International firms propose splendid new FSK Bridge for Baltimore Harbor
The first detailed concept for replacing the Francis Scott Key Bridge has come from an impressive group of international designers, engineers, builders and architects -- Webuild Construction of Milan Italy, Carlo Ratti Assoc urban designers of Turin Italy and MIT Boston and bridge engineers Michel Virlogeux Consultants of Paris.
They propose a two-tower cable-stayed bridge with a main span of 2,297ft (700m) allowing the towers to be placed in shallow water well away from the main channel, and out of any possible path of errant container or cruise ships. The old through-truss bridge whose twisted steel ruins still obstruct shipping had a main span of only 1201ft (367m).
As we saw demonstrated most dramatically in the early hours of March 26 the 1977 bridge had at least one of its main piers located in water deep enough to accommodate even a large deep draft container ship!
The Webuild-Ratti-Virlogeux (WRV) team suggest the new bridge be built with 65m (213ft) clearance to allow the very largest ships into Baltimore Harbor. The old FSK truss bridge had overhead clearance of 56.4m(185ft).
And they propose it be built wider with provision for 3 lanes each direction and more generous breakdown shoulder lanes.
Comments
1. 3rd laning: the traffic at 34,000 vehicles/day (vpd) at the FSK Bridge doesn't get near to justifying a wider bridge than the old 2x2 12' lanes. The I-695 FSK crossing is too circuitous a route to attract long-distance traffic and the bridge here served mainly a local function, providing connections to Dundalk and Sparrows Point. Traffic isn't growing.
The only justification for 2x3 lanes I can think of is as a hedge against closure of one of the harbor tunnels. Average daily traffic normally has to be over 80,000vpd and growing to justify 2x3 lanes. On I-270 between Clarksburg and Federick traffic is 110,000vpd on 2x2 lanes and US15-thru-Frederick is similar. Third laning here around Frederick is a far higher priority than for the light 34,000vpd on the FSK Bridge.
2. Clearance: 213ft (65m) clearance could make sense if it were part of a program to raise all the Chesapeake Bay bridge spans. The two US50 William Preston Lane bridge spans have the same 185ft (56.5m) clearance as the now-deceased FSK Bridge, so without also raising those a higher FSK bridge would serve no purpose. At the mouth of the Bay is the Chesapeake Bay Bridge-Tunnel, the US Navy having vetoed any bridge over the shipping channel there as too tempting a target for an enemy wanting to bottle up half the US naval fleet in the port of Norfolk.
3. Aesthetics: To my eye the twin tower cable-stayed bridge is far better looking than the clunky truss bridge and would be a big plus for the Baltimore skyline. Elegant, beautiful. But then some people eye Mar-a-Largo's decorative extravagance or adding classical columns of PVC to the front of a single-story Bank of America and see beauty.
Practicality is the best argument for a longer span cable-stayed bridge, 2x2 lane plus 12’ rightside pull-off shoulders that could be 3rd lanes in emergencies.
REFERENCES
https://www.dezeen.com/2024/05/07/carlo-ratti-replacement-baltimore-bridge/
Webuild construction company based in Milan Italy https://www.webuildgroup.com/en/media/press-notes/webuild-ready-rebuild-baltimore-bridge-collapsed-march/
Carlos Ratti Associates, international design company based in Turin Italy https://carloratti.com
Carlos Ratti, MIT prof, celebrity urbanist, owner of CR Associates https://professional.mit.edu/programs/faculty-profiles/carlo-ratti
French bridge engineer https://www.michelvirlogeuxconsultant.com
These guys did the visualizations out of Budapest Hungary: https://brickvisual.com/#homestart (look out for a brilliant video fly-through of their offices)
PSam 20240507 edits 08