Figure Ground Mapping


This is Figure Ground Map of the original extents of Orwigsburg as they are today. The gray figures are outlines of existing buildings give a clear indication of the most densely populated portions of the town. The most recognizable portion of the map is Center Square (at the center of town). This is arguably the most delightful and loved portion of the town today. It is the most fully culminated portion of the plan.

Cardo & Decumanus

The idea of a grid as a system for planning can be traced back to the Ancient Romans. When the Romans set out to build a new castrum in a land that they had conquered, they would typically start out with a strategic center point from which they would establish two main roads, a Cardo (North- South) and a Decumanus (East West). These two streets served as the main two streets that would then expand into a grid that will eventually become many of the European cities that we know and love.

This concept became deeply engrained in European city and town planning and eventually colonial America. Therefore it is no surprise that the two main streets in Orwigsburg are a true Cardo (Warren Street) and Decumanus (Market Street). It is also highly appropriate that the first Schuylkill County Courthouse be built on a lot at the intersection of these streets facing a beautiful town square.

The Rod and Block Sizes

The main way that I was able to correct the GIS map was through the utilization of historical standards for town planning. The basic unit for laying out block, lot and street sizes for centuries, was the Rod. It became standardized in 1625 by Sir Edmund Gunter. This unit can be broken down as follows:

1 Rod = 16.5 Feet

1 Chain = 4 Rods = 66 Feet

1 Furlong = 10 Chains = 40 Rods = 660 Feet

1 Acre = 1 Chain x 10 Furlong

1 Mile = 8 Furlong = 80 Chains = 320 Rods = 5280Feet

These units were the basis for many early towns and villages in the United States and Great Britain. Orwigsburg is no exception to this rule and so it is no coincidence that the original lots, blocks, streets, and limits of the town are exact multiples of the Rod.

Remnants of this mode of subdivision can be seen all throughout the town when examined carefully. Because of this pattern, I was able to correct the GIS map on a grid.

Entering the Digital World… and Then Correcting It.

The next step was to acquire a CAD map from the Borough. Fortunately, one existed. However it was drawn using  GIS (Geographic Information Systems) which are legendary for being highly inaccurate and sloppy.  This map was no exception. It would be fine for broad overviews of the community or for rough zoning, however on any level of detail it would not be sufficient. In order to have the end product for which I am looking, I will need to retrace the entire map and correct the line work based on any patterns I can find or information I can get. The goal of this process is to have an accurate digital model that I can analyze and eventually use for future proposals.