I'm curious to know what part of it is the most expensive? Is it site preparation? Is it just the amount of concrete and steel needed?
Earthwork and the bridge quantities.
Quantities are all things needed to build something. Think of it as the receipt when you design a project. You list all items needed to build something and how much of it you need. You use those quantities to estimate the cost of the project. In the case of your question it's the cost of all the dirt work and all the things needed to build a bridge that makes it expensive. Buying right of way (buying property) can also be very expensive.
I'd think there are lots of variables depending on location and project size that could mean the most expensive part will differ by project, sometimes quite significantly.
Quote from: 1995hoo on October 11, 2020, 09:27:32 PM
I'd think there are lots of variables depending on location and project size that could mean the most expensive part will differ by project, sometimes quite significantly.
Definitely true. Rural projects can be more expensive than you think simply because it costs a lot to haul materials out to the project
Quote from: silverback1065 on October 11, 2020, 09:26:01 PM
Quantities are all things needed to build something. Think of it as the receipt when you design a project. You list all items needed to build something and how much of it you need. You use those quantities to estimate the cost of the project. In the case of your question it's the cost of all the dirt work and all the things needed to build a bridge that makes it expensive. Buying right of way (buying property) can also be very expensive.
Okay, what's so expensive about building a bridge?
Quote from: kernals12 on October 11, 2020, 09:33:34 PM
Quote from: silverback1065 on October 11, 2020, 09:26:01 PM
Quantities are all things needed to build something. Think of it as the receipt when you design a project. You list all items needed to build something and how much of it you need. You use those quantities to estimate the cost of the project. In the case of your question it's the cost of all the dirt work and all the things needed to build a bridge that makes it expensive. Buying right of way (buying property) can also be very expensive.
Okay, what's so expensive about building a bridge?
Pile driving the supports, all the concrete, rebar, etc. I'm not a structural engineer but I do know all of that and more makes it pretty expensive.
Presumably it's not just building a bridge, either–if there's an existing intersection, most likely some level of access will be retained, and that's likely to require a wider right-of-way for the ramps, which in turn may require acquiring property (whether via eminent domain or some other means will vary). The cost of the property is a variable.
Quote from: 1995hoo on October 11, 2020, 09:37:44 PM
Presumably it's not just building a bridge, either–if there's an existing intersection, most likely some level of access will be retained, and that's likely to require a wider right-of-way for the ramps, which in turn may require acquiring property (whether via eminent domain or some other means will vary). The cost of the property is a variable.
But what if the intersection currently has a bunch of left turn lanes taking up space?
Quote from: kernals12 on October 11, 2020, 09:59:59 PM
Quote from: 1995hoo on October 11, 2020, 09:37:44 PM
Presumably it's not just building a bridge, either–if there's an existing intersection, most likely some level of access will be retained, and that's likely to require a wider right-of-way for the ramps, which in turn may require acquiring property (whether via eminent domain or some other means will vary). The cost of the property is a variable.
But what if the intersection currently has a bunch of left turn lanes taking up space?
What do you mean?
Quote from: kernals12 on October 11, 2020, 09:59:59 PM
Quote from: 1995hoo on October 11, 2020, 09:37:44 PM
Presumably it's not just building a bridge, either–if there's an existing intersection, most likely some level of access will be retained, and that's likely to require a wider right-of-way for the ramps, which in turn may require acquiring property (whether via eminent domain or some other means will vary). The cost of the property is a variable.
But what if the intersection currently has a bunch of left turn lanes taking up space?
See boldfaced word.
Quote from: silverback1065 on October 11, 2020, 10:05:42 PM
Quote from: kernals12 on October 11, 2020, 09:59:59 PM
Quote from: 1995hoo on October 11, 2020, 09:37:44 PM
Presumably it's not just building a bridge, either–if there's an existing intersection, most likely some level of access will be retained, and that's likely to require a wider right-of-way for the ramps, which in turn may require acquiring property (whether via eminent domain or some other means will vary). The cost of the property is a variable.
But what if the intersection currently has a bunch of left turn lanes taking up space?
What do you mean?
With an overpass, the space taken up by the left turns can be repurposed.
Quote from: kernals12 on October 11, 2020, 10:19:12 PM
Quote from: silverback1065 on October 11, 2020, 10:05:42 PM
Quote from: kernals12 on October 11, 2020, 09:59:59 PM
Quote from: 1995hoo on October 11, 2020, 09:37:44 PM
Presumably it's not just building a bridge, either–if there's an existing intersection, most likely some level of access will be retained, and that's likely to require a wider right-of-way for the ramps, which in turn may require acquiring property (whether via eminent domain or some other means will vary). The cost of the property is a variable.
But what if the intersection currently has a bunch of left turn lanes taking up space?
What do you mean?
With an overpass, the space taken up by the left turns can be repurposed.
It depends on the geometry, it may not matter, it could be just enough room for the piers (the vertical structure in the middle of the bridge)
Quote from: silverback1065 on October 11, 2020, 09:35:20 PM
Quote from: kernals12 on October 11, 2020, 09:33:34 PM
Quote from: silverback1065 on October 11, 2020, 09:26:01 PM
Quantities are all things needed to build something. Think of it as the receipt when you design a project. You list all items needed to build something and how much of it you need. You use those quantities to estimate the cost of the project. In the case of your question it's the cost of all the dirt work and all the things needed to build a bridge that makes it expensive. Buying right of way (buying property) can also be very expensive.
Okay, what's so expensive about building a bridge?
Pile driving the supports, all the concrete, rebar, etc. I'm not a structural engineer but I do know all of that and more makes it pretty expensive.
Do you think that stronger lightweight materials in the future could make such bridges less expensive?
Not likely. Remember, bridges aren't the only things that use steel and concrete. They have to compete with other building projects for those resources, and generally that takes the form of the price going up.
Labor is a huge cost center, too. Engineers have specialized knowledge and are expensive to hire. Working on bridges is a dangerous job, so you can't pay peanuts and expect to have anyone show up and build (remember, you have to compete for them too–if you can score a safe indoor job remodeling an office building that pays the same as the bridge project, who wants to build a stinkin' bridge?) And, of course one of the biggest cost sinks is going through the environmental approval process, which involves lawyers. None of these labor costs is ever going to go down.
Quote from: Scott5114 on October 12, 2020, 12:45:21 AM
Not likely. Remember, bridges aren't the only things that use steel and concrete. They have to compete with other building projects for those resources, and generally that takes the form of the price going up.
Labor is a huge cost center, too. Engineers have specialized knowledge and are expensive to hire. Working on bridges is a dangerous job, so you can't pay peanuts and expect to have anyone show up and build (remember, you have to compete for them too–if you can score a safe indoor job remodeling an office building that pays the same as the bridge project, who wants to build a stinkin' bridge?) And, of course one of the biggest cost sinks is going through the environmental approval process, which involves lawyers. None of these labor costs is ever going to go down.
the environmental process can take multiple years depending on the size of a job.
You also have to consider whats nearby. Businesses located in the corners of the intersection will lose some or all of their access to the existing roadways.
NJ is a high priced construction state, but to use one project as an example, converting 70/73 from a circle to an overpass cost about $50 million.
A few examples in Delaware:
The cost of this project is about $69 million:
https://www.capegazette.com/article/overpass-proposed-routes-113-and-404/198308
And this one was about $40 million:
https://www.delawarepublic.org/post/new-route-1-overpass-little-heaven-open-next-week
Quote from: kernals12 on October 11, 2020, 07:59:06 PM
I'm curious to know what part of it is the most expensive? Is it site preparation? Is it just the amount of concrete and steel needed?
By the way, are you only talking about grade separation, or are you talking about an interchange? That is to say, an overpass does not imply access from one road to another. Adding access ramps etc increases not only the amount of grading and concrete work, but also the amount of land acquisition.
Quote from: kphoger on October 12, 2020, 03:13:29 PM
Quote from: kernals12 on October 11, 2020, 07:59:06 PM
I'm curious to know what part of it is the most expensive? Is it site preparation? Is it just the amount of concrete and steel needed?
By the way, are you only talking about grade separation, or are you talking about an interchange? That is to say, an overpass does not imply access from one road to another. Adding access ramps etc increases not only the amount of grading and concrete work, but also the amount of land acquisition.
I'm talking about a diamond interchange.
If one of the roads is significantly below grade, that is one road "tunnels" under the other, you need a pumping system to prevent flooding.
And with the additional pavement required by the diamond interchange, many areas might require construction of an adjacent pond or some other form of stormwater mitigation. A good thing, IMHO.
Quote from: lepidopteran on October 12, 2020, 07:37:27 PM
If one of the roads is significantly below grade, that is one road "tunnels" under the other, you need a pumping system to prevent flooding.
And with the additional pavement required by the diamond interchange, many areas might require construction of an adjacent pond or some other form of stormwater mitigation. A good thing, IMHO.
This is something that is studied on every project and can increase the cost a lot! SR 37 in Fishers, IN had an over 1 million dollar cost increase due to drainage changes. Also a rule 5 permit is required and that is drainage related.
Quote from: silverback1065 on October 12, 2020, 08:11:31 PM
Quote from: lepidopteran on October 12, 2020, 07:37:27 PM
If one of the roads is significantly below grade, that is one road "tunnels" under the other, you need a pumping system to prevent flooding.
And with the additional pavement required by the diamond interchange, many areas might require construction of an adjacent pond or some other form of stormwater mitigation. A good thing, IMHO.
This is something that is studied on every project and can increase the cost a lot! SR 37 in Fishers, IN had an over 1 million dollar cost increase due to drainage changes. Also a rule 5 permit is required and that is drainage related.
Most grade separation projects cost tens of millions so an extra 1 million for drainage isn't that big of a deal.
Quote from: kernals12 on October 12, 2020, 10:43:50 PM
Quote from: silverback1065 on October 12, 2020, 08:11:31 PM
Quote from: lepidopteran on October 12, 2020, 07:37:27 PM
If one of the roads is significantly below grade, that is one road "tunnels" under the other, you need a pumping system to prevent flooding.
And with the additional pavement required by the diamond interchange, many areas might require construction of an adjacent pond or some other form of stormwater mitigation. A good thing, IMHO.
This is something that is studied on every project and can increase the cost a lot! SR 37 in Fishers, IN had an over 1 million dollar cost increase due to drainage changes. Also a rule 5 permit is required and that is drainage related.
Most grade separation projects cost tens of millions so an extra 1 million for drainage isn't that big of a deal.
It is when that increase happens after construction starts. [emoji15]
Quote from: silverback1065 on October 12, 2020, 10:47:12 PM
Quote from: kernals12 on October 12, 2020, 10:43:50 PM
Quote from: silverback1065 on October 12, 2020, 08:11:31 PM
Quote from: lepidopteran on October 12, 2020, 07:37:27 PM
If one of the roads is significantly below grade, that is one road "tunnels" under the other, you need a pumping system to prevent flooding.
And with the additional pavement required by the diamond interchange, many areas might require construction of an adjacent pond or some other form of stormwater mitigation. A good thing, IMHO.
This is something that is studied on every project and can increase the cost a lot! SR 37 in Fishers, IN had an over 1 million dollar cost increase due to drainage changes. Also a rule 5 permit is required and that is drainage related.
Most grade separation projects cost tens of millions so an extra 1 million for drainage isn't that big of a deal.
It is when that increase happens after construction starts. [emoji15]
You'll be surprised how normal that for large projects.
It also draws into question why this wasn't engineered properly in the first place.
And I'm guessing Rule 5, whatever that is, is something related to the state you're referring to.
In a congested and busy commercial area, right-of-way acquisition could well be the #1 cost item.
Mike
Quote from: mgk920 on October 13, 2020, 03:26:34 AM
In a congested and busy commercial area, right-of-way acquisition could well be the #1 cost item.
Mike
I thinking of suburban arterial streets which already have an absurd number of left turn lanes.
Quote from: kernals12 on October 13, 2020, 04:37:45 PM
I thinking of suburban arterial streets which already have an absurd number of left turn lanes.
Residents probably wouldn't much care for an elevated bridge in that environment, so you'd probably be looking at sinking the lower roadway below grade–in which case the previous comment about flood mitigation definitely comes into play. Land acquisition will likely include strips of each property along the affected roadway–whether elevated or sunken–even without ramps, which you've already said would be in the plan. A plan will need to be made for access to the properties that will no longer have direct access to the affected roadway(s).
One alternative that might be more cost-effective (but also might have lower capacity) is a grade-separated quadrant intersection. See
IL-38/IL-53 (https://goo.gl/maps/y48Y6V91Mfiy4YFR6) and
IL-83/IL-19 (https://goo.gl/maps/81M528JV3sC6Ajof7) in suburban Chicago as two examples.
Quote from: kphoger on October 13, 2020, 04:51:03 PM
One alternative that might be more cost-effective (but also might have lower capacity) is a grade-separated quadrant intersection. See IL-38/IL-53 (https://goo.gl/maps/y48Y6V91Mfiy4YFR6) and IL-83/IL-19 (https://goo.gl/maps/81M528JV3sC6Ajof7) in suburban Chicago as two examples.
Technically, capacity is higher because traffic can free-flow at these intersections. It would need to be considered where an intersection can be placed that will allow access between both roadway, if it ultimately is a plus or minus for capacity in the entire corridor.
NJ actually built a number of these back in the day, when the money was flowing and things could really be squeezed in. https://goo.gl/maps/quEvoqGr8Mymo5M27 is one such example, in which the cross street became RIROs, and a very small bypass allowed for free-flow movements, while 130 wasn't interrupted at all.
Quote from: kphoger on October 13, 2020, 04:51:03 PM
Quote from: kernals12 on October 13, 2020, 04:37:45 PM
I thinking of suburban arterial streets which already have an absurd number of left turn lanes.
Residents probably wouldn't much care for an elevated bridge in that environment, so you'd probably be looking at sinking the lower roadway below grade–in which case the previous comment about flood mitigation definitely comes into play. Land acquisition will likely include strips of each property along the affected roadway–whether elevated or sunken–even without ramps, which you've already said would be in the plan. A plan will need to be made for access to the properties that will no longer have direct access to the affected roadway(s).
One alternative that might be more cost-effective (but also might have lower capacity) is a grade-separated quadrant intersection. See IL-38/IL-53 (https://goo.gl/maps/y48Y6V91Mfiy4YFR6) and IL-83/IL-19 (https://goo.gl/maps/81M528JV3sC6Ajof7) in suburban Chicago as two examples.
If the arterial is lined with strip malls and car dealerships, I don't think they'll care.
Quote from: kernals12 on October 13, 2020, 06:43:02 PM
Quote from: kphoger on October 13, 2020, 04:51:03 PM
Quote from: kernals12 on October 13, 2020, 04:37:45 PM
I thinking of suburban arterial streets which already have an absurd number of left turn lanes.
Residents probably wouldn't much care for an elevated bridge in that environment, so you'd probably be looking at sinking the lower roadway below grade–in which case the previous comment about flood mitigation definitely comes into play. Land acquisition will likely include strips of each property along the affected roadway–whether elevated or sunken–even without ramps, which you've already said would be in the plan. A plan will need to be made for access to the properties that will no longer have direct access to the affected roadway(s).
One alternative that might be more cost-effective (but also might have lower capacity) is a grade-separated quadrant intersection. See IL-38/IL-53 (https://goo.gl/maps/y48Y6V91Mfiy4YFR6) and IL-83/IL-19 (https://goo.gl/maps/81M528JV3sC6Ajof7) in suburban Chicago as two examples.
If the arterial is lined with strip malls and car dealerships, I don't think they'll care.
They may care more about the lack of access to the main road if it's cut off.
But people are funny. They'll also say it'll lower their property value, even if their siding is falling off, the neighbor across the street had 3 junkers sitting on the front lawn, and they have no plans on moving, ever.
One huge cost item that has not been mentioned yet, and often dwarfs mgk's argument about right-of-way costs being #1, is traffic control. Maintaining traffic through a construction zone, especially one with complex project phasing, is costly.
Quote from: froggie on October 14, 2020, 11:43:52 AM
One huge cost item that has not been mentioned yet, and often dwarfs mgk's argument about right-of-way costs being #1, is traffic control. Maintaining traffic through a construction zone, especially one with complex project phasing, is costly.
Nowadays, the primary type of phasing is nightly shutdowns. This forces the hourly wages up and limits the work hours to usually a five or six hour window. We were fortunate that NCDOT was able to completely shut down the section of (then) Green 40 through Winston-Salem to redevelop the US-421 Salem Parkway at a reasonable cost.
Not everyone does nightly shutdowns. I live in a state where, except on a handful of roads in one county, they almost never do overnight closures or night work.
Quote from: froggie on October 15, 2020, 12:50:21 AM
Not everyone does nightly shutdowns. I live in a state where, except on a handful of roads in one county, they almost never do overnight closures or night work.
Reasons for that are in my experience to minimize noise impacts on the surrounding residences, or to minimize costs as labour costs tend to have a premium on overnights/weekends. But that latter is balancing costs, whether it's necessary for the staging to have lower traffic volumes or to have the work done sooner (though ultimately within the same number of working days, so sooner isn't likely to save you anything there).
Quote from: kernals12 on October 13, 2020, 06:43:02 PM
Quote from: kphoger on October 13, 2020, 04:51:03 PM
Quote from: kernals12 on October 13, 2020, 04:37:45 PM
I thinking of suburban arterial streets which already have an absurd number of left turn lanes.
Residents probably wouldn't much care for an elevated bridge in that environment, so you'd probably be looking at sinking the lower roadway below grade–in which case the previous comment about flood mitigation definitely comes into play. Land acquisition will likely include strips of each property along the affected roadway–whether elevated or sunken–even without ramps, which you've already said would be in the plan. A plan will need to be made for access to the properties that will no longer have direct access to the affected roadway(s).
One alternative that might be more cost-effective (but also might have lower capacity) is a grade-separated quadrant intersection. See IL-38/IL-53 (https://goo.gl/maps/y48Y6V91Mfiy4YFR6) and IL-83/IL-19 (https://goo.gl/maps/81M528JV3sC6Ajof7) in suburban Chicago as two examples.
If the arterial is lined with strip malls and car dealerships, I don't think they'll care.
They very much care in many situations. even can kill the project. you hear things like "business will go down due to construction" or "permanent loss of business due to loss of access" US 31 in Carmel, IN actually killed 3 strip malls due to lack of access.
Quote from: froggie on October 15, 2020, 12:50:21 AM
Not everyone does nightly shutdowns. I live in a state where, except on a handful of roads in one county, they almost never do overnight closures or night work.
Quote from: cbeach40 on October 15, 2020, 01:28:05 AM
Reasons for that are in my experience to minimize noise impacts on the surrounding residences, or to minimize costs as labour costs tend to have a premium on overnights/weekends. But that latter is balancing costs, whether it's necessary for the staging to have lower traffic volumes or to have the work done sooner (though ultimately within the same number of working days, so sooner isn't likely to save you anything there).
In my youth, it was not unusual for contractors to hang stringers over top of an operating roadway. Oops (not smart). Most bridge projects would prefer to schedule about one work week of unobstructed access per span over an existing thoroughfare. Obviously, they can do this faster but it is becomes a big logistics puzzle (with multiple backup plans). But there's any number of ways to get unobstructed access. Once upon a time in West Virginia, the DOH would construct temporary ramps to the elevated section of crossroad and use them as construction detours (and remove them afterward).