In a previous post I discussed the benefits of using a three-dimensional design model for civil engineering projects. And I’m not referring to sitting in an IMAX theatre with dorky, oversized plastic glasses (wait…those are coming back in style, aren’t they…) ducking my head as a 4-story movie screen zooms me through a newly designed streetscape. What I’m referring to is the much, MUCH more exhilarating practice of assigning not just length and width to, say, an underground stormpipe, but also a depth (!) under the surface of the road.
The world isn’t flat anymore
Compare this to 10 or even 5 years ago when I would just draw a “flat” line representing a new storm pipe….now we can also assign an elevation to each end of the pipe and be able to compare it to the road elevation and the elevation of other utilities. We’re also able to view it from multiple perspectives that are all linked to the virtual characteristics assigned to that virtual pipe. We can do this not just with pipes, but earthwork, streets, sidewalks, and curbing. This is why I find that I’ll use three-dimensional modeling for at least one aspect of most of my projects. I’m by no means an expert in this, but I’ll just give you an example of how I’ve found it extremely helpful for me.
The butterfly effect
Let’s take street design again…in my opinion, reconstructing an existing street within a 250 year old borough is about a one MILLION times more difficult than plopping a brand new street into an open field. Street reconstructions require us to consider every single set of steps leading up to a front door, every single water and sewer vent, every single window well, every single shrub, every single mailbox and every single sidewalk connection that currently exists. For an average street block that’s on the order of magnitude of one MILLION tiny (but extremely important) inter-related bits of info that need to be analyzed and considered in the design. Then we need to make sure our sidewalks are sloped enough (but not too much), the top of the curb doesn’t look like a roller coaster and the road cross section is within tolerances. Throw in a steep, San Francisco-like street slope and a few 150 year old utilities and it’s a recipe for small scale engineering chaos.
Revisionist history at its best
Thankfully a three-dimensional model allows those points to be analyzed much more easily and the design constraints to be much more visible. We can now view most of those variables in one screen shot and check to make sure all are accounted for as best as we can. I can place slope labels every 20 feet on my sidewalk to make sure I’m within ADA regulations. I can compare the edge of my sidewalk to the bottom of every front door stoop to see how they tie in. Instead of the laborious and time-consuming trial and error process that a two-dimensional design approach required, we can efficiently revise each element of the new design to match the existing conditions as best as we can. As you can imagine, it is usually pretty challenging to try to satisfy ALL of those requirements and trade-offs often have to be made. I think it was Abraham Lincoln who wisely once said: You can match all of the front stoops some of the time, or some of them all of the time, but…well…you know.
A 3D community
This hasn’t made me into the perfect designer. I still miss some things. But this approach has made it easier and quicker for me to make design revisions. And it has greatly increased my chances of catching a design inconsistency BEFORE a shovel hits the ground. If the contractor builds in 3D…and a homeowner experiences the improvements in 3D…it only makes sense for the engineer to design in 3D. With or without glasses.