Virginia

[froggie]

From personal experience, it'd be a very tight fit for 3 lanes under each existing span...and you'd basically have no room for crash protection for the bridge columns.

If you hollowed out the embankment on each side, that'd be one potential way to get two additional lanes on Witchduck without replacing the overpasses.  But then you'd have the operational issues of having such a lane split (and downstream rejoin).

[Beltway]

From personal experience, it'd be a very tight fit for 3 lanes under each existing span...and you'd basically have no room for crash protection for the bridge columns.
If you hollowed out the embankment on each side, that'd be one potential way to get two additional lanes on Witchduck without replacing the overpasses.  But then you'd have the operational issues of having such a lane split (and downstream rejoin).

That is about what I thought.

The correct solution would be replacing the bridges with longer span bridges.

Centerline width over Witchduck Road is 170 feet, so there is a large bridge structure there.

[sprjus4]

While I agree the long-term solution should be bridge replacement, the Military Highway widening project had a similar issue with the narrow horizontal clearance under the I-64 overpass, though they managed to squeeze 3 lanes in the southbound direction.

Here's a before and after.

[Beltway]

While I agree the long-term solution should be bridge replacement, the Military Highway widening project had a similar issue with the narrow horizontal clearance under the I-64 overpass, though they managed to squeeze 3 lanes in the southbound direction.

I get 34 feet of clearance possible southbound and 32 feet of clearance possible northbound.

That is after installing the concrete traffic barriers in front of the piers.

That is very tight and then it gets into how even with 3 lanes there might not be much of an increase in capacity.

[sprjus4]

then it gets into how even with 3 lanes there might not be much of an increase in capacity.

On Witchduck Rd or Military Highway?

If you're referring to Witchduck Rd, then I would disagree. That road is a major bottleneck, and all of it is being widened to 6-lanes north of I-264, and was recently widened to 6-lanes south of I-264. This, along with the interchange reconfiguration is a major operational improvement, except for the fact the right lane will drop off going both directions to go under the bridge. That alone will likely cause a chokepoint as people have to merge down to 2 lanes, then to open right back to 6-lanes. Keeping it consistent at 6-lanes is the best way to go if it can be done. One way to accommodate this may be to reduce the lanes to 11 feet which is acceptable on an arterial roadway.

[Beltway]

then it gets into how even with 3 lanes there might not be much of an increase in capacity.

Of course it helps to snip what I had to say about the width available.

As with the Military Highway situation, there will be a minimum of 12 inches between the edge line and the concrete wall, that is a basic minimum so that you don't have a concrete wall at the very edge of the roadway and sheet metal.

So that would be 10.5 foot lanes southbound and 10 foot lanes northbound.  That would be narrow enough to cause considerable per lane capacity losses, and enough to throw the issue into question as to widening to 3 lanes each way but not replacing the bridge with longer spans.

I would need to see professional detailed traffic engineering analysis.

On Witchduck Rd or Military Highway?
If you're referring to Witchduck Rd, then I would disagree. That road is a major bottleneck, and all of it is being widened to 6-lanes north of I-264, and was recently widened to 6-lanes south of I-264. This, along with the interchange reconfiguration is a major operational improvement, except for the fact the right lane will drop off going both directions to go under the bridge. That alone will likely cause a chokepoint as people have to merge down to 2 lanes, then to open right back to 6-lanes. Keeping it consistent at 6-lanes is the best way to go if it can be done. One way to accommodate this may be to reduce the lanes to 11 feet which is acceptable on an arterial roadway.

[Alps]

then it gets into how even with 3 lanes there might not be much of an increase in capacity.

Of course it helps to snip what I had to say about the width available.

As with the Military Highway situation, there will be a minimum of 12 inches between the edge line and the concrete wall, that is a basic minimum so that you don't have a concrete wall at the very edge of the roadway and sheet metal.

So that would be 10.5 foot lanes southbound and 10 foot lanes northbound.  That would be narrow enough to cause considerable per lane capacity losses, and enough to throw the issue into question as to widening to 3 lanes each way but not replacing the bridge with longer spans.

I would need to see professional detailed traffic engineering analysis.

On Witchduck Rd or Military Highway?
If you're referring to Witchduck Rd, then I would disagree. That road is a major bottleneck, and all of it is being widened to 6-lanes north of I-264, and was recently widened to 6-lanes south of I-264. This, along with the interchange reconfiguration is a major operational improvement, except for the fact the right lane will drop off going both directions to go under the bridge. That alone will likely cause a chokepoint as people have to merge down to 2 lanes, then to open right back to 6-lanes. Keeping it consistent at 6-lanes is the best way to go if it can be done. One way to accommodate this may be to reduce the lanes to 11 feet which is acceptable on an arterial roadway.

Here is your analysis:
10' lanes have up to an 18% capacity reduction from 12' lanes.
3x 82 = 246
Therefore there would be a 23% capacity improvement over 2 lanes

[Beltway]

As with the Military Highway situation, there will be a minimum of 12 inches between the edge line and the concrete wall, that is a basic minimum so that you don't have a concrete wall at the very edge of the roadway and sheet metal.
So that would be 10.5 foot lanes southbound and 10 foot lanes northbound.  That would be narrow enough to cause considerable per lane capacity losses, and enough to throw the issue into question as to widening to 3 lanes each way but not replacing the bridge with longer spans.

Here is your analysis:
10' lanes have up to an 18% capacity reduction from 12' lanes.
3x 82 = 246
Therefore there would be a 23% capacity improvement over 2 lanes

Instead of 50%.

What about the capacity effect of having no shoulders, and concrete walls no more than 12 inches from each edge of the roadway?  How would that impact the figure?

[Alps]

As with the Military Highway situation, there will be a minimum of 12 inches between the edge line and the concrete wall, that is a basic minimum so that you don't have a concrete wall at the very edge of the roadway and sheet metal.
So that would be 10.5 foot lanes southbound and 10 foot lanes northbound.  That would be narrow enough to cause considerable per lane capacity losses, and enough to throw the issue into question as to widening to 3 lanes each way but not replacing the bridge with longer spans.

Here is your analysis:
10' lanes have up to an 18% capacity reduction from 12' lanes.
3x 82 = 246
Therefore there would be a 23% capacity improvement over 2 lanes

Instead of 50%.

What about the capacity effect of having no shoulders, and concrete walls no more than 12 inches from each edge of the roadway?  How would that impact the figure?

For such a short distance, negligible, especially because it's a permanent condition.

[Beltway]

Here is your analysis:
10' lanes have up to an 18% capacity reduction from 12' lanes.
3x 82 = 246
Therefore there would be a 23% capacity improvement over 2 lanes

Instead of 50%.  What about the capacity effect of having no shoulders, and concrete walls no more than 12 inches from each edge of the roadway?  How would that impact the figure?

For such a short distance, negligible, especially because it's a permanent condition.

Interesting.  So the agency would have to decide whether adding 50% more lanes but just obtaining 23% more capacity would be an effective use of resources.  That segment of the road would still have that much lower capacity than the rest of the road.

There would be benefits, but they could get the full 50% if they replaced the bridge, which would have its own resource costs.

[sprjus4]

Here is your analysis:
10' lanes have up to an 18% capacity reduction from 12' lanes.
3x 82 = 246
Therefore there would be a 23% capacity improvement over 2 lanes

Instead of 50%.  What about the capacity effect of having no shoulders, and concrete walls no more than 12 inches from each edge of the roadway?  How would that impact the figure?

For such a short distance, negligible, especially because it's a permanent condition.

Interesting.  So the agency would have to decide whether adding 50% more lanes but just obtaining 23% more capacity would be an effective use of resources.  That segment of the road would still have that much lower capacity than the rest of the road.

There would be benefits, but they could get the full 50% if they replaced the bridge, which would have its own resource costs.

Striping three lanes through there now and adding crash barriers could be a low-cost temporary relief for now, then in the long term could do a larger project to fully replace the bridge.

[Beltway]

So the agency would have to decide whether adding 50% more lanes but just obtaining 23% more capacity would be an effective use of resources.  That segment of the road would still have that much lower capacity than the rest of the road.
There would be benefits, but they could get the full 50% if they replaced the bridge, which would have its own resource costs.

Striping three lanes through there now and adding crash barriers could be a low-cost temporary relief for now, then in the long term could do a larger project to fully replace the bridge.

It would take more than striping, it would take widening the pavement.

[sprjus4]

So the agency would have to decide whether adding 50% more lanes but just obtaining 23% more capacity would be an effective use of resources.  That segment of the road would still have that much lower capacity than the rest of the road.
There would be benefits, but they could get the full 50% if they replaced the bridge, which would have its own resource costs.

Striping three lanes through there now and adding crash barriers could be a low-cost temporary relief for now, then in the long term could do a larger project to fully replace the bridge.

It would take more than striping, it would take widening the pavement.

That's practically nothing compared to constructing a 12-lane overpass with full shoulders, then having to build it without significantly impacting traffic.

You're talking $5 - $15 million compared to at least $100 million.

[Beltway]

It would take more than striping, it would take widening the pavement.

That's practically nothing compared to constructing a 12-lane overpass with full shoulders, then having to build it without significantly impacting traffic.
You're talking $5 - $15 million compared to at least $100 million.

It wouldn't cost $100 million to replace the bridge.

[sprjus4]

It would take more than striping, it would take widening the pavement.

That's practically nothing compared to constructing a 12-lane overpass with full shoulders, then having to build it without significantly impacting traffic.
You're talking $5 - $15 million compared to at least $100 million.

It wouldn't cost $100 million to replace the bridge.

At least $50 million or more. It's a 12-lane bridge, and the new one would have full shoulders more than likely. Then there's the issue with building it without significantly impacting traffic in the narrow footprint.

[Beltway]

At least $50 million or more. It's a 12-lane bridge, and the new one would have full shoulders more than likely. Then there's the issue with building it without significantly impacting traffic in the narrow footprint.

Where do you get all these cost estimates from?

The current bridge is 154 feet wide and 188 feet long, and has 4 spans.  The new bridge could be considerably shorter and have one long span over Witchduck Road underneath.  The abutments could utilize MSE walls, which are a lot cheaper than the days when that would be a massive reinforced concrete backwall from ground to bridge level.  See the new bridges on I-64 over Nine Mile Road in Henrico County, they were made considerably shorter with a similar situation to the above.

[plain]

Then there's the issue with building it without significantly impacting traffic in the narrow footprint.

Agreed with this. This construction would certainly create horrible backups on both roads, and I believe the backups will spill over well onto I-64.

[Beltway]

Then there's the issue with building it without significantly impacting traffic in the narrow footprint.

Agreed with this. This construction would certainly create horrible backups on both roads, and I believe the backups will spill over well onto I-64.

Wouldn't have to.  I have worked in road design, and I could design a maintenance of traffic scheme that would keep the current number of lanes open at all times.

[Alps]

At least $50 million or more. It's a 12-lane bridge, and the new one would have full shoulders more than likely. Then there's the issue with building it without significantly impacting traffic in the narrow footprint.

Where do you get all these cost estimates from?

The current bridge is 154 feet wide and 188 feet long, and has 4 spans.  The new bridge could be considerably shorter and have one long span over Witchduck Road underneath.  The abutments could utilize MSE walls, which are a lot cheaper than the days when that would be a massive reinforced concrete backwall from ground to bridge level.  See the new bridges on I-64 over Nine Mile Road in Henrico County, they were made considerably shorter with a similar situation to the above.

You're questioning the cost estimate, so show us a comparable project in a comparable area that's cheaper.

[Beltway]

At least $50 million or more. It's a 12-lane bridge, and the new one would have full shoulders more than likely. Then there's the issue with building it without significantly impacting traffic in the narrow footprint.

Where do you get all these cost estimates from?
The current bridge is 154 feet wide and 188 feet long, and has 4 spans.  The new bridge could be considerably shorter and have one long span over Witchduck Road underneath.  The abutments could utilize MSE walls, which are a lot cheaper than the days when that would be a massive reinforced concrete backwall from ground to bridge level.  See the new bridges on I-64 over Nine Mile Road in Henrico County, they were made considerably shorter with a similar situation to the above.

You're questioning the cost estimate, so show us a comparable project in a comparable area that's cheaper.

What "cost estimate"?  He largely grabs numbers out of the air.

[Alps]

At least $50 million or more. It's a 12-lane bridge, and the new one would have full shoulders more than likely. Then there's the issue with building it without significantly impacting traffic in the narrow footprint.

Where do you get all these cost estimates from?
The current bridge is 154 feet wide and 188 feet long, and has 4 spans.  The new bridge could be considerably shorter and have one long span over Witchduck Road underneath.  The abutments could utilize MSE walls, which are a lot cheaper than the days when that would be a massive reinforced concrete backwall from ground to bridge level.  See the new bridges on I-64 over Nine Mile Road in Henrico County, they were made considerably shorter with a similar situation to the above.

You're questioning the cost estimate, so show us a comparable project in a comparable area that's cheaper.

What "cost estimate"?  He largely grabs numbers out of the air.

Okay, but you haven't even grabbed any numbers at all, so he's winning.

[Beltway]

At least $50 million or more. It's a 12-lane bridge, and the new one would have full shoulders more than likely. Then there's the issue with building it without significantly impacting traffic in the narrow footprint.

Where do you get all these cost estimates from?
The current bridge is 154 feet wide and 188 feet long, and has 4 spans.  The new bridge could be considerably shorter and have one long span over Witchduck Road underneath.  The abutments could utilize MSE walls, which are a lot cheaper than the days when that would be a massive reinforced concrete backwall from ground to bridge level.  See the new bridges on I-64 over Nine Mile Road in Henrico County, they were made considerably shorter with a similar situation to the above.

You're questioning the cost estimate, so show us a comparable project in a comparable area that's cheaper.

What "cost estimate"?  He largely grabs numbers out of the air.

Okay, but you haven't even grabbed any numbers at all, so he's winning.

OK, it will be $1 billion.

See how easy that is?

[sprjus4]

At least $50 million or more. It's a 12-lane bridge, and the new one would have full shoulders more than likely. Then there's the issue with building it without significantly impacting traffic in the narrow footprint.

Where do you get all these cost estimates from?
The current bridge is 154 feet wide and 188 feet long, and has 4 spans.  The new bridge could be considerably shorter and have one long span over Witchduck Road underneath.  The abutments could utilize MSE walls, which are a lot cheaper than the days when that would be a massive reinforced concrete backwall from ground to bridge level.  See the new bridges on I-64 over Nine Mile Road in Henrico County, they were made considerably shorter with a similar situation to the above.

You're questioning the cost estimate, so show us a comparable project in a comparable area that's cheaper.

What "cost estimate"?  He largely grabs numbers out of the air.

Okay, but you haven't even grabbed any numbers at all, so he's winning.

OK, it will be $1 billion.

See how easy that is?

You've refuted and questioned numerous of times when transportation agencies, even VDOT, have released cost estimates that don't match what you think they should be.

[Beltway]

At least $50 million or more. It's a 12-lane bridge, and the new one would have full shoulders more than likely. Then there's the issue with building it without significantly impacting traffic in the narrow footprint.

Where do you get all these cost estimates from?
The current bridge is 154 feet wide and 188 feet long, and has 4 spans.  The new bridge could be considerably shorter and have one long span over Witchduck Road underneath.  The abutments could utilize MSE walls, which are a lot cheaper than the days when that would be a massive reinforced concrete backwall from ground to bridge level.  See the new bridges on I-64 over Nine Mile Road in Henrico County, they were made considerably shorter with a similar situation to the above.

You're questioning the cost estimate, so show us a comparable project in a comparable area that's cheaper.

What "cost estimate"?  He largely grabs numbers out of the air.

Okay, but you haven't even grabbed any numbers at all, so he's winning.

OK, it will be $1 billion.  See how easy that is?

You've refuted and questioned numerous of times when transportation agencies, even VDOT, have released cost estimates that don't match what you think they should be.

You and your buddy seem to think that it is my job to prove your $50 million and $100 million figures wrong.

[sprjus4]

You and your buddy seem to think that it is my job to prove your $50 million and $100 million figures wrong.

It wouldn't cost $100 million to replace the bridge.

You're the one who refuted the figure, so reasonably you should backup your argument with evidence to support it. The only thing you offered was a rural bridge replacement project in Richmond that was only two 3-lane bridges with no connecting interchanges. If you had brought up some major 10 - 14 lane bridge was recently replaced on some urban interstate in Virginia and it cost only $30 million, that would be reasonable. I suggested a $50 - $100 million generalized estimate based on the situation, a 12-lane interstate highway bridge in an urban area on a major route with limited room around it, and in today's day and age, nearby bridge projects seem to have high costs. These days a rural 2-lane overpass and connecting ramps will cost up to $15 - $20 million in Virginia, I'd say my estimate for a 12-lane urban interstate highway overpass is reasonable.

I'm not saying you're in the wrong for refuting the guesstimated figure, but refuting it without providing any counter argument and explanation doesn't give your comment much weight.