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<< continued (page 2 of 2)
How much might a tunnel like this cost?
Difficult question: Since initial cost estimates of the Big Dig proved to
be off by a factor of four, who would trust anyone's estimate of this?
Still, if the tunnel costs $1 million per foot, then the whole thing might
cost over $17 billion. If the tunnel costs $1 million per yard the cost
would be over $5 billion. (One Big Dig final cost est. is $14.7 billion /
7.8 miles = $357,000/ ft., or about $1 million per yard.)
All tunnels are expensive, but computers & robotics are said to
have made the cost of deep-bore tunnels
plummet in the last decade - when bored in soft ground substrates like
Boston-blue-clay.
- Since it is only
for autos & light vehicles, the 6-mile long A86 West Tunnel has
a small (low-cost) diameter.
- Its 45 mph speed
limit further reduced its cost, since road & tunnel safety are
cheaper to build-in for low speeds.
- Since existing
traffic doesn't need to rerouted while a deep-bore-tunnel is under
construction, it is far less expensive to build: Only after a new
tunnel is completely done is traffic disrupted while the entrance
ramps from existing roadways to the new tunnel are built.
- One estimate from
the Big Dig has the cost set aside to keep existing interstates,
streets, and sidewalks open during construction at nearly $5
billion, or one-third of the Big Dig’s total
costs.
How much might the tunnel that Harvard is
proposing for Soldier's Field Road cost?
Another difficult question. Harvard currently has only preliminary
proposals, and certainly no cost estimates. It is too soon for Harvard
University to know what it may finally propose - but their most recent
planning report, issued June 2005 (prepared by the design firm Cooper
Robertson Inc. http://www.allston.harvard.edu/vision/CRP_Interim_Report_June_2005.pdf)
suggests a few tunnel possibilities, and may hint at others.
The only drawing in this report that shows depression of Soldier's Field
Road is a sketch of an option for new undergraduate housing in Allston,
near the Weeks Footbridge. Soldier's Field road is shown depressed from
the Anderson Bridge to the Western Avenue Bridge (figure 8 on page 18).
The one sketch shows about 2300 feet of Soldier's Field Road in a tunnel,
between North Harvard Street and Western Avenue. (This estimate of the
tunnel's length excludes the 200 ft entrance ramps shown at both ends of
the depressed section.) If the unit price for such a tunnel were $357,000
per linear foot, the total cost would be $821,000,000
without the entry ramps, and might be $964,000,000
inclusive of the new ramped sections at both ends. However, the report's
text includes references to more than one location for road depression.
An excerpt from the text follows:
"Better access to the river would be a
wonderful benefit to Allston and Cambridge residents and to the Harvard
community. Soldiers Field Road blocks access to the river, and as noted
earlier there are few crossings – the ones at Telford and Everett serve
the Allston community, and Everett allows vehicular access to the
amphitheater. Additional traffic lights could be installed between
Everett and the Eliot Bridge. A more major and costly intervention might
be to depress some parts of Soldiers Field Road. The obvious locations
are at Newell Boat House, if undergraduate houses are built near Dillon
Field House; or at the Weeks Bridge, especially if that becomes the
chosen route for a new river crossing. Thesepossibilities require further
exploration." (page 27)
If Harvard were to depress the entire 5300 feet of Soldier's Field
Road between the Eliot and Western Avenue Bridges, at a unit cost of
$357,000 per linear foot, the total cost would be about $1.9 billion. (This estimate again excludes entry
ramp lengths from the calculation.)
Further, it may be fair to infer from the above excerpt that Harvard
could eventually propose depressing Soldier's Field Road from Everett
Street to Western Avenue, particularly since it seems unlikely Harvard
would expect to receive public permission to depress only those parts of
Storrow Drive that would wonderfully benefit the Harvard community but
not as directly benefit Allston or Cambridge residents. If Harvard were
to eventually suggest depressing the 8200 feet of Soldier's Field Road
between Everett Street and Western Ave, again assuming a $357,000 per
linear foot unit price, the total cost would be $2.9
billion.
Since the June 2005 Cooper Robertson report only deals with a 20-year
planning horizon (page vii in
Appendix B) it does not include discussion of Harvard's property
to the south of Cambridge Street (the Mass Turnpike land and Conrail
freight yards) which will be developed at a later time. The report hints
at nothing about a possible full scope of Soldier’s Field Road/Storrow
Drive depression that Harvard might envision in the future. If Harvard
were eventually to suggest depressing Soldier's Field Road even further
east than the Western Avenue Bridge, the total cost might be as follows:
If Harvard suggests depressing the 12,350 feet of Soldier's Field Road
between Everett Street in Allston and Buick Street in Brighton (the first
side street west of the Boston University Bridge), again assuming a
$357,000 per linear foot unit price, the total cost would be $4.4 billion.
The above calculations suggest that tunnels of the kind proposed in
this website for elimination of river traffic along the Charles may be
more cost effective than those currently under consideration for the
Allston Initiative. Click on map below to
view larger size
A Utopian
Vision for Urban Expansion along the Charles River Basin
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