The roughness prediction models in the International Roughness Index (IRI) currently incorporated into the Mechanistic-Empirical Pavement Design Guide (M-E PDG) have been developed by means of ordinary least squares (OLS). However, some of the variables used in predicting future IRI were previously estimated by means of separate performance models. This could cause bias because of the correlation between the previously estimated distress types and unobserved components on the IRI model. The bias can be corrected by considering additional variables that are correlated with the distress types causing the bias, thus eliminating the correlation to the unobserved terms in the model. Bias in the IRI model can also be generated by unobserved factors not included in the model. If these factors are section-specific, the bias can be removed considering variations in the performance history of different pavement sections. The writers have used updated Long-Term Pavement Performance (LTPP) data consistent with the data set originally used to fit the M-E IRI model for flexible pavements over thick granular bases contained in the M-E PDG. The data were then used in modeling IRI by means of OLS and instrumental variable (IV) regressions analyzing the data as pooled and as a panel data set (by random-effects, fixed-effects, and joint random-effects approach) to check for possible bias in the model. It was found that the current IRI model, as estimated by OLS, exhibits several types of biases attributed to heterogeneity and incorrect assumptions in the modeling process. It was identified that the preferred IRI model was the joint random-effects approach and, therefore, the model parameters were estimated by correcting the omitted-variable bias and simultaneous-equation bias. Estimating the model by accounting for possible bias in the data indicated considerable changes in the effects of different parameters affecting IRI through time, mainly rutting of the pavement structure.

Dynamic vehicle behavior is used to identify safe traffic speed limits. The proposed methodology is based on the vehicle vertical wheel contact force response excited by measured pavement irregularities on the frequency domain. A quarter-car model is used to identify vehicle dynamic behavior. The vertical elevation of an unpaved road surface has been measured. The roughness spectral density is quantified as ISO Level C. Calculations for the vehicle inertance function were derived by using the vertical contact force transfer function weighed by the pavement spectral density roughness function in the frequency domain. The statistical contact load variation is obtained from the vehicle inertance density function integration. The vehicle safety behavior concept is based on its handling ability properties. The ability to generate tangential forces on the wheel/road contact interface is the key to vehicle handling. This ability is related to tire/pavement contact forces. A contribution to establish a traffic safety speed limit is obtained from the likelihood of the loss of driveability. The results show that at speeds faster than $25\mathrm{km}/\mathrm{h}$ the likelihood of tire contact loss is possible when traveling on the measured road type.

Centerline rumble strips (CLRS) are patterns installed on the center of undivided, two-lane highways. Their main function is to alert drivers by producing noise and vibration. This treatment has been demonstrated to be effective in reducing crossover crashes. However, there are some disadvantages in their utilization, such as the exterior noise created by the strips. The objectives of this study were to quantify the levels of exterior noise; to verify the effects of speed, vehicle, CLRS shape, and distance on exterior noise; and to investigate the amount of noise created by CLRS that affects roadside residences and businesses. Two types of vehicles [2006 Ford Taurus (sedan) and 2008 Chevrolet Express (15 passenger van)] were driven over two different patterns of milled-in CLRS and over smooth asphalt pavement at two different speeds. Researchers collected the noise levels at three distances from the road at 10 different locations. Results indicated that vehicle type, speed, CLRS presence, and distance affect exterior noise levels. CLRS noise levels were statistically greater than smooth pavement noise levels, and the difference would be perceived by human ears at distances up to 45 meters.

The yards are facilities that reassemble inbound freight train cars into outbound freight trains. These facilities play an essential role for providing the freight transportation service by rail, however, they are nonrevenue producing elements for the railway freight companies and therefore keeping them unutilized is not acceptable. In this paper, a double-ended flat-shunted yard has been studied by discrete-event-based simulations. The results obtained demonstrate significantly low utilization levels of the subsystems of this yard. Therefore, a possible reduction of floating resources is investigated.

This paper presents a new Chinese Train Control System (CTCS), the CTCS-2I, for trains traveling up to $350\mathrm{km}/\mathrm{h}$. Building on the capabilities of CTCS-2, the CTCS-2I system provides safety control for trains traveling at $350\mathrm{km}/\mathrm{h}$ by increasing track-circuit information capacity, changing block section parameters, and adjusting other crucial settings. It solves some key issues of the CTCS-2I system operating on $300\mathrm{to}350\mathrm{km}/\mathrm{h}$ trains, including train-operation control information content and safe train-tracking intervals. The CTCS-2I offers a train-control system in addition to the European train-control system, ETCS-1; and CTCS-3, which both provide safety control for trains traveling at $350\mathrm{km}/\mathrm{h}$. Furthermore, the CTCS-2I overcomes the shortcomings of real time in the point-type ETCS-1 and averts complications in CTCS-3, including poor compatibility between CTCS-3 and CTCS-2, as well as the structural overcomplexity of CTCS-3 caused by incompatibility transmission in the track circuit and Global System for Mobile Communications–Railway (GSM-R). By contrast, the CTCS-2I system is characterized by its simple structure, good compatibility, low cost, and easy implementation. The necessity of creating a new kind of train-control system, CTCS-2I, has been proved through analysis of the potential problems found in both the CTCS-3 and CTCS-2. The components and working principles of CTCS-2I are detailed in this paper. The key control techniques for $300\mathrm{to}350\mathrm{km}/\mathrm{h}$ trains, such as information content, block section settings, compatibility, reliability, and safety, are also described. The performance and characteristics of the CTCS-2I are further compared with CTCS-2, ETCS-1, and CTCS-3.

Roadway designs intend to provide a safe facility addressing mobility concerns, accommodating the physical and social environment and within financial constraints. Sometimes, trade-offs among these may be needed to deliver the desired project and designers need tools to estimate the safety implications from such decisions. The work completed here aimed to develop a set of recommendations to be used in evaluating safety implications from design element trade-offs. The effort focused on developing crash-prediction models and accident modification factors (AMFs) for multilane rural roads regarding lane width, shoulder width, and median width and type. The available data limited these models to four-lane roadways with 12-ft lanes. Separate models were developed for divided and undivided facilities as well as for single-vehicle, multivehicle, and all crashes involving both total and injury crashes. The AMF values recommended here were compared to those proposed in the Highway Safety Manual. Most of the proposed values are in accordance with previous work and demonstrate the effect of these elements on crash occurrence.

Hurricanes are one of the most costly natural disasters in the United States and have increased in frequency in the last few years. The critical role of evacuation, particularly for the vulnerable communities, has been realized from some disastrous evacuation experiences in recent hurricanes (for example, Hurricanes Katrina and Rita in 2005). Therefore, a thorough understanding of the determinants of evacuation behavior is needed to protect the loss of lives, especially in the vulnerable communities. However, a household’s decision-making process under a hurricane risk is a very complex process influenced by many factors. This paper presents a model of household hurricane evacuation behavior accounting for households’ heterogeneous behavior in decision making by using original data from Hurricane Ivan. It develops a mixed logit (also known as random-parameters logit) model of hurricane evacuation decision, where random parameters reflect the heterogeneous responses of households caused by a hurricane. We report several factors consistent with some of the previous findings, which are important for understanding household-level evacuation decision making. We also explain the varied influences of some of the determining variables on the hurricane evacuation decision.

This paper presents a study that examines repair costs for different road barrier types and factors that influence these costs. The analyses focused on w-beam and cable barriers used as median barriers. To some extent, pipe barriers, Kohlswa-beam barriers, and concrete barriers were also studied. The influencing factors included in this study were road type, speed limit, barrier type, and seasonal effects. A case study was conducted in four regions of the Swedish Road Administration. Data were collected from 1,625 barrier repairs carried out during 2005 and 2006. The results show that the number of barrier repairs and the average repair cost per vehicle kilometer are higher along collision-free roads than along motorways and 4-lane roads. The results also show that the number of barrier repairs and the average repair cost per vehicle kilometer are higher for cable barrier than for other barrier types. No conclusion can be drawn regarding influence of speed limits on barrier repairs and associated costs as the result from the regions are divergent and not statistically significant.

This paper presents a mathematical model to determine both a worker’s decision to participate in a nonwork activity and the decision about whether to include it in the basic home–work–home commute. By using household travel survey data from Beijing, China, this paper presents an empirical analysis framework to examine commuters’ nonwork stop-making behavior in a highly urbanized environment in a developing country. To account for the censored nature of the decision about whether to include a nonwork stop in the commute tour, a bivariate probit selection model was used. To enhance the behavioral basis for the model, extensive statistical tests were performed on model specifications and assumptions. The empirical results provide useful insights into the effects of individual/household sociodemographics, transportation measures, work schedule, and mode choice on commuters’ nonwork stop-making propensity. This study also provides methodological evidence that could lead to an approach for predicting the changes in commuters’ nonwork stop-making behavior as a result of the changes in sociodemographics and transportation scenarios.