On most segments in a state highway system, annual average daily traffic (AADT) in the current year is estimated by applying an applicable growth factor to coverage count data obtained in an earlier year. The accuracy of AADT estimates could conceivably be improved by exploiting existing imagery of highway segments containing vehicles. When both earlier year coverage counts and a current year image containing traffic information are available, a weighted combination of both pieces of information is proposed for AADT estimation. The weights can be easily estimated from available information and data regularly collected by state departments of transportation. An empirical study was conducted using 122 highway segments to evaluate the improved accuracy in estimating AADT that would have resulted from using this weighted method with a single contemporary image for a 10-year period from 1994 and 2003. The accuracy was markedly improved and stable over a large range of important input values. The demonstrated improvements in accuracy and the ease of using this method with existing data are great enough that field testing should now be considered.

The Trans-Texas Corridor (TTC) projects a vision of 6,400 centerline km of new roadways and railways, intended to provide a faster, safer and more reliable means of transport for people and freight, while fostering economic growth of Texas’s rural regions. This work enhances and then applies a random-utility-based multiregional input–output model to assess project impacts on trade, production, and worker locations. Driven by foreign exports and domestic demands, the enhanced model endogenously generates monetary trade flows for 18 economic sectors across Texas’ 254 counties, equilibrating explicit labor and land markets, along with capacity-constrained networks. The model predicts a slight redistribution of economic activities, increasing the supremacy of counties located closer to export zones, and an 8% reduction in the traffic volumes on existing highways. It also suggests a greater diversification of economic activity/production and moderate changes in the distribution of wages, floorspace rents and population, following the production trends. These effects are most noticeable in counties traversed by the TTC, especially in those previously inadequately connected to the State’s transportation network.

Travel time estimation models, which rely on speed data provided from point detectors (usually inductive loops), have application in travel time prediction and network performance monitoring. Unfortunately there are limited, and at times counterintuitive, results in the literature about their performance. This paper focuses on the field evaluation of four speed-based travel time estimation models, namely, the instantaneous model, the time slice model, the dynamic time slice model, and the linear model. Those models are evaluated using data from two operational motorways in Melbourne, Australia. Travel time estimation errors are quantified against actual travel times measured using a timed number plate survey and time-stamped toll tag data. There was little difference in the travel time estimation error across the models and they were all found to underestimate actual travel times. Errors ranged from about 7% in the off peak up to 15% in the peak. Marginal improvements in model performance were achieved through careful selection of which detectors provide input for each section (upstream, downstream, or the average of those values) and by conversion of the inputs from time mean speed to an estimate of space mean speed.

The paper demonstrates some inherent limitations of the TRANSYT software with regard to calibration of the recursive platoon dispersion model and, more specifically, modification of the travel time factor. Subsequently, the paper develops a procedure that overcomes this limitation by adjusting the average link travel time to control the value of the travel time factor indirectly. Furthermore, the paper presents numerical examples that provide a preliminary investigation of different calibration procedures of the recursive relationship. Although the dataset used for this purpose was generated using the INTEGRATION microscopic traffic-simulation software, the procedures are general and intended for use with field data. The calibration procedure developed in this paper is demonstrated to produce the best results in terms of simplicity and accuracy.

The paper improves upon the Yu and Van Aerde calibration procedure of the TRANSYT-7F platoon dispersion model, particularly for time steps greater than 1 s in duration, and develops three generalized platoon dispersion models that explicitly account for the effect of the time step duration on traffic dispersion. The paper then validates these models utilizing two datasets: the first includes field data gathered in Montréal, while the second was generated using INTEGRATION microscopic traffic-simulation software. The results demonstrate that the predicted flow profile using the proposed platoon dispersion models provides a good fit to field-observed and simulated profiles, regardless of the modeling time step considered.

In this paper, the preliminary application of a new type of cement-based piezoelectric sensor developed recently for monitoring the traffic flows is proposed and investigated. The sensor was made by bonding between two cubes of hardened cement sand paste with a commercially available piezoelectric ceramic plate encapsulated by a new sealant developed especially for the sensor’s fabrication, and its property was tested by dynamic loadings including harmonic loading, random loading, and pulse loading. Two experiments were carried out to prove the feasibility and reliability of the sensor for monitoring the traffic flows including the person flow and the vehicle flow in the field of transportation. The tested results show that the sensors can correctly respond to the pulse loadings induced by walking person or passing vehicle and the responses of sensors were approximately direct proportional to the peak values of pulse loadings. A conclusion is given that there is a good potential for the cement-based piezoelectric sensor in the engineering application for monitoring traffic flows in the field of transportation.

One of the 12 instrumented sections of the Virginia Smart Road was used to compare measured vertical compressive stress and measured transverse horizontal strain under the hot-mix asphalt (HMA) layer induced by a 25.8 kN (5.8 kip) single tire and a 39.5 kN (8.9 kip) set of dual tires to those calculated using layered linear elastic theory. The pavement section is composed of 38 mm (1.5 in.) HMA wearing surface, 150 mm (6 in.) of HMA base mix, 75 mm (3 in.) of asphalt stabilized open graded drainage layer, 150 mm (6 in.) of cement stabilized aggregate layer, and 175 mm (7 in.) of unbound aggregate base. The subgrade is a fill material composed mainly of rocks. Measured stresses were obtained using pressure cells embedded in the pavement during construction. Horizontal transverse strain was measured using H-type strain gauges that were also embedded during construction. Temperature in the pavement layers was measured using embedded T-type thermocouples. Theoretically calculated stresses and strains were obtained using software based on the layered-elastic theory (Kenpave, Bisar 3.0, Elsym5, and Everstress 5.0). In addition, two finite-element approaches were used. Results indicated that the layered elastic theory overestimates pavement responses at low and intermediate temperatures, but significantly underestimates the pavement responses to vehicular loading at high temperatures.

This paper defined a complete set of imaging based indices for different levels of coarse aggregate morphologies, i.e., the flat and elongated (FE) ratio, angularity index (AI), and surface texture (ST) index, and investigated their effects on permanent deformation behavior of hot mix asphalt (HMA). Image analyzed coarse aggregates were used to prepare eighteen Superpave HMA specimens using job mix formulas from ten State highway agencies and tested for permanent deformation at a specified high temperature. The permanent deformation data when linked to the morphological indices of the coarse aggregate, showed the best correlations with the ST index. The FE ratio demonstrated no measurable effects on the permanent deformation due to low percentage of flat and elongated particles used in the mixes. The influences of the AI and ST indices on the permanent deformation were especially significant when differences in the asphalt mix aggregate gradations were properly considered. A possible mechanism of coarse aggregate morphology affecting the stability and permanent deformation behavior of HMA was proposed in terms of particle geometrical interference in HMA.

The existing Det Norske Veritas (DNV) Recommended Practice RP E305 for pipeline on-bottom stability is mainly based on the pipe–soil interaction model reported by Wagner et al. in 1987, and the wake model reported by Lambrakos et al. in 1987, to calculate the soil resistance and the hydrodynamic forces upon pipeline, respectively. Unlike the methods in the DNV Practice, in this paper, an improved analysis method is proposed for the on-bottom stability of a submarine pipeline, which is based on the relationships between $U_m∕{\left(gD\right)}^{0.5}$ and $W_s∕\left(\gamma D^2\right)$ for various restraint conditions obtained by the hydrodynamic loading experiments, taking into account the coupling effects between wave, pipeline, and sandy seabed. The analysis procedure is illustrated with a detailed flow chart. A comparison is made between the submerged weights of pipeline predicted with the DNV Practice and those with the new method. The proposed analysis method may provide a helpful tool for the engineering practice of pipeline on-bottom stability design.

Location of the outer wheel path is an important input in the measurement of deflection response of a pavement and its riding quality. In the simulation of mixed traffic flow, it is also required to assign the position of a vehicle within a lane when it enters the test section. The statistical distributions fitted through the placement data recorded on 19 different sections of two-lane highways in India indicate that the placement of vehicles may follow a unimodal or a bimodal curve depending upon the percentage of slow and fast moving vehicles. Two parameters are introduced in this technical note. These are placement factor (PF) and skewness range (SR). It is observed that the placement data follow a unimodal curve if PF and SR are less than 1.3 and 0.54, respectively. Otherwise it is a case of bimodality.