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Q: Slope of a block in Nob Hill, San Francisco, CA ( Answered 5 out of 5 stars,   6 Comments )
Question  
Subject: Slope of a block in Nob Hill, San Francisco, CA
Category: Miscellaneous
Asked by: rbnn-ga
List Price: $10.00
Posted: 17 Jul 2005 00:12 PDT
Expires: 16 Aug 2005 00:12 PDT
Question ID: 544421
What is the slope of California Street between Grant and Stockton in
San Francisco, CA?
Answer  
Subject: Re: Slope of a block in Nob Hill, San Francisco, CA
Answered By: tutuzdad-ga on 19 Jul 2005 09:36 PDT
Rated:5 out of 5 stars
 
Dear rbnn-ga;

Thank you for allowing me to answer your interesting question.

According to the Bureau of Street Use and Mapping, a division of the
City and County of San Francisco Department of Public Works, the
street grade (slope) of this portion of California Street between
Grant Avenue and Stockton Street is precisely 18.18%.

City of San Francisco Bureau of Street Use and Mapping
http://www.sfgov.org/site/sfdpw_index.asp?id=31968

I hope you find that my answer exceeds your expectations. If you have
any questions about my research please post a clarification request
prior to rating the answer. Otherwise I welcome your rating and your
final comments and I look forward to working with you again in the
near future. Thank you for bringing your question to us.

Best regards;
Tutuzdad-ga ? Google Answers Researcher



INFORMATION SOURCES

City of San Francisco Bureau of Street Use and Mapping
875 Stevenson Street, Room 460
San Francisco, CA 94103

Phone (415) 554-5810

SEARCH STRATEGY

Called City of San Francisco Bureau of Street Use and Mapping and made
personal inquiries.


SEARCH ENGINE USED:

Google ://www.google.com

Terms:

Bureau of Street Use and Mapping

Request for Answer Clarification by rbnn-ga on 19 Jul 2005 14:33 PDT
That's a great answer. I was wondering if you would be willing check
if there is a significant gradient differential within the block, as
suggested by the topographical maps cited in the comments by myoarin,
or if it's a constant gradient; if you have other detailed information
on elevations and so on that is helpful. I'll increase the price of
course if you find the extra info.

Clarification of Answer by tutuzdad-ga on 19 Jul 2005 15:46 PDT
Actually I only checked on the specific location you mentioned. I made
a long distance phone call to the Bureau of Street Use and Mapping and
was tranferred to a fellow who seemed to have ALL the information you
are talking about in a single neat software package. As a matter of
fact, he seemed to take great pride in how detailed his database was.
He made a few quick inquiries into his program and spit out the
information just as quickly. I'm sure if you give him a call he'd be
happy to produce the same set of data for you on jkust about any
location in San Francisco and perhaps even provide much more estensive
data to you directly via email.

Regards;
tutuzdad-ga

Clarification of Answer by tutuzdad-ga on 19 Jul 2005 15:48 PDT
PS:  If accuracy is an issue I wouldn't rely on a "suggested"
topographical formula that "might" be right when the actual surveys
are available free of charge (less the cost of the phone call of
course).

regards;
tutuzdad-ga
rbnn-ga rated this answer:5 out of 5 stars and gave an additional tip of: $3.00
Very helpful and researcher found a great source. I would have
preferred a bit more detail on the research process (the name of
person spoken to; the time and duration of call) as well as a bit more
on variability or lack thereof of the slope throughout the extent in
question. Also great comments.

Comments  
Subject: Re: Slope of a block in Nob Hill, San Francisco, CA
From: borisshah-ga on 17 Jul 2005 06:24 PDT
 
Hi There.

Would you like to know the gradient or the answer in degrees. Could
you please be more specific
Subject: Re: Slope of a block in Nob Hill, San Francisco, CA
From: myoarin-ga on 17 Jul 2005 06:31 PDT
 
As I reckon it from this map, that block of California St is 525 ft
long and rises approx. 75 ft.  By my calculation that would be a slope
of 14.3 %

http://www.topozone.com/map.asp?lat=37.7954&lon=-122.4019&size=s&symshow=n&datum=nad83&layer=DRG25

OK?

Myoarin
Subject: Re: Slope of a block in Nob Hill, San Francisco, CA
From: rbnn-ga on 17 Jul 2005 08:25 PDT
 
As to borisshah-ga's comment, the two measures are equivalent via arc-tangent.

As to myoarin-ga's comment, I am a bit skeptical of the accuracy or
precision of this map, at least as applied to such small distances.
For example the map shows the lower part of the block being about half
as steep as the middle part, which is not what I recall. Is there a
map at a finer scale, or information on the accuracy of this map?
Subject: Re: Slope of a block in Nob Hill, San Francisco, CA
From: myoarin-ga on 18 Jul 2005 06:16 PDT
 
Rbnn-ga,
I can't argue with you on that, but wouldn't we have to believe
something published by the US Govt?  (Don't answer that!)

Google Earth has a topographical feature, but my software doesn't accept it.
And I don't know it is more accurate.

This site - once you get into it -  seems to have the same topo-lines.

http://sunsite2.berkeley.edu:8088/xdlib//maps/brk00010.00000005.xml

I could not get to a map on the following one, but maybe you can.

http://gcmd.nasa.gov/records/SFB-Badger.html

This is a great map collection source, but I did not pursue it:

http://lii.org/search?searchtype=subject;query=Maps;subsearch=Maps

I wonder if all the modern topo maps have the same USGD source.
I could also imagine that slope of the streets has been straightened
over the years, something which has not been captured on the maps.

Good luck,
Myoarin
Subject: Re: Slope of a block in Nob Hill, San Francisco, CA
From: myoarin-ga on 19 Jul 2005 13:43 PDT
 
Yeah, that answer makes sense to me on the logic that my very rough
estimate of the distance between Grant Ave. and Stockton was too long,
especially considering that the slope of California St. is increased
by the fact that the sloping portion  is even shorter, starting to
drop a bit after the intersection at Stockton and leveling off before
the one at Grant.
I have to wonder a little at the Bureau's precision to the second decimal place.
If the distance between grant and Stockton is 425 ft, at a slope of
18.18% California rises 77.265 ft;  at a slope of 18.2%, it would rise
77.350 ft., just about one inch more.  Pretty fine measuring.
Subject: Re: Slope of a block in Nob Hill, San Francisco, CA
From: myoarin-ga on 22 Jul 2005 03:36 PDT
 
Rbnn-ga,
I agree entirely with your recollection and the information from
Tutuzdad-ga and the City that the sloping portion is now pretty much a
straight line, regardless of how the topography once was.  (Actually,
I was pretty pleased with my calculation, although it was proved
wrong.  I should have envisioned the street terrain instead of just
staring at the topo map and could have recognized that slope would be
greater.  Try me on Market St.)
Myoarin

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