Piers without caps?

[lepidopteran]

Ever notice that some highway overpasses are constructed with multiple pier elements, but no "pier cap" across the tops of them?  That is, piers are essentially standalone columns?  Think of those children's building blocks that are in the shape of a cylinder.  These seem so much more flimsy than piers with caps, especially during construction.  Sometimes, one or more of these standalone cylinders may be added to the outside of an existing overpass when a lane and/or shoulder is added, but I've seen some with no pier cap whatsoever.

Here's an example; notice that there's a "square" wing wall on either side, as opposed to the wider, slanted embankment used for most other bridges, at least on that highway.
https://www.google.com/maps/preview?hl=en#!data=!1m8!1m3!1d3!2d-83.61468!3d41.685431!2m2!1f83.4!2f88.27!4f75!2m4!1e1!2m2!1sJvDswIP9XtHUK5Lg9MFn8A!2e0&fid=5

This is I-475 at Monroe St. in Toledo, OH.  Only two directional movements are possible at this interchange.

Anyone know the engineering rationale on why those types of piers are sometimes more desirable?

[roadman65]

I-295 in New Jersey has many of them.

[Big John]

My first worry is piers 2 and 3 in the median.  Those need to be repaired quickly before they become structurally unsound. The spalling should never be allowed to get that bad without repair.

But with your question, though less likely for bridges with girders, they do exist, more likely if the bridge is not at a 90 degree angle.  The bridge did go through a structural analysis before being built, and that was most likely the most economical sound design found.

Those are more likely found on reinforced slab bridges, where there are no girders at all.

[vtk]

In my part of Ohio, most rural bridges over freeways carry two-lane roads.  The bridge deck is supported by four steel girders, which rest on caps over groups of two piers.  If the road is not at a right angle, but off a little bit, then the bridge is longer and heavier, so groups of three piers are used.  When the angle is more acute than about 45 degrees, groups of four piers are used.  In that case, a one to one mapping of girders on piers means no cap is necessary.

[Bitmapped]

In my part of Ohio, most rural bridges over freeways carry two-lane roads.  The bridge deck is supported by four steel girders, which rest on caps over groups of two piers.  If the road is not at a right angle, but off a little bit, then the bridge is longer and heavier, so groups of three piers are used.  When the angle is more acute than about 45 degrees, groups of four piers are used.  In that case, a one to one mapping of girders on piers means no cap is necessary.

Actually, Ohio's usage tends to vary more by when the bridge was constructed.  During the bulk of the Interstate era, Ohio's standard was 3 piers tied together with a cap.  The state did some stuff around the 1980s with other designs (two piers with a cap, one pier, etc.) but generally went back to a modified version of the 3 pier-with-cap in the 1990s because it provides redundancy if one of the piers is struck.

ODOT generally omits pier caps and places piers under each girder when the bridge doesn't cross at a 90-degree angle.

[vtk]

In my part of Ohio, most rural bridges over freeways carry two-lane roads.  The bridge deck is supported by four steel girders, which rest on caps over groups of two piers.  If the road is not at a right angle, but off a little bit, then the bridge is longer and heavier, so groups of three piers are used.  When the angle is more acute than about 45 degrees, groups of four piers are used.  In that case, a one to one mapping of girders on piers means no cap is necessary.

Actually, Ohio's usage tends to vary more by when the bridge was constructed.  During the bulk of the Interstate era, Ohio's standard was 3 piers tied together with a cap.  The state did some stuff around the 1980s with other designs (two piers with a cap, one pier, etc.) but generally went back to a modified version of the 3 pier-with-cap in the 1990s because it provides redundancy if one of the piers is struck.

ODOT generally omits pier caps and places piers under each girder when the bridge doesn't cross at a 90-degree angle.

I was referring to the freeways in the part of Ohio with which I'm most familiar, that being I-70 and I-71 west of Columbus.  I think that's pretty much all 1960s construction.  Most of these bridges which cross at or close to 90 degrees (which isn't many of them) have sets of two piers, not three.  I'm pretty sure the number of piers (from this design era) is related directly to span length, which is primarily dependent on the crossing angle, and bridge width, which doesn't vary much.  Piers are omitted usually if, and only if, the number of piers in a set is equal to the number of girders, plain and simple; this is only indirectly related to crossing angle and design era.

[NJRoadfan]

I-295 in New Jersey has many of them.

http://goo.gl/maps/l5K9S

Only that section between the DMB and US-130. Its also the only highway I've seen that type of bridge construction in the entire state.

[BrianP]

I-295 in New Jersey has many of them.

http://goo.gl/maps/l5K9S

Only that section between the DMB and US-130. Its also the only highway I've seen that type of bridge construction in the entire state.

There are also some on the N-S Freeway I-76/NJ 42:
http://goo.gl/maps/VjST0
http://goo.gl/maps/S4dkz
http://goo.gl/maps/78wCe

[SteveG1988]

I-295 over Marne Highway, Burlington County Route 537, between hainesport and Moorestown NJ
http://goo.gl/maps/SbuV0

[Scott5114]

The old I-40 Crosstown in Oklahoma City used this design.

[rte66man]

The old I-40 Crosstown in Oklahoma City used this design.

Many of the remaining bridges west of there (on what will become the "Boulevard") have that design as well.

rte66man

[roadman65]

The bridge carrying I-295 over the NJ Turnpike PA Extension has them.

https://maps.google.com/maps?q=Mansfield,+NJ&hl=en&ll=40.095276,-74.750247&spn=0.014675,0.035791&sll=39.975476,-74.901009&sspn=0.029565,0.071583&oq=mans&t=h&gl=us&hnear=Mansfield,+Burlington,+New+Jersey&z=16&layer=c&cbll=40.095172,-74.751111&panoid=xWpvYle7DUp6CiPNe8qjvQ&cbp=12,135.08,,0,-0.08

[jeffandnicole]

I-295 over US 130 (Bordentown Twp, Exit 57) has them as well: http://goo.gl/maps/miITr

[SteveG1988]

I-295 over US 130 (Bordentown Twp, Exit 57) has them as well: http://goo.gl/maps/miITr

The bridge carrying I-295 over the NJ Turnpike PA Extension has them.

https://maps.google.com/maps?q=Mansfield,+NJ&hl=en&ll=40.095276,-74.750247&spn=0.014675,0.035791&sll=39.975476,-74.901009&sspn=0.029565,0.071583&oq=mans&t=h&gl=us&hnear=Mansfield,+Burlington,+New+Jersey&z=16&layer=c&cbll=40.095172,-74.751111&panoid=xWpvYle7DUp6CiPNe8qjvQ&cbp=12,135.08,,0,-0.08

NJ38 over 295
http://goo.gl/maps/ZKhyz

Might have been something NJDOT tried in the 70s