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[ixnay]

Spacing concerns with both construction and maintenance would likely preclude putting it in between.  There's a reason the existing westbound span was built as far from the original (current eastbound) span as it was.

I agree.  If a new span were to be built parallel to the existing two, it would need to go south of the "old" (1952) 2-lane span that normally runs eastbound only.  North of the "new" (1972) 3-lane span probably means unacceptable impacts on Sandy Point State Park. 

And there's at least some room south of the old span for a bridge landing on the western side of the crossing, by using the former area where the ferry had a slip prior to the opening of the "old" bridge.

The spans are about 450' apart (except where they taper together at the west end to accommodate the toll plaza and minimize impact on Sandy Point).

OTOH the spans of the Delaware Memorial Bridge are about 250' (dangerously close IMO).  They are that close to accommodate the DuPont Chambers Works and the Atlantic City Electric power station on the NJ side.

Pictures I've seen of the old cantilevered Sunshine Skyway spans in FL have them being even closer together than 250', but I haven't found out how close.

ixnay

[Alps]

Spacing concerns with both construction and maintenance would likely preclude putting it in between.  There's a reason the existing westbound span was built as far from the original (current eastbound) span as it was.

I agree.  If a new span were to be built parallel to the existing two, it would need to go south of the "old" (1952) 2-lane span that normally runs eastbound only.  North of the "new" (1972) 3-lane span probably means unacceptable impacts on Sandy Point State Park. 

And there's at least some room south of the old span for a bridge landing on the western side of the crossing, by using the former area where the ferry had a slip prior to the opening of the "old" bridge.

The spans are about 450' apart (except where they taper together at the west end to accommodate the toll plaza and minimize impact on Sandy Point).

OTOH the spans of the Delaware Memorial Bridge are about 250' (dangerously close IMO).  They are that close to accommodate the DuPont Chambers Works and the Atlantic City Electric power station on the NJ side.

Pictures I've seen of the old cantilevered Sunshine Skyway spans in FL have them being even closer together than 250', but I haven't found out how close.

ixnay

What about 250' is dangerous, IYO? The new K-Bridge spans in NY will be about 16' apart.

[Beltway]

Is it too obvious to put a new bridge in between the two existing ones?  The main spans are quite far apart.

They have been talking about this and studying the for at least 20 years, and nothing has been done or decided.

The ideal third bridge would be a 3-lane bridge about 200 to 300 feet south of the existing eastbound bridge.  That configuration would provide a 3-lane bridge each way, and the original 2-lane bridge would be in the middle and would be reversible to assist in the peak traffic direction. 

Approach roads would be widened some time in the future, maybe simply by adding a 2-lane reversible roadway between MD-2 and the US-50/US-301 split.

[Duke87]

Core capacity on Metro (even just the Orange and Silver Lines) is not just the part that crosses under the Potomac River.  That's something the local news media gets wrong over and over and over again.  Core capacity is from Rosslyn all the way to the wye on the elevated tracks east of Stadium/Armory near the D.C. 295/Benning Road, N.E. interchange.

Nitpick: what is on the elevated tracks east of Stadium/Armory is not a wye, as it does not allow direct movements from New Carrollton to Largo Town Center.

[Revive 755]

What about 250' is dangerous, IYO? The new K-Bridge spans in NY will be about 16' apart.

From a quick measurement in Google Earth, it appears the Tacoma Narrow twins are only ~125 feet apart.

[DeaconG]

Whatever happened to the Taylor's Island crossing proposal? Perhaps it should be revived?

[froggie]

^ It's a location that's still part of the study and got mentioned in the article posted the other day.  But has plenty of problems of its own.

[cpzilliacus]

^ It's a location that's still part of the study and got mentioned in the article posted the other day.  But has plenty of problems of its own.

I think it should be studied as part of a NEPA alternatives analysis.  But the Bay there  is roughly the same width as at Sandy Point (maybe slightly wider), and with approaches, it is over 9 miles from MD-2/MD-4 in Calvert County to MD-16 on Taylors Island (on the western side of Slaughter Creek).

A southern crossing also implies a lot of expensive improvements to many miles of MD-4 and maybe the MD-2 corridors north of any Calvert County landing of such a crossing.

It's also a considerable distance from a potential Dorchester County landing to U.S. 50 near Cambridge, at about 16 or 17 miles or more, following the path of MD-16. 

There are also Section 4(f) resources (parklands) on both sides of the Chesapeake Bay to avoid, and also the Cove Point LNG Terminal and the Calvert Cliffs nuclear power plant that have to be avoided too.

[Beltway]

[Southern Bay Crossing]
^ It's a location that's still part of the study and got mentioned in the article posted the other day.  But has plenty of problems of its own.

Cost issues for a 6-mile-long bridge plus about 20 miles of new approach roadways between MD-2 and US-50.

Environmental issues especially many wetlands between the bridge and US-50 near Cambridge.

Traffic issues as its position doesn't compete with the existing Bay Bridge for residents of
the northern part of the D.C. area and the Baltimore area, traveling to the ocean resorts.

[cpzilliacus]

Cost issues for a 6-mile-long bridge plus about 20 miles of new approach roadways.

Environmental issues especially many wetlands between the bridge and US-50 near Cambridge.

Traffic issues as its position doesn't compete with the existing Bay Bridge for residents of the northern part of the D.C. area and the Baltimore area, traveling to the ocean resorts.

The southern (or, more-correctly, mid-Bay) crossing is good in terms of establishing network redundancy, a good and desirable thing here, given that there are currently exactly two highways that link Maryland's Eastern Shore counties to the rest of the state.

Is it worth  the expense?  I don't know.  That's for the study to determine.

[Beltway]

Cost issues for a 6-mile-long bridge plus about 20 miles of new approach roadways.
Environmental issues especially many wetlands between the bridge and US-50 near Cambridge.
Traffic issues as its position doesn't compete with the existing Bay Bridge for residents of the northern part of the D.C. area and the Baltimore area, traveling to the ocean resorts.

The southern (or, more-correctly, mid-Bay) crossing is good in terms of establishing network redundancy, a good and desirable thing here, given that there are currently exactly two highways that link Maryland's Eastern Shore counties to the rest of the state.
Is it worth  the expense?  I don't know.  That's for the study to determine.

Southern bay crossing for Maryland.  The existing crossing is central and there is a not-built northern bay crossing that has been proposed and studied in the past.

It would provide good connectivity between southern Maryland and the lower Maryland Eastern Shore, as the current routing is rather circuitous.

I doubt that they can afford to build more than one new bay bridge, and by far the most effective place would be a third span of the current central crossing that is strategically placed to serve both the Baltimore and Washington areas, and connect the US-301 and US-50 arterial highway corridors on both sides of the Bay.

The northern crossing has similar limitations in the catchment area that it could serve.

I don't see the southern or northern crossings providing much traffic relief to the current bridges.

[jwolfer]

^ It's a location that's still part of the study and got mentioned in the article posted the other day.  But has plenty of problems of its own.

I think it should be studied as part of a NEPA alternatives analysis.  But the Bay there  is roughly the same width as at Sandy Point (maybe slightly wider), and with approaches, it is over 9 miles from MD-2/MD-4 in Calvert County to MD-16 on Taylors Island (on the western side of Slaughter Creek).

A southern crossing also implies a lot of expensive improvements to many miles of MD-4 and maybe the MD-2 corridors north of any Calvert County landing of such a crossing.

It's also a considerable distance from a potential Dorchester County landing to U.S. 50 near Cambridge, at about 16 or 17 miles or more, following the path of MD-16. 

There are also Section 4(f) resources (parklands) on both sides of the Chesapeake Bay to avoid, and also the Cove Point LNG Terminal and the Calvert Cliffs nuclear power plant that have to be avoided too.

My brother lives in Calvert County.. they very much want to keep the county rural( expensive exurbs now).   The county commission does not want the metro extended to Calvert County so I am sure they do not want a new crossing of the Bay

Z981

[cpzilliacus]

My brother lives in Calvert County.. they very much want to keep the county rural( expensive exurbs now).   The county commission does not want the metro extended to Calvert County so I am sure they do not want a new crossing of the Bay

I am quite familiar with  Calvert County.  There used to be anti-development bumper stickers that read "Keep Calvert Country!" that were pretty common.   

Have not seen one for a while.  Maybe because much of northern Calvert County (along MD-4) is now exurban sprawl of Washington and to a lesser extent Baltimore (because it's a long trip from anywhere in Calvert County to most employment in the Baltimore region). 

Remember also that Maryland allows its county governments significant authority to regulate land use. That's one of the reasons why there are several interchanges along busy freeways in the state with no gas stations or convenience stores or other retail nearby.  In some counties, the elected members of the Board of Commissioners or County Councils choose not to use that authority, but in some counties, the regulation is quite  strict.

Southern Calvert County has become a "suburb" of residential development for employment to the south in St. Mary's County, where Lexington Park has grown significantly thanks to BRAC (base realignment and closure) rounds, with many jobs related to the Defense Department ending up at Naval Air Station Patuxent River, including the Naval Air Systems Command.  EDIT:  There has been enough population growth in southern Calvert County, and across the Patuxent River in St. Mary's County, that a metropolitan planning organization has been formed called (quite simply) the Calvert-St. Mary's Metropolitan Planning Organization.

[Beltway]

Southern Calvert County has become a "suburb" of residential development for employment to the south in St. Mary's County, where Lexington Park has grown significantly thanks to BRAC (base realignment and closure) rounds, with many jobs related to the Defense Department ending up at Naval Air Station Patuxent River, including the Naval Air Systems Command.  EDIT:  There has been enough population growth in southern Calvert County, and across the Patuxent River in St. Mary's County, that a metropolitan planning organization has been formed called (quite simply) the Calvert-St. Mary's Metropolitan Planning Organization.

Also are trying to find the funding to build a parallel MD-4 Thomas Johnson Bridge, due to severe traffic congestion.
....

Excerpts:

Study to upgrade MD 4 between MD 2 and MD 235 (4.0 miles), including the Governor Thomas Johnson Memorial Bridge (Bridge 04019) over the Patuxent River and the intersection at MD 235 (2.9 miles).

Currently, the Thomas Johnson Bridge is funded for final design, only. Funding for design, right of way, acquisition and construction for the other project phases will proceed as funds become available.

The Maryland State Highway Administration (SHA), secured Federal Highway Administration (FHWA) Location Approval of SHA’s “Selected Alternative” on September 10, 2015

A new four-lane parallel bridge would be built with two northbound and two southbound lanes.

http://apps.roads.maryland.gov/webprojectlifecycle/ProjectInformation.aspx?projectno=SM351114
....

Question:  What happens to the existing bridge?

[ixnay]

What about 250' is dangerous, IYO? The new K-Bridge spans in NY will be about 16' apart.

What if one of the DMB towers topples towards the other?  Picture that scenario (smacks of Armageddon I know, but...).

ixnay

[ixnay]

What about 250' is dangerous, IYO? The new K-Bridge spans in NY will be about 16' apart.

From a quick measurement in Google Earth, it appears the Tacoma Narrow twins are only ~125 feet apart.

Well, I'm not an engineer nor do I play one (or anyone) on TV, but what's there at the Tacoma Narrows landings prevented the spans from being built farther apart?

ixnay

[Alps]

What about 250' is dangerous, IYO? The new K-Bridge spans in NY will be about 16' apart.

What if one of the DMB towers topples towards the other?  Picture that scenario (smacks of Armageddon I know, but...).

ixnay

That is not going to happen. That is not the failure mode of a bridge. If something happens to one of the piers, the weight of the bridge will collapse downward. It really cannot topple outward like you're picturing.

[1995hoo]

What about 250' is dangerous, IYO? The new K-Bridge spans in NY will be about 16' apart.

What if one of the DMB towers topples towards the other?  Picture that scenario (smacks of Armageddon I know, but...).

ixnay

Given the pop-culture meaning of "DMB" in reference to a band from Charlottesville, I now have this unfortunate mental image of one of the two bridges singing to the other to "Crash into Me" ..... 

[davewiecking]

https://wtop.com/dc-transit/2018/08/summer-traffic-backups-toward-bay-bridge-could-worsen/

WASHINGTON — Drivers headed to the Eastern Shore on U.S. Route 50 were caught in long backups last Friday, and many were further aggravated when they discovered only two lanes were open to eastbound traffic at the Bay Bridge. It turns out the traffic pattern was no mistake, and it could become the new norm.
...
Last Friday, beach-bound families, commercial drivers and residents alike were blindsided by a backup that extended from near Interstate 97 to the Bay Bridge, a distance of greater than 10 miles. Unlike most partly sunny, summer Friday afternoons, the reversible lane remained devoted to westbound traffic, limiting eastbound drivers to two lanes across the Chesapeake Bay.
...
Although westbound traffic was at a free flow for hours before two-way traffic was put into effect, a spokesperson for the Maryland Transportation Authority said the agency will be prioritizing westbound traffic, keeping the reversible lane open to westbound drivers longer, even on summer Fridays.

The MDTA said police and fire departments and other rescue personnel east of the Bay Bridge in Queen Anne’s County have said that when westbound traffic on Route 50 backs up, bailout traffic floods the limited routes across Kent Island, thus hampering rescue operations.

Trip last Friday took me an extra hour. Side roads paralleling US-50 on the "mainland" side of the bridge were pretty packed, thus hampering any potential rescue operations. The conspiracy theorist in the room believes this is part of the push to build a third Bay crossing.

[Beltway]

Trip last Friday took me an extra hour. Side roads paralleling US-50 on the "mainland" side of the bridge were pretty packed, thus hampering any potential rescue operations. The conspiracy theorist in the room believes this is part of the push to build a third Bay crossing.

The frontage roads and MD-18 have about 1/10 the capacity of a 6-lane freeway, and they have signals and at-grade intersections which further slow traffic and reduce capacity.

[TheOneKEA]

It may be into fictional highway territory, but I’m of the opinion that the 2-lane bridge needs to be replaced with a 6-lane bridge with full shoulders someday, and the 3-lane bridge repurposed for local and/or emergency traffic.I strongly doubt that a Northern or Southern crossing of any sort will ever be built.

[cpzilliacus]

It may be into fictional highway territory, but I’m of the opinion that the 2-lane bridge needs to be replaced with a 6-lane bridge with full shoulders someday, and the 3-lane bridge repurposed for local and/or emergency traffic.I strongly doubt that a Northern or Southern crossing of any sort will ever be built.

Problem is that both of the existing spans have plenty of useful life left, making it unlikely that MDTA would agree to remove even the original 1952 span (which will need to have its deck replaced in the coming years but is still in overall good condition).

[jeffandnicole]

It may be into fictional highway territory, but I’m of the opinion that the 2-lane bridge needs to be replaced with a 6-lane bridge with full shoulders someday, and the 3-lane bridge repurposed for local and/or emergency traffic.I strongly doubt that a Northern or Southern crossing of any sort will ever be built.

They could always build a new 3 lane span, use the two, 3 lane spans for 50/301 traffic, and bridge the roadway for the 2 lane span over/under one of the roadways approaching a 3 lane span for local traffic.

[Mr_Northside]

I'm not sure that I'm into (not that it really matters what I think) the notion of a span for "local traffic".  Even with the current bridges, I can't imagine that on a "local level", either side has much to do with each other.

I'm pretty sure I've opined on this before (possibly in a different thread), but it seems that as much as just having 5 lanes (total) capacity, the fact that neither span has really any shoulders to speak of is a major problem.  The bridge can be intimidating enough to some just due it it's nature, but when you're right against the barrier, I think it causes a lot more slow driving than if there was more space between the lanes and the sides of the bridge.

My thoughts are to just build a 3 lane span that actually has full left/right shoulders and used for the direction of travel that makes sense for whether it gets built north or south of the existing spans - Then convert the original 2-lane span to a 1 lane span with shoulders, and the existing 3 lane to 2 lanes with shoulders for the other direction of travel.

That said.... I'll be mostly surprised (but not totally shocked) if a new span gets built across the bay anywhere before I die.

[Beltway]

There is plenty of local traffic between the Annapolis area and Kent Island, and Baltimore and D.C. area commuters from Kent Island.

I don't know of any bridge in the world of that nature (function of length and height) that has a 10-foot right shoulder.  Deck space on a bridge like that is extremely expensive to build.