vertical accessquarterly  Industry news and perspective from Vertical Access LLC    Volume 1, Issue 5, December, 2004

helping architects and engineers deliver superior design documents  


In this issue...

St. Patrick's Cathedral

Technical Highlight: Radio Frequency Safety

TPAS Development

St. Thomas Update

VA in the News


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St. Patrick's Cathedral

st. patricks cathedral in new yorkBy the turn of the century, the swelling Catholic community in New York City had outgrown St. Peter's Church - the center of the Catholic Diocese in New York at the time.  Plans were drawn for a new Cathedral to be built at Mott, Mulberry and Prince Streets, then considered to be "in the suburbs of the city".

Construction began in 1809 and, at the time of the dedication in May of 1815 the old Cathedral stood as the largest religious edifice in New York City.  For 57 years the structure stood as the center of Catholic faith, until tragedy struck. On October 6, 1866,  fire ravaged the Cathedral.  Amazingly, the four walls survived the fire and the Cathedral was rebuilt in 2 years: the rededication took place in 1868.

A search by the trustees for a new expanded burial ground in 1810 led them to purchase the present site of the new St. Patrick's Cathedral for a mere $20,000, after improvements.  In 1850, Archbishop Hughes decided that a new monumental Cathedral was to be built on the site, with most of the planning meetings taking place at the old Cathedral.  In the following excerpt from architect James Renwick's original report, he presents the different possibilities for building stone:

"Our opinion is therefore decided that there is no material which combines the three essentials of durability, beauty, and economy as well as white marble.  As regards to comparative expense of the whole building in the three materials, contractors estimate that the Cathedral will cost:

In White Marble         $830,000
In Albert Stone          $800,000
In Belleville Stone      $805,000
In Dorchester Stone   $830,000

From the above it will be seen that the building will cost $50,000 more than in the free stone.  Our opinion is that the beauty and durability of the former material would more than justify this additional expense, an our belief is that if constructed of this beautiful material it will be worthy of the noble purpose to which is will be dedicated as the work of man's hands can be."

rope access workers on the cathedral spireRenwick's argument for the white marble prevailed and the Cathedral was designed and decorated in the gothic style, reminiscent of the Cathedrals of Rheims, Amiens and Cologne. 

The first cornerstone on the new center of the Archdiocese was placed in 1858 and construction of the cathedral as it stands today continued through 1931.  The cathedral is clad with at least three different types of marble:  the 330' spires and towers are clad mostly in marble from Cockeysville, MD, lower portions of the nave and tower, including the Fifth Avenue facade are clad in Tuckahoe (or Pleasantville, NY) marble, and some of the more recently replaced decorative elements on the Fifth Avenue facade are carved from Lee (Massachusetts) marble.  

The Cathedral was opened formally on May 25, 1879 - thirty-five bishops and six Archbishops were present to honor the blessing by Cardinal McCloskey.  

Fighting the crowds on Fifth Avenue in front of St. Patrick's Cathedral today it is hard to believe that when Archbishop John Hughes first presented the idea of a new St. Patrick's Cathedral in 1853 he had to fight public opinion that the new center of the Archdiocese was too far out of town.  The Cathedral's midtown location is now a prime tourist attraction.  

From October 25 - 28, 2004 Vertical Access technicians Kent Diebolt, Mike Gilbert, Tom Zajicek, Stardust Atkeson and Kelly Streeter acquired photographic and noted documentation of the condition of the Cathedral.  The inspection was undertaken to investigate and document existing conditions of the four facets on each of the north and south towers and spires, and the west facade of the Fifth Avenue gable end.  A secondary purpose of the survey was to assist others in the development of construction estimates, budget and work phasing plans, and, if necessary construction documents leading up to a cyclic repair campaign.  The previous exterior repair campaign completed in the late 1970's by Nicholson and Galloway was completed with the utmost care.  

Mike Gilbert annotated his drawings directly in AutoCAD using the Tablet PC Annotation System (TPAS).  To learn more about the history of the development of the TPAS system, go to  For information about and the TPAS system, see the article on TPAS, below.  -Kelly Streeter, Photos by Jon Reis


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Technical Highlight: Radio Frequency Safety

RF symbol
RF Symbol used wherever 
overexposure to RF or MW 
radiation is possible

Architects and Engineers who routinely find themselves clambering around buildings are often unaware of a possible silent danger.  With the explosion of technology over the last several years, antennas, sprouting up in unlikely places, are a potentially dangerous source of radio frequency (RF) and microwave (MW) radiation.  Whereas workers who service this equipment undergo training and wear protective gear, architects and engineers might be exposed unwittingly.

In general, humans are not in grave danger of high radiation exposure unless they are near a device and then the level of exposure is greatly dependent on the type and path of the directed energy.  The primary health effect of RF/MW energy results from the heating up of human tissue - the extent of this heating is related to the absorption which varies with the frequency of the energy.  Microwave energy (higher frequency) is not absorbed deeply into tissue - so the main concern is "near surface" effects - those close to the skin.  Whereas RF (lower frequency) energy penetrates more deeply and can affect organs.  

The following table offers a guideline for antenna safety:

Antenna Type Description Danger Photo
Cellular: radio Cellular antennas are split into two basic types, the first being the cellular radio service, which operated at frequencies about 800-900 MHz.   In both the cellular and PCS cases, an individual would have to stand in the the main transmitting beam within a few feet of the antenna in order to be exposed to levels at or near the FCC limits for exposure.


Cellular: PCS he PCS antennas come in two main forms: omni-directional and sector.  The omni directional antennas are 10-15' poles where the sector antennas (which are more commonly used in urban areas are approximately 1' x 4' rectangular antennas In both the cellular and PCS cases, an individual would have to stand in the the main transmitting beam within a few feet of the antenna in order to be exposed to levels at or near the FCC limits for exposure.

PCS omni

PCS sector


Microwave Microwave or "point-to-point" antennas transmit and receive microwave signals across short distances (.5 - 30+ miles).  They transmit directly from transmitting to receiving antennas and the exposure limits outside of this relatively narrow beam is minimal to insignificant. Significant exposures from these antennas could only occur in the unlikely event that an individual were to stand directly in front of and very close to an antenna for a period of time.

microwave point to point

Satellite-Earth Satellite to Earth antennas are pointed (of course) up to the sky to receiving and redirecting satellites.  Because of the distances involved, the power levels are very large when compared to microwave point-to-point antennas. This energy is also very directional and therefore would not pose a problem unless a worker were to stand in the narrow path for some period of time.  


Whenever it is apparent that exposure to RF/MW radiation is a possibility, workers should wear radiation monitors, which can note the type (frequency) and level of energy encountered.  Most of these monitors allow the user to preset threshold levels and an alarm will sound if that threshold is exceeded. -Kelly Streeter

Relevant links:

A sobering story:
1998 AIHA abstract:
OSHA info:

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TPAS: Tablet PC Annotation System

old design documentsStarting in 1997, Vertical Access began incorporating hand-written field notes into AutoCAD attribute tags or data blocks. These attribute tags are database records contained in the CAD file that appear as graphics on the drawing but, as distinguished from mere notes on paper, may be exported to a spreadsheet for sorting, tallying and for use as variables in estimating equations. At that time, this was a two-step process: First, one would take notes on paper in the field and then enter the notes as attribute tags in AutoCAD in the office while re-drafting the final graphical portion of the project deliverables.

In 2001, Vertical Access began using hand-held, pen-based computers running under Windows CE with a CAD program capable of producing .dwg-compatible files for collecting data in the field. At that time, we were asked to document contractor-inflicted damage to a U.S. government building in Newark, NJ. Our charge was to locate and document every nick and over-cut mortar joint on the building. Notes were made on over 3000 conditions, with a photo supporting each observation.

Instead of draw-down menus, a system based on the full version of AutoCAD running on a tablet computer would mean using libraries of data blocks or attribute tags, rather than pull-down menus. AutoCAD's "Design Center" allows easy access to the various data blocks. This approach has been developed by Mike Gilbert in our office and employs only the native capabilities of AutoCAD 2002, right "out of the box".  

Placing the data block icon on the drawing calls up a prompt to enter the dimensions or extent of the fault. Photo ID numbers are also entered here if applicable. It is possible to calculate and enter the area (square feet) and length (linear feet) of a fault location and assign this information to the attribute tag.  Vertical Access is currently working on developing programming for automatic length and area calculations and photo linking capabilities.

Mike has pared-down the tool pallet to only the essential functions leaving the AutoCAD screen less cluttered and simpler to use in the field.

Building different "views" and switching layers off and on allows for interpretation of the graphical data and analysis of patterns of deterioration. This system makes GIS-like queries and analysis possible.

Using the old method of collecting, managing and presenting data, with PocketCAD and ESA, the final product might contain a very dense amount of information. Larger, complex buildings with numerous materials and fault types require multiple plots per elevation to clearly portray conditions found. Currently, Vertical Access is looking into different ways to portray the graphical data contained in our reports in order to increase the utility of our project deliverables.

The "after" elevation shown contains all of the graphical and numerical information in the tags and leaders on the "before" elevation. We feel that this is a much clearer way to present the same information and has the advantage of being presented exactly as it was entered in the field, with minor editing in the office.

The drawing can also be further simplified to contain only graphical symbols, allowing for another means of organizing, presenting, and interpreting data. We feel this greatly improves the ability to detect patterns of deterioration.

AutoCAD drawing before TPAS AutoCAD drawing after TPAS
Before: data as previously represented After: graphical representation of same data

In summary, this is a fascinating time to be engaged in the development of systems for direct digital input of facade survey information. The emergence and dissemination of new approaches and the greater power and flexibility of mobile computing is rapidly changing the fields of Architecture, Engineering, and Construction.

Hardware and software development is leaping forward as computers become less expensive, more capable, and more robust. In addition, we are seeing the convergence of CAD and GIS capabilities, which will revolutionize the way we analyze and interpret survey data and influence how we prepare construction documents.

Furthermore, as these technologies grow, so will the number and type of its users. Although there are still unanswered questions and areas for improvement, the development of handheld computers has made an impact on the work of building professionals by creating more effective means of directly recording, interpreting, and managing facade survey data. -excerpted from a presentation by Kent Diebolt

Three helpful references, by Edward R. Tufte (Graphics Press, USA) are:
Envisioning Information (1990)
The Visual Display of Quantitative Information (1983)
Visual Explanations (1997)

To view the complete presentation or download sample files, go to the resources page on our website,

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St. Thomas Church

rusting steel support at st. thomas church
Rusting steel support

During Vertical Access' July inspection of St. Thomas Church, a continuously open horizontal joint extending around the entire northeast turret was noted.  The joint had apparently reopened after being repointed eight years ago.  The four stone pieces capping the turret had lifted off the top of the mortar joint by about 1/8".  After inspection from the inside of the stair, rusting steel support structure was found to be the probable culprit of the open joint.  A follow-up visit on a rainy day confirmed the suspicion - rain was pouring in the open joint, further contributing to the rusting of the steel and the staining of the stone.   

Partially in response to Vertical Access' findings, the Church is in the process of removing and replacing the stone cap and underlying structure. 

To view the Vertical Access St. Thomas project profile, go to -Kelly Streeter


stone removals Angel Estrada
Removed portion of stone cap Angel Estrada


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VA in the News: Structure Magazine

Cleveland tower, Pronceton, NJ
Cleveland Tower, Princeton, NJ

Structural engineers and architects are frequently asked to render opinions on the conditions of building facades and other structure, but may not be allowed a budget that permits hands-on inspection using traditional means of access such as pipe staging, suspended scaffolding or aerial lifts.  Relying purely on visual condition assessments made from a distance often results in a high degree of uncertainty during the design and construction phases of a restoration projects, leading to construction changes order and cost over-runs.

-an excerpt from an article by Kent Diebolt and James Banta

To read the entire article, click here.