Impact of Changing Traffic Characteristics and Environmental Conditions on Flexible Pavements

Abstract

Although the trend for the next generation of pavement design methods is shifting to mechanistic design, the use of design methods based on the AASHO road test results is still the current design practice in Texas and some other states. Critical to these design methods are the AASHTO load equivalency factors (LEFs), which are used to convert the mixed traffic axle loads into standard 18-kip (80.1-kN) equivalent single-axle loads. Several studies have been conducted on the subject of load equivalency for pavement design and analysis. However, there remain uncertainties related to various issues of load equivalency. Over the years, the composition and characteristics of traffic using Texas highways have been changing. The North American Free Trade Agreement has accelerated such changes in that more trucks, primarily moving among mid-western states, Texas, and Mexico, are traveling on Texas highways. In addition, the original AASHO road test was conducted at a site with environmental conditions significantly different from the environmental conditions in Texas. It is therefore critical to understand fully the impact of such changing traffic characteristics and environmental conditions on pavements in Texas. Presented is the methodology used to analyze the impact of these factors on the AASHTO LEFs.

Highway-user fees for overweight trucks: Consequences of deviations from the fourth-power law

“…A number of researchers have argued that the AASHO LEFs are based on empirical models that are not valid outside the scope of the material, climatic conditions, and vehicle characteristics that existed at the time of the AASHO road test; the implication is that the consumption estimates that are based on the AASHO LEFs may be questionable and could result in inequity of the user fees derived from such consumption costs (Johnsson, 2004;Anani and Madanat, 2010). Also, the modern-day use of super-single tires, new suspension systems, new axle configurations, higher tire pressures, composite pavements, new pavement materials, and the availability of advanced statistical techniques or enhanced analysis of pavement condition data have raised further concerns about the validity and reliability of the AASHO LEFs as well as the potential for improving them (Zhang et al, 2000;Bruzelius, 2004).…”

“…The ESALs, or load equivalency factors (LEFs), determined using the fourth-power law express the relationship between the loading and pavement consumption on the basis of the present serviceability index (PSI), a specific measure of pavement condition. For developing the AASHO LEFs, the variables used are axle load, axle configuration (single, tandem), structural number for flexible pavements, slab thickness for rigid pavements, and terminal serviceability (Zhang et al, 2000). A number of researchers have argued that the AASHO LEFs are based on empirical models that are not valid outside the scope of the material, climatic conditions, and vehicle characteristics that existed at the time of the AASHO road test; the implication is that the consumption estimates that are based on the AASHO LEFs may be questionable and could result in inequity of the user fees derived from such consumption costs (Johnsson, 2004;Anani and Madanat, 2010).…”

Incorporating Dynamic Traffic Distribution into Pavement Maintenance Optimization Model

“…We classify vehicles into 13 groups using the classification method from Federal Highway Administration (FHWA), and axle loads of vehicles are divided into 10 groups as in Reference [35]. The upper level of budget every year is US$ 45,000.…”

Kelių tampriosios dangos konstrukcijų savybių įtaka jų viršutinio sluoksnio eksploataciniams rodikliams

“…De Solminihac et al (2003), Jongvon, Sandhyeok (2006), parodė, kad automobilių kelių dangos būklę ir funkcionavimo trukmę apibūdinantys svarbiausi rodikliai yra asfaltbetonio atsparumas tempimui lenkiant ) (a l R , kelių dangos konstrukcijos sluoksnių tampros moduliai E ir asfaltbetonio atsparumas nuovargiui ) ( a (Petkevičius 2000;Petkevičius, Podagėlis 2000). Darbų (Hudson, Flanagen 1987;Arand 1991;Puodžiukas 2000;Zhang et al 2000;Sivilevičius, Petkevičius 2002;Petkevičius et al 2010) analizė parodė, 1. AUTOMOBILIŲ KELIŲ TAMPRIOSIOS DANGOS KONSTRUKCIJŲ … kad veikiančių kelių dangą veiksnių įtaka yra sudėtinga, nes vieni veiksniai turi įtakos kitiems veiksniams.…”