What are the Elements of Highway Design?

Department Manager Lisa Peterson explains the key elements of highway design in less than 90 seconds.

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Hi, I’m Lisa Peterson, the department manager of the highway engineering group at the Mount Laurel office of New Jersey. I’m here to do my Dewberry Explains on highway design. There’s a few key things that we need to know:

The classification of the road. Is it a freeway that’s the fast moving roadways? Is it a collector road that would move us from our local towns to a major highway? Or is it a local road that has our schools, police stations, and our homes located on it?

Where is it? Is it in a rural terrain or an urban terrain? Is it a nice open area or are we confined by preexisting buildings that we need to fit some of our features in?

The topography. Is it mountainous? Is it flat? What other things exist in the area? Any historical locations? Are there highways that we need to tie into? Are their railroads that we need to consider?

The traffic. Vehicles, bikes, and pedestrians—what are their volumes? What’s their level of service? Those are other considerations that will help us with our later design features.

Vehicle type. Are cars using it? Are trucks using it? Buses? Each of them move differently than the other and it’s important to know who’s the majority user of that roadway.

And lastly and very importantly is our speed. We have a posted speed that we should be abiding by and then there’s the design speed that us as the highway engineers we would do our design by.