London Mayor proposes roadway tunnels to divert surface motor vehicle traffic and congestion
According to the Guardian ("Boris Johnson unveils road tunnel plans to ease London congestion"). From the article:
“Around eight of every 10 journeys in London are made using our roads – whether by car, taxi, motorbike, bus, cycle, foot or freight – which is why it is vital that we think big. We must deliver long-term solutions that will not just make the most of the space we have for road users but bring environmental and amenity improvemhistents to local areas.” ...Who knew that there is the International Tunneling and Underground Space Association?
He added: “By pushing forward strategic initiatives we are outlining today, we will lay the foundation for the next wave of improvements to everyone’s experience of the road network across the city.”
The major road tunnels are based on the strategies pursued in Stockholm and Boston, although the latter’s “Big Dig” proved difficult, costly and controversial. The success of flyunders in transforming parts of cities such as Madrid, where its inner ring road was partially buried, may make the smaller projects more viable. TfL believes a 1.3km tunnel at Barking could create a new neighbourhood of 5,000 homes in a blighted area, and that either tolls or the housing could make the project pay for itself.
-- "Urban Road Tunnels," ITA
-- "MADRID CALLE 30: AN URBAN TRANSFORMATION PROJECT"
I mention this because I have suggested this in the North Capitol-Blair Road corridor in DC, and support it for through traffic on New York Avenue (the equivalent of a connection between I-95 through DC to Virginia)--this is not my idea originally, it was suggested in the New York Avenue Transportation Study about ten years ago. 16th Street NW would be another corridor where this is worth considering.
The justification is that the negative impacts on abutting neighborhoods are significant and worthy of mitigation. The underground trip would be faster and therefore should be worthwhile for users, thereby justifying toll charges for the privilege. See "Tunnelized road projects for DC and the Carmel Tunnel, Haifa, Israel example--tolls."
I didn't know about the Madrid example. Marseille removed a highway along the waterfront by shifting it to an underused rail tunnel. Thessaloniki built a tunnel around its historic waterfront to divert surface/through traffic and create a more pedestrian-centric environment along the waterfront.
In Long Beach, an undergrounded rail tunnel, the Alameda Corridor, was built to facilitate freight movement between the port and the freight railway system.
It could have been interesting to have also built a tunnel for truck traffic between the port and the highway system, since the road system is inundated with truck traffic generated by the port.
Miami is creating such a facility, the N.W. 25th Street Viaduct Project, between the Miami Airport's cargo hub and the local freeway system (pictured at left).*
Of course, Boston's "Big Dig" or Central Artery Freeway is another example ("10 years later, did the Big Dig deliver?," Boston Globe) although it is not tolled.
Note that the tunnel underpasses in various places in the city, such as at Massachusetts Avenue and Thomas Circle for the roadway system and on North Capitol Street between M Street and Rhode Island Avenue, were early attempts to facilitate traffic movement but without providing simultaneous improvements in conditions for neighborhoods and the urban street fabric.
The Capitol Crossing development, which will deck over of the I-395 freeway between Masachusetts Avenue and D Street NE is an example of decking over an existing facility, without creating a new tunnel.
* Separately, I wonder if the Long Bridge reconstruction project--the bridge carries passenger railroad, freight railroad, and subway trains over the Potomac River between Southwest DC and Arlington County--should add lanes for a bi-directional dedicated busway.
It could serve National Airport when the subway is closed as well as tour bus traffic and other bus traffic to and from DC.