This webinar is co-sponsored by ASCE's Transportation and Development Institute and ASCE Continuing Education

Purpose and Background

Low-volume roads make up 60 to 70 percent of all roads worldwide. In the United States there are over 2.5 million miles of low-volume roads. On those roads, major investments are made in the materials used for surfacing and in drainage crossing structures such as culverts, fords, and bridges. Thus understanding the many aspects of roadway drainage is important to achieve good designs, to protect our investment in the roads, to minimize damage and maintenance needs, and to protect water quality near the road and at crossings.

As the old saying goes, three of the most important aspects of road design are Drainage, Drainage, and Drainage! This webinar will address those aspects. Many road surface drainage techniques exist to keep water off the road surface and to avoid concentration of water. These include maintaining a good crown on the road, or establishing an in-sloped or out-sloped profile. Frequent culvert cross drains, rolling dips, lead-off ditches, drop inlets, and other measures help avoid excessive water accumulation and associated damage.

Most road systems have hundreds to thousands of culverts, many very old, and many that have failed and have been replaced at some time. Proper culvert sizing is critical, along with proper installation, alignment, bedding and compaction, use of headwalls and end sections, etc. They may need protection against plugging or the damage from overtopping or bank erosion. Properly designed low-water crossings can offer a cost-effective alternative to culverts in some circumstances, especially on low-volume roads. Finally, bridges are a huge investment and are key structures to keep roads open. Maintaining adequate hydraulic capacity and protection against a variety of scour problems (the most common cause of bridge failure) are critical. Other key bridge issues are channel debris, approach stream-bank stabilization, and changes in the channel, all of which can be mitigated.

Learning Outcomes

You will learn the importance of drainage on roads, both on the road surface, and at each location where the road crosses a drainage channel. In addition, you will learn what is important to make a culvert and bridge function properly and how to achieve their design lives. Emphasis will be placed on avoiding the problems that cause structural failures, including inadequate structure hydraulic capacity, poor installation, plugging problems, and scour.

Webinar Benefits

• Understand the importance of keeping water off the road surface
• Learn how to properly avoid water concentration and to drain the road
• Understand the most important issues in culvert design and installation
• Prevent culvert failures, particularly plugging
• Learn how to design and properly use low-water crossings
• Understand what is most important in designing and protecting a bridge, particularly against scour

Intended Audience

Professionals involved in the planning, design, maintenance, repair and management of low-volume roads and their drainage crossing structures will benefit from this webinar, especially:

• Civil engineers
• Road managers and maintenance personnel
• Field technicians and hydrologists 

 Webinar Outline

• Introduction to low-volume road drainage issues
• Roadway surface drainage measures
• Key culvert design and installation factors
• Techniques to avoid culvert failures and damage
• Use and design of fords and low-water crossings
• Key bridge location, design, and maintenance issues