Heavy highway. It is the only type of project I have ever heard of someone refusing to build data for. It is by far the most common type of project that we are called upon to rebuild after someone failed in their attempt to build it. And it still makes my stomach hurt when I hear about someone building data for a heavy highway project based on contours only. It represents our biggest projects, from our biggest clients. Heavy highway projects from the past years represent both the most difficult and most time consuming undertakings from our company. And let us not forget that an engineering firm (or firms) spent years putting together this design that you have days to recreate. Perfectly. Alone. While there are certainly exceptions in the form of some real oddball projects, I see heavy highway as the height of both transportation engineering design and data building.

But, should heavy highways be really that difficult to build?

An interesting object lesson from my schooling was learning about the design and construction of the first series of space shuttles. Instead of one team tackling the entire design, individual components were given to separate teams and/or contractors. In the end, all the individual components were then designed into one whole: the shuttle itself. This has become standard operating procedure for many forms of design, and I feel that highway design plays best by the same rules. If taken as a whole, highway design can be downright impossible. If broken down into distinct and separate components, highway design becomes a much more straightforward affair. My objective over the next couple of articles is going to be to do just that. Over the last dozen or so years I have built my fair share of roadway and highway projects as both an engineer and data builder. I have learned the hard way the right and wrong way to work with highways. As would be obvious, this learning process is still going strong. Design steps that I thought were critical even last year have been refined, replaced or rejected altogether.

So what do I consider a heavy highway? My personal definition from a data builder perspective would define a heavy highway as a multilane roadway defined by plan, profile, typical section, cross section, intersection and super elevation information. Proposed grade contours or spot elevations (outside of intersections) are usually not included. In other words, for your work to be accurate and complete you *must* build the project off of the above mentioned information. In almost every case there are no contours to act as a crutch to lazy and/or incorrect data building procedures and techniques. There is no alternative or trick to work around building this roadway as a roadway in the software of your choice.

Before I start, I need to get some assumptions and clarifications out of the way. While there are similarities between the major design software's (AutoCAD, Terramodel, Carlson and Microstation), each one is certainly unique in its own way. I have always, used Terramodel as my design software for a number of reasons. As such, my general steps and procedures are required by Terramodel. Some adjustments may obviously need to be made to make my procedure apply to the software of your choice. In other words, some extra steps may be needed to build a road in AutoCAD, or fewer steps may be needed to built that same road in Microstation. Also, each highway project is unique. Entire portions of design that *should* have been included in the engineers design may be missing. For example, many roadways do not have intersection details. Adjustments will obviously be necessary in these cases.

This article is intended as the introduction to the next five articles on heavy highway design. Following is a brief introduction to the next five articles covering heavy highway data building:

1. PLAN - This phase consists of establishing firm horizontal alignments (HAL's) for all proposed roadways, ramps and critical edge of pavement lines. This includes determining the station ranges of construction for the major roadway segments.
2. PROFILE - Next, for each major roadway we must associate detailed vertical alignments (VAL's or profile's) with each HAL. In addition, if available from the design, we will also need detailed super elevation transitions for each HAL. VAL's could be needed for additional features such as roadside ditches.
3. TYPICAL - The next major step is to determine the typical sections for the length of the major roadways. For most heavy highways, there are multiple typical sections for one roadway. Once the correct typical sections have been determined, they need to be entered into the software as templates associated with specific station ranges. The design may include moving edge's of pavement, shoulder and so on. These will need to be included into the templates as well.
4. SLAP DOWN - Once each roadway has been defined by a plan, profile and templates, it can be built into the program. For some programs, this will require specific XLINES and/or intervals for the proposed surface. Work will be needed to clip back unneeded or incorrect segments.
5. INTERSECTIONS and CONTOURS - Once all roadways are built, they need to be cleaned, joined and clipped to be ready for a final model. This usually includes working with the projects intersection details (if they exist) and adding proposed grade contours outside the roadway. This is the final step of work.

By no means do I think my process is the end all, be all. However, it is my hope that the next five articles will help both those who are new to building heavy highways, and those who have done it for years. For those who are new to this process, I hope that it can serve as a starting point in their learning process. For the most experienced, I hope that it can at least shed some light on some of the finer points. Regardless, due to the general lack of any information available anywhere for specific procedures on building data, any procedure is better than none. Even mine. Well, hopefully :)

Read more of Chad's articles here.