During first practice session for the long awaited Las Vegas Grand Prix, my two loves of construction and racing came crashing together following catastrophic consequences for the latter.
Having worked as a pipe foreman in my past and currently as a estimator for a site servicing contractor in the Great White North, deciphering the particulars in this case are not much different than a typical motorsport fan recognizing an Formula 1 car from an IndyCar and vice versa. So let’s go.
The Ferrari SF-23 piloted by Carlos Sainz had a high-speed unintended collision with a valve box lid. Is it a manhole cover or a drain cover?
It’s a valve box lid although most people can better relate to a manhole or drain cover, the main point is he hit something that he shouldn’t have, the exact detail isn’t necessary.
Lay of the land
In order for those in urbanized areas to enjoy endless supply of potable “high quality H2O” and for fire protection to be available from fire hydrants, a network of watermain must exist below ground. The culprit in this case begins as a buried gate valve. Valves are critical to the management of water distribution. It is imperative that valves exist on water distribution watermains so they can be shutdown during emergencies, for maintenance purposes, and the ability to make simple future branch connections.
The gate valve is operated from the surface, in this case, the road. In order for that to happen, a valve box is installed. A typical valve box is cylindrical in shape and made up of 3 pieces. A base sitting over the gate valve, a bottom riser, and the upper riser and lid meeting flush with the surface. The valve box is independent of the gate valve so it can handle traffic loading without transferring the loads directly to the valve body.
Why wasn’t the lid welded down?
That’s because it was a locking version of the lid. Based on the photos available from various sources, that lid looks like an EJ USA 6800 Solid Penthead locking valve box cover for a 5-1/4″ valve box.
The locking mechanism is a horizontal bar connected to a vertical screw in the middle of the lid, the bar hangs below the lid. The lid is lowered by hand into the upper valve box where it sits within a recessed lip, a ridge exists approximately three inches below the top the upper valve box riser with two slits for the the horizontal bar to slide through, the bar must be rotated below the ridge, the lid then pulled up for resistance against the nut and the screw turned from the top to lock the lid to the valve box. Perhaps picture a radiator cap, or an old school fuel cap.
How did this incident happen if the lid was locked down?
There’s been reports stating the FIA have blamed the failure of the concrete for the incident but reading the words one by one it would appear what’s been said has been misunderstood. I believe their intention was to say that FP1 was stopped because of the concrete failure, and not that the crash was caused by the concrete failure. The concrete has “failed” because it had been chipped.
Photos circulating the web have shown a new water box lid was initially brought out for the repair, but the casting of the upper lid, where the lid sits was broken along with the adjacent concrete collar. It appears they decided to fill the valve box with asphalt instead, the upper valve box riser needs to be dug up and replaced anyways, so filling it with asphalt was a quick and practical fix.
The concrete collar that exists around the valve box is independent from the valve box. The concrete serves as a maintenance feature. Traffic loading has a tendency to push the valve boxes down, and sometimes even break them below the surface. The concrete serves to resist the top of the box from settlement. It also allows for a better transition from the flexible nature of asphalt pavement to the box with concrete serving as a great intermediate support system for the valve box.
It should also be noted that this valve box is located at Las Vegas Boulevard South and West Flamingo Road. Prior to the repaving of the circuit, the pavement was significantly rutted by traffic loads. Otherwise, the concrete collar serves no other purpose and is only required as a municipal type standard. The valve boxes in my municipality do not have concrete collars around them for example, it isn’t a requirement here.
Regardless what belief might exist, the simple fact is the ultimate failure is that the lid, which was supposed to be locked to the upper portion of the valve box, became disconnected. The upper valve box and lid in theory should be able to be locked together as one unit and thrown off a mountain, they should in theory stay locked together. Yet in this case, the valve box is still in the ground and therefore the lid should in theory still be locked to it.
I can’t wrap my head around the logic of how the concrete collar, being completely separate from the two locked mechanical units managed to unlock them, and separate them, as the FIA may or may not be insinuating, it doesn’t make any sense.
Therefore, it is impossible to overlook the plausible scenario that the water box lid was not sufficiently secured to the water box itself, as most of the evidence points this way.
Looking at the damage, the concrete, asphalt and valve box remain at even level at the surface. The damage to the concrete is reflected by the broken portion of the valve box. This would suggest a significant impact has taken place.
The lock is also bent the wrong way. Had the lock been secured, and the lid ripped from the valve box, the horizontal bar would have been bent down, towards the ground. Photos available of the lid shows one side of the horizontal bar is bent towards the surface indicating a significant impact from above while dislodged.
There is also no way for that lid to come out unless it was suctioned out from the sleeve it sits in. The lid itself has a 1-1/2″ skirt and in its normal sitting position rests approximately 1/8″ below the the top of the valve box.
Based on the videos available of the incident, it appears Carlos hit the lid, the impact os quite severe therefore it had likely already been dislodged, by another car ahead of Sainz, sitting above the grade of the pavement still somewhat within the sleeve of the valve box and Carlos, like Russell in Baku, was the unlucky first driver to find it.
End all doubt and pull test the lids, all lids. For example, in concrete rehabilitation work, sometimes dowels are added to existing concrete structures. In order to verify their proper installation, a pulling unit applies a tensile axial load, basically trying to pull the newly installed dowels back out, to assure adequate resistance.
The same concept could just as easily be applied using a test rig that pulls on covers at a force greater than that of the suction created by F1 cars