Raising Overpasses

[Fred Defender]

It's been a number of months since I've checked in here. And it is possible that I have already asked this (hey, I'm old). But I'm sure that the vast wealth of knowledge on this forum will provide an answer:

Exactly HOW do they "raise" an existing overpass? Below is a photo of an overpass along I-75 in Tift County, GA. There are a number of circa 1958 overpasses in this area that have been raised to allow for greater overhead clearance. I've seen the same thing done on several overpasses along I-71 between Cincinnati and Columbus, OH as well.

How on Earth do they do this? I've searched online and haven't been able to find a web site that describes the procedure. For a 50+ year old structure, I would think that it would be easier and less expensive to just start from scratch. Or perhaps modifying the grade underneath the overpass.

Anyway...just curious.

[Jardine]

Highway 30 and Interstate 29 north of Omaha/Council Bluffs took a little different tactic with that clearance problem.

[2Co5_14]

Here are links to a couple of bridge raising projects that describe and/or show the process:

http://www.mcgee-engineering.com/AlbusRaising
http://www.raise80.com/about-2/

It is generally a lot easier and less disruptive to traffic to raise the grade and profile of a minor road overpass than it is to lower the grade and profile of a major freeway.  To lower the freeway, you would need to tear out and completely replace thousands of feet of pavement in either direction to avoid having a noticeable "dip" for high speed vehicles traveling on it.  You would also need to adjust any drainage structures in the area and re-grade the shoulders.

[Fred Defender]

Here are links to a couple of bridge raising projects that describe and/or show the process:

http://www.mcgee-engineering.com/AlbusRaising
http://www.raise80.com/about-2/

It is generally a lot easier and less disruptive to traffic to raise the grade and profile of a minor road overpass than it is to lower the grade and profile of a major freeway.  To lower the freeway, you would need to tear out and completely replace thousands of feet of pavement in either direction to avoid having a noticeable "dip" for high speed vehicles traveling on it.  You would also need to adjust any drainage structures in the area and re-grade the shoulders.

Cool. Thanks a lot for the links. It's still some pretty darned interesting engineering that's involved. I still question the viability of doing this to a structure that's 50+ years old - especially on I-75 in Georgia where they're replaced a number of late-50's/early-60's overpasses in recent years. But, then again, I guess they wouldn't do it if it didn't make economic sense (would they?).

I had not considered the drainage issues that you mentioned (i.e., lowering the grade of the under-passing interstate). Indeed, you would not want to create a giant retention pond on I-75. So thanks for pointing that out.

Again, very neat. I knew that I came to the right place!

[Jardine]

And at I-29 and Highway 30, they did in fact lower Highway 30 to make more clearance.  The dip isn't very well camouflaged at all, it is very noticeable and to my eye, looks really rinky-dink.

When they hauled in the dirt for the overpass, it was quite a production, and as I recall, went on for an entire summer.  The incremental addition of dirt back in the 60s to have done it correctly in the first place was probably trivial compared to what it cost to do what they did do.  Additionally, they had an unlimited supply of dirt back then, they built a special road to haul it on, and as I recall, the hauling distance was around a mile.

The dip is a black mark on highway execution.

[busman_49]

When I-71 from outside of Cleveland to north of Columbus was rebuilt and widened in the 2000s and early 2010s, they lowered 71 in places to make more clearance.  Since the whole thing was being rebuilt, I imagine doing things that way made more sense than trying to raise bridges.  There are no noticeable dips and no retention pond issues (that I know of)

[txstateends]

So far, all of the replacement bridges and ramps in the downtown Dallas 'horseshoe' project (where I-35E and I-30 meet and their Trinity River spans) have been built higher than what they've been replacing.

[jeffandnicole]

https://goo.gl/maps/KJn89mi93mx

At this overpass on I-295 South in NJ, a truck hit the overpass, causing some serious damage (a hydraulic lift failed, causing the bed of a truck to rise, hitting the overpass.  The southbound side was replaced using smaller steel beams to allow for a greater clearance.  This entire overpass will probably be replaced in the next few years as a result of a construction project separate from the construction you see in the GSV link above.

[Jardine]

The highway 30 overpass in Missouri Valley Iowa over the UP double track (former C&NW) was purposely built (98 or 2000 as I recall) over height above the newly laid cement double tracks so if in the future the rails needed raised, the overpass could still accommodate it.

Lo and behold, 2011 during the Army Corp of Engineers Missouri River Flood, UP went ahead and raised the tracks 2 to 3 feet to hopefully stay above the flood waters (which they did).

Good instance of planning ahead.

BTW, I watched the machinery that raised the trackage.  Pretty interesting, they first all but bury the track in excess ballast, then a machine comes along and pulls the the rails and ties above the new ballast.  Then the track is again nearly buried, and raised out of the ballast again.  Repeat till it's high enough. The raised it 2-3 feet that way. UP set up lights and threw an enormous amount of resources at the problem and kept the line open throughout the flood.  I'm thinking serious concerns about a major levee failure in Council Bluffs that could have flooded their entire CB yard facility and literally strangled rail traffic across the country was the impetus.

[Pete from Boston]

The highway 30 overpass in Missouri Valley Iowa over the UP double track (former C&NW) was purposely built (98 or 2000 as I recall) over height above the newly laid cement double tracks so if in the future the rails needed raised, the overpass could still accommodate it.

Lo and behold, 2011 during the Army Corp of Engineers Missouri River Flood, UP went ahead and raised the tracks 2 to 3 feet to hopefully stay above the flood waters (which they did).

Good instance of planning ahead.

BTW, I watched the machinery that raised the trackage.  Pretty interesting, they first all but bury the track in excess ballast, then a machine comes along and pulls the the rails and ties above the new ballast.  Then the track is again nearly buried, and raised out of the ballast again.  Repeat till it's high enough. The raised it 2-3 feet that way. UP set up lights and threw an enormous amount of resources at the problem and kept the line open throughout the flood.  I'm thinking serious concerns about a major levee failure in Council Bluffs that could have flooded their entire CB yard facility and literally strangled rail traffic across the country was the impetus.

This sounds like a prolonged repeated version of what happens for more routine ballast addition.  I recall seeing this being done at least once in years of living along railroads as the (coarsely) granular ballast settles over time.

[theline]

When the first part of South Bend's US 20 bypass was built, in the 1950's IIRC, the underpasses were built with lower clearance that is now acceptable. A few years ago that was rectified by replacing the Locust Road, Ireland Road, and Crumstown Highway bridges. INDOT took the other approach to the SR 23 underpass, lowering US 20/31 by several feet. It was done so skillfully that drivers would have no idea the road was lowered. I checked historic GSV, hoping for a comparison view, but it doesn't go back far enough for any "before" pictures.

[DrSmith]

A couple of years back they raised the Enfield St bridge (Route 5) over I-91 at Exit 49 in Conn during a rehabilitation project. They added concrete to raise the piers creating more clearance, then put down new steel girders and new structure.  I think it was 13'11" or so prior. It was done in stages so the bridge remained open while they worked on it.

[cpzilliacus]

PennDOT and NCDOT have both raised bridges over freeways.

PennDOT seems to like to remove the stringers, raise the pier caps, regrade the road leading up to the bridge, and then put it all back together.

NCDOT (along I-95) seems to prefer to remove the stringers, raise the pier caps, and then install new stringers that are not as tall as the ones removed, so the smaller road does not need much regrading.

[Tom958]

I wish I'd seen this when it was current... 

I don't get down that way much, but my memory is that the bridges that were raised were of the concrete T beam type shown in FredDefender's photo, and they're found north of Tifton. South of Tifton, the bridges were of pre-AASHTO beam precast construction and were replaced with modern, much longer AASHTO beam spans when I-75 was rebuilt. My theory, which may or may not be correct, is that the T beam bridges were of monolithic construction and were therefore both easier to raise and harder to demolish without disrupting traffic than the precast bridges with their simple spans. Plus, the project undertaken north of Tifton was earlier and much more limited in general scope-- the existing pavement was overlaid with asphalt, not removed and replaced with concrete as was done south of Tifton.

When I-71 from outside of Cleveland to north of Columbus was rebuilt and widened in the 2000s and early 2010s, they lowered 71 in places to make more clearance.  Since the whole thing was being rebuilt, I imagine doing things that way made more sense than trying to raise bridges.  There are no noticeable dips and no retention pond issues (that I know of)

I know nothing about I-71 in Ohio, but...

Reading the project concept report for rebuilding I-85 north of Atlanta, I learned that the standard k factors for Interstates were increased in 2004, One reason why the pavement on 85 is to be removed and replaced is so that the profile can be improved as well, even though it's on mid '60's vintage and noticeably better that it is in the Carolinas.  So, could it be that the I-71 roadway was lowered to improve its profile, with increased bridge clearances being a happy side effect?

[1995hoo]

On I-495 in Virginia as part of the Wilson Bridge project they simply re-routed traffic onto the other side of the street, knocked down one side and built a new, higher overpass, re-routed the traffic onto that, then repeated for the other side.

Downside of this approach is that if there's an older overpass with unique guardrails or the like you lose those. It's a shame when progress means losing unique things.

[74/171FAN]

PennDOT and NCDOT have both raised bridges over freeways.

PennDOT seems to like to remove the stringers, raise the pier caps, regrade the road leading up to the bridge, and then put it all back together.

NCDOT (along I-95) seems to prefer to remove the stringers, raise the pier caps, and then install new stringers that are not as tall as the ones removed, so the smaller road does not need much regrading.

Well there have been two overpasses hit by trucks within the last two months (Burgs Lane over US 30 near Wrightsville and Landis Valley Road over US 222 near Lancaster).  It will be interesting to see what comes out of this considering the former has been hit a couple times in the past (and fixed at least a couple times in the past as well).

[TEG24601]

ODOT did it in Portland around the turn of the century on I-5's "Minnesota Freeway" portion and along the Eastbank of the Willamette through the Rose Quarter. - http://djcoregon.com/news/2001/04/30/i5-preservation-project-will-cause-summer-closures/


In this case, you can see discoloration on the bridge supports to show where the inserted new sections.  I recall some place when driving cross-country, where they lowered the roadway to get the same result.