Canelon, Dario J.

A guide for evaluation of highway subsurface drainage needs and design of subsurface drainage systems for highways has been developed for application to Minnesota highways. The guide provides background information on the benefits of subsurface drainage, methods for evaluating the need for subsurface drainage at a given location, selection of the type of drainage system to use, design of the drainage system, guidelines on how to construct/install the subsurface drainage systems for roads, and guidance on the value of maintenance and how to maintain such drainage systems.

This project involved the evaluation of some configurations of pavement subsurface drainage systems, including the conventional edgedrain system, and two centerline configurations, at 2-foot and 4-foot depths. Testing of these configurations took place on a newly constructed eight-mile section of Nobles County CSAH 35 near Worthington. Drained roadway sections were 500 feet long for each drainage treatment. Each of the treatments was replicated six times, with the outflow for each replication outlet through a tipping-bucket flow monitoring system. The experimental design tested both the drain configuration and the effect of relative elevation of the roadway. Measurement of relative wetness of the pavement base and subgrade materials for each of the drainage treatments was conducted with a Geonics electromagnetic induction instrument (EM38). Data were collected from March 2006 until November 2008, with breaks during the winter periods. Statistical analyses were conducted to look for treatment effects, using both drained volumes as well as the EM38 measurements as measures of drain efficacy. Additional project work included a finite element analysis of the drainage configurations, EM38 evaluation of drainage effectiveness of an open-graded base construction for streets in the city of Worthington, and evaluation of the potential drain plugging effect of crushed concrete fill.

Highway infrastructure represents a substantial portion of the total impervious areas that generate runoff water. Because of long winters in congested areas that require frequent applications of de-icing materials, much of the runoff has the potential for affecting downstream water quality. However, storm water management techniques themselves have the potential for compromising the integrity of adjacent highways when they result in significant increases of water content in the soil beneath the roadway. Because of impacts and the costs associated with construction and maintenance, any storm water management system needs to be assessed before any decisions are made regarding new highway development or redevelopment. The authors consider Best Management Practices (BMPs) as they relate to the most commonly used storm water management approaches including dry ponds, wet ponds, infiltration trenches, infiltration basins, constructed wetlands, grassed swales, bioretention cells, sand filters and porous pavements. They provide a framework for considering cost of practices, negative impact on infrastructure, results from a BMP-related survey of highway design and maintenance professionals and cost-estimation formulas for each of the most commonly used storm water management approaches in urban Minnesota.

Highway infrastructure represents a substantial portion of the total impervious areas that generate runoff water. Because of long winters in congested areas that require frequent applications of de-icing materials, much of the runoff has the potential for affecting downstream water quality. However, storm water management techniques themselves have the potential for compromising the integrity of adjacent highways when they result in significant increases of water content in the soil beneath the roadway. Because of impacts and the costs associated with construction and maintenance, any storm water management system needs to be assessed before any decisions are made regarding new highway development or redevelopment. The authors consider Best Management Practices (BMPs) as they relate to the most commonly used storm water management approaches including dry ponds, wet ponds, infiltration trenches, infiltration basins, constructed wetlands, grassed swales, bioretention cells, sand filters and porous pavements. They provide a framework for considering cost of practices, negative impact on infrastructure, results from a BMP-related survey of highway design and maintenance professionals and cost-estimation formulas for each of the most commonly used storm water management approaches in urban Minnesota.