Dangers of Using Online Tools to Design

Dangers of Using Online Tools to Design

As civil engineers, there is no way that we can have a perfect set of plans.  Our plans can’t include every possible thing.  We are limited to the information that we have.  Survey crews can only shoot a limited number of points, field conditions may have changed without as-built plans being updated, mathematical models are based on assumptions, or any thing else can cause errors in design.
Because of that I encourage civil engineers to use all available resources to limit as many errors as possible.  Some of the great new resources that have come out in the past few years are online resources like satellite maps, Google Street View and Microsoft Bird’s Eye View.  They work well as aerial overlays on plan maps.  They can also be used to get a quick look at where a river runs or where certain features are in relation to everything else.
However, be careful, they are not updated in real time.  In many cases they aren’t updated more than every few years.  Many things can change in that time.  Be sure to verify important features with a field visit before changing your plans.
I learned this early on.  During my internship days I was working on traffic model.  I compared my traffic model to Google’s Street View.  Google’s Street View and aerial map had a traffic signal that my model didn’t.  Well, I updated my model to include that signal and redid the calculations to include that signal.  Fortunately the engineer that I worked for was more skeptical and sent me on a field visit.  Sure enough, the traffic signal had been removed.  I had wasted some time rebuilding the model, but I learned that there is no substitute for a field visit.
Since then I’ve seen many other examples of the same thing: walls put up since the survey was done, driveways added and removed, intersection geometry changed, gas lines installed, just to list a few.
The bottom line, these tools are great and can help in your designs, but there is no substitution for a field visit.  You should visit your site during both the design and construction phases of your projects whenever practical.