Conrete highways vs. asphalt -- Why the difference in handling?

[ColoradoGuy]

My 2006 Toyota Tacoma is fitted with a new Eagle shell. We picked up our camper last June, and have put about 40 nights in it so far. My wife and I graduated to the camper after 35 years of tent camping. Couldn't be happier with our choice.

However, I noticed immediately that my truck handles differently on concrete highways. On asphalt, the ride is smooth as can be. On concrete, I get a herky-jerky ride that's very noticeable. Anyone else have this experience, or have an explanation? Thanks

Paul

 

[Sam]

If you mean a "bucking" sensation then I think the reason is that the concrete is poured in sections and each section is not exactly the same as the next so you end up with the rocking/bucking. Some vehicles do this worse than others and I think it's due to the length of the vehicle in relation to the length of the concrete sections.

I just pulled this theory out of thin air, so I hope there is a highway engineer on the forum that can set us straight

 

[chnlisle]

I agree and have noticed the same. For the most part asphalt is a monolithic "pour". The expansion joints in the concrete do just that and those giant commercial vehicles crack the joints as well. Just my opinion though.

 

[Stan@FourWheel]

maybe give P. Pevey a few minutes

he will probably check the forum on his lunch break

I bet he will probaby have some info for you on this topic



.

 

[DLN]

CG,

My Tacoma had the same problem before adding heavier shocks and air bags, now the ride is much better, no bucking over the expansion joints.
I'm not a highway engineer buy did study road design along the way. Sam and Jay are correct concerning the expansion joints. Heavy vehicles tend to degrade the joints and cause the individual slabs to rock slightly creating a dip or step at the slab ends.

 

[ColoradoGuy]

Bucking

Yeah, "bucking" is a good way to describe it. Usually this occurs at highway speeds at or above 40 mph. What's odd is that it doesn't always occur on concrete. Just sometimes. Anyway, I'm glad to see that others have noticed it too.

Stan, do you recommend purchasing heavy-duty shocks? Don't know how that would affect the warranty, but I'll do it if it's adviseble and affordable. Don't remember this being mentioned when we picked up the camper.

 

[DirtyDog]

Why do they build roads with concrete vs asphalt anyway?

 

[chnlisle]

Just in case AirForce 1 needs to land in Covina?

 

[pvstoy]

I'll try to answer some of your questions:

PCCP – Portland Cement Concrete Pavement
PBS – Plantmix Bituminous Surface

PCCP is used for it’s longevity with a life around 30 years. PBS is designed for about 20 years but without some money to keep maintained up front it will last about 6 years on the Interstates.

With the PCCP you will get the loading at the expansion joints and will pump on the subbase. Water travels down the joints and helps accelerate the washout of fines under the concrete. Then you will have voids so the slabs rock. If the voids are enough there will be cracking of the PCCP and it will have to be cut out and replaced.

There are Dowel Bar Retrofits that will tie the two slabs together and still allow the slabs to expand and contract due to temperature.

In the surface of the PCCP there are groves that are there to move the water outward to the edge of pavement. That will cause the road to be rougher and noisier.

PBS over time it will loose its elasticity, and when it shrinks up in the cold will get longitude cracks and need to be sealed up from water getting in. Water is a problem.

 

[Mark W. Ingalls]

I love learning about stuff!

Patrick, that was a way cool read!

Thanks!

 

[chnlisle]

This site just blows me away.

 

[DLN]

Patrick,

Great explanation, you detailed all the information I was too lazy to post or had forgotten over the years, thanks.

 

[ColoradoGuy]

Wow

Patrick, that was an amazing post. But I'm still wondering about replacing the shocks. Since the my last post, someone pointed out that my leaf springs seem to be fully stressed. May have to check in with the dealer. Geez. Thanks to all who passed on information.

 

[pvstoy]

Leafsprings carry the load.

Shocks dampen the travel.

If your springs are not keeping up with the load then there will be more work from the shocks to try to dampen the travel. In return the shocks are going to heat up more and wear out sooner.

Address the load part - springs - then a pair of good shocks will last a very long time.

 

[Stan@FourWheel]

here are a few companies you can look at that sell helper springs and air bags ...

www.hellwigproducts.com

www.supersprings.com

www.sport-rite.com



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