with the road user. The results suggest that the safety infrastructure must be properly used to reap the benefits of the substantial investments.

Evaluation of the Benefits of Diamond Grinding of a Continuously Reinforced Concrete Pavement

This paper discusses a study to evaluate the benefits on a continuously reinforced concrete pavement (CRCP) of diamond grinding used specifically for improving pavement functionality in surface macrotexture, skid resistance, roughness, and noise. The effectiveness of diamond grinding in improving those properties is calculated on the basis of in-field observations. The effect of three preexisting conditions (carpet drag, burlap drag, and transverse tining) on the effectiveness of diamond grinding is also evaluated. The results of the analysis indicate that diamond grinding improved the surface macrotexture by 0.6 mm and skid resistance by about 60%. The surface roughness of the diamond-ground sections was, on average, appreciably reduced, from 124 to 80 in./mi. An average overall reduction in noise level of 3.2 dB(A) was evident. A maximum reduction in the region of the noise frequencies (1,000 to 2,500 Hz) was observed, with a maximum noise reduction of 5.6 dB(A) at 1,600 Hz. The grinding operation produced a relatively uniform surface in relation to these properties despite the varying preexisting conditions across the CRCP.

Assessment of Using Inertial Profilers to Measure Ride Quality on Short Projects

The Texas Department of Transportation (DOT) ride standard specifies two devices for measuring ride quality on pavement projects: the 10-ft (3-m) straightedge and the inertial profiler. According to this specification, inertial profilers measure the ride quality on projects longer than 2,500 ft (762 m). The 10-ft straightedge must be used to survey roughness for projects of less than 2,500 ft. A study was conducted to identify the potential issues associated with the use of inertial profilers and the international roughness index (IRI) algorithm on short projects. A literature review was performed to collect required information about the inertial profiler operation and the IRI algorithm. A field experiment was conducted with an inertial profiler certified by the Texas DOT. The collected data were analyzed to investigate the effect of profiling speed and segment length. The results indicate that inertial profilers can be used to collect profile data on short segments of less than 2,500 ft, but the IRI algorithm should be used on projects longer than 528 ft (161 m), below which the variation between IRI results increases significantly.

Pay Factors Based on Observed Field-Performance Data

AbstractThe fundamental purpose of any construction specification is to ensure the expected long-term performance of the final product. A construction project that fails to meet the required quality level should always result in reduced payment to the contractor in order to recover the future costs that the highway agency will incur for additional maintenance. However, a superior-quality project must be rewarded based on actual savings to the agency that correspond with the improvement in performance due to higher construction quality. Performance-related specification (PRS) incorporates the economic implications associated with superior or inferior pavement construction practices. In general, earlier PRS development studies were based on performance data collected from either pilot pavement construction projects or models built based on experimental pavement sections. This study primarily focuses on constructing a pay adjustment framework utilizing field performance data and actual quality control measur...

RETRACTED: Accuracy and Precision Assessment of High-Speed Measurements of Pavement Surface Cracking

This paper presents an independent evaluation of the accuracy and precision of high-speed field measurements of pavement surface distresses taken by three different 3D systems that represent the state-of-the-practice of automated distress collection equipment. The analyzed distress data were collected from a field experiment that comprised twenty 550-ft test sections that included both flexible and rigid pavements. The high-speed measurements produced were compared to manual measurements taken statically by experienced raters. The paper also presents a qualitative comparison between the crack maps produced at highway speeds and digital crack maps collected statically by manual measurement of the cracks. In addition, before-and-after analyses were conducted to assess for the change in accuracy achieved after conducting a visual inspection, and manual corrections, of the automated measurements.

Performance Related Specifications Development of Hot Mix and Concrete Pavement Projects Using Field Data

Fundamental purpose any of construction specification is to ensure the expected longterm performance of the final product. Performance Related Specification (PRS) incorporates the economic implications associated with superior or inferior pavement construction practices since it translates to extended or reduced pavement service life. Generally, earlier PRS development studies were based on performance data collected from either pilot pavement construction projects or the models built based on experimental pavement sections such as MEPDG. This study primarily focuses on constructing PRS framework utilizing field performance data and actual quality control measurements obtained during road construction projects. Laboratory density of plantmix and placement density of compacted hot mix pavement and as-constructed ride quality of both hot mix and concrete pavements are identified as performance-sensitive parameters. A performance related pay adjustment scheme that is governed by these performance-sensitive quality control parameters is developed.