TAILGATE TALK – Vertical Clearance Checks

Did you roll out of bed this morning with vertical clearances being the first thing on your mind? Probably not…

Today’s Tailgate Talk is a simple reminder:

LOOK UP: Are you going to be high enough?

How many elements on your jobsite require vehicular clearance to be maintained? Of course, there are obvious elements like bridge beams, but are you remembering about some of the other elements?

It seems obvious as you are now reading this, but prior to you reading this article, when was the last time that you remembered about the need to check it? You’re not alone, it happens to us all.

REMINDER: Think about what job elements you have with clearance constraints:

–Overhead sign structures (truss-mounts & cantilevers)

–Bridge mounted signs/walkway platforms

–Cable spans

–Traffic signal heads

TIP: Pavement resurfacing or reconstruction usually changes the finished grade elevations under things: Are you milling & overlaying? Don’t take it for granted – Check your finished pavement relative to what’s above it. Don’t assume the designer did it – Check it.

The sketches I’ve incorporated into this post were checks of a couple of cantilever signs that we installed on IL-171 last season. Not only were the signs new, but we changed the paving profile. Spend some time (as I have done here) checking all of your proposed pavement elevations relative to the sign post. I’ve included a LINK HERE if you’d like to take a look at how I set my calculations up.

TIP: Check your sign foundation elevations to see how they match with the actual pavement elevations.

Design engineers do not always get these calculations right – Want proof? It happened to us during the widening of I-55 in Plainfield in 2008. Fortunately for us, I caught it: Running calculation checks like the example I’ve given found that the designers used an incorrect shoulder pavement elevation to determine the foundation elevation. We had the ability to adjust the top of foundation elevation and circumnavigate what would have been a major problem had the sign been installed using the design drawings.

EXAMPLE: Here’s what happens when you don’t check your foundation heights – See that spool section at the bottom of the cantilever sign post? That looks like a retrofit to me. Something tells me that the designer never checked to see how the pavement & ditch grades sync’d and simply designed the foundation based on the pavement….

I say it all the time: Check, check & check. Take nothing for granted on your projects. Be the Commander. Task to understand all facets of your jobsite. Spend time dirt diving the details. Simple elevation checks like these can pay huge dividends if you can overt a fabrication/installation issue before it occurs.

WRAP UP: Your Tailgate Talk assignment for today is simple: Look up.

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