Impact of Annual Average Daily Traffic on Highway Runoff Pollutant Concentrations

Abstract

The objective of this study was to evaluate correlations between annual average daily traffic (AADT) and storm water runoff pollutant concentrations generated from California Department of Transportation (Caltrans) highway sites. Analyses of data collected from the Caltrans Cyear (1997-01) highway runoff characterization program revealed that, in general, pollutant concentrations from urban highways were higher than those found from non-urban highways. For a limited number of pollutants, however, the concentrations from norrurban highways were found to be higher than the concentrations from urban highways. No direct linear correlation was found between highway runoff pollutant event mean concentrations (EMCs) and AADT. However, through multiple regression analyses, it was shown that AADT has an influence on most highway runoff constituent concentrations, in conjunction with factors associated with watershed characteristics and pollutant build-up and wash oft The other noticeable factors shown ' (530) 7537030, e-mail: claua@lrr~a.corn to influence the accumulation of pollutants on highways were antecedent dry period, drainage area, maximum rain intensity, and land use.Keywords: Annual average daily traffic (AADT), highway runoff, linear regression model, multiple regression model, and pollutants.The California Department of Transportation (Caltrans) is engagd in a multi-year program of research and monitoring pertaining to the environmental effects of stormwater quality from transportation facilities. Part of Caltrans storm water quality research and monitoring program involves the characterization of highway runoff (Kayhanian et al., 2001). These monitoring studies were principally undertaken (i) to comply with the statewide National Pollution Discharge Elimination System (NPDES) storm water permit requirements, (ii) to address legal requirements, (iii) to aid in developing new treatment systems, (iv) to develop runoff load models, and (v) to fill data gaps in stormwater runoff characterization for statistical analysis. The information presented in this paper is based on a 4-year highway stormwater runoff characterization study that was undertaken during the 1997-01 rainy seasons from October through April.Caltrans monitoring data are analyzed on a regular basis to assess runoff characteristics. One question that is frequently asked i s whether a correlation exists between annual average daily traffic (AADT) and the concentrations of highway runoff pollutants. The current paper addresses this issue. METHODS Sampling ProceduresRepresentative highway sites and storm events were selected for event-based monitoring. There are a wide range of parameters that can potentially affect the quality of stormwater discharges including geographic location, climatic/ecologic conditions, hydrologic conditions, land use, and AADT. The highway sites were selected to represent the full range of physical parameters. In addition, the sites were selected as potential monitoring sites based on the ability of the sampling t...

Controlling Stormwater Quality with Filter Soil—Event and Dry Weather Testing

“…The EC measured in the influent water is comparable to other studies [30][31][32] and was seen to increase from influent to percolate, reflecting that the water mobilized various ions as it passed through the soil.…”

“…The observed concentration of less than 50 mg/L of SS in the influent from both Odense and Copenhagen (Table 7) is relatively low compared to other studies [30][31][32], but was most likely due to the low traffic level in the areas. In the swale-trench systems in Odense the SS measured in the percolate is half of what is observed in the influent.…”

“…The observed influent concentrations at monitored sites in Odense and Copenhagen (Table 7) were generally low when compared with other studies [30,31,34]. Worth mentioning is that many organic contaminants such as pesticides, which proved to be problematic when added synthetically, were not included in the monitoring of rain events.…”

Quality and seasonal variation of rainwater harvested from concrete, asphalt, ceramic tile and green roofs in Chongqing, China

“…These results are consistent with those obtained by Fewtrell and Kay (2007) who observed that ADWP can markedly affect the quality of runoff water. Kayhanian et al (2003) used multiple linear regression analysis on data collected in California to find a statistically significant effect of ADWP on runoff concentrations for 25 of the 33 constituents tested. Twenty-three of the significant regressions had a positive coefficient (i.e., concentrations increase with longer ADWPs) with only two (pH and diazinon) showing a negative value.…”

Two-dimensional numerical simulation of groundwater contamination in the highway environment

“…The values obtained by Kayhanian et al (2003) have been taken as typical and their maximum values were selected as the basis of the input values for the simulations reported in this paper because they appear to represent 'worst-case' input contaminant loadings. Leachate concentration values were obtained from an earlier study by Hill (2004) who tested a wide range of conventional and alternative aggregates that might be used as base course materials.…”