THE  BROAD  WAY

A Pennsylvania Railroad Home Page
PRR INTERLOCKING  DIAGRAMS

RELEASE NOTES

[ Note to Contributors | Copyright & Licensing Agreement ]

Sources

These are detailed in a separate web page. All are original PRR (or immediately-post-merger PC) interlocking diagrams.

Scanning

Scans were performed on a Hewlett-Packard IIc scanner. John Cooper scanned the maps in his collection. Dick Makse scanned some of his own. The remainder were scanned by Mark Bej.

All maps are scanned into a 2-color format, i.e. black/white. No map as yet has demonstrated a need for shades of gray (save for one map from the Centennial History of the PRR, accessed from a separate web page). Where maps were white lines on dark (generally blue) paper, the colors have been reversed so as to decrease your (over)usage of laser printer toner. The appearance of the original is listed in the References page.

Most maps are scanned at 200 dpi (dots per inch). Most are just over 1000 dots wide (high); length varies considerably. John Cooper scanned most of his maps at 150 dpi, except for ZOO interlocking, which was done in parts at 300 dpi, and as a single sheet at 150 dpi.

Maps in Parts

Those maps which cause problems with Internet browsers have been cut, manually, into two or more parts. These parts overlap slightly for clarity. The entire map is available as well for downloading and printing.

Editing

Editing was performed by John Cooper, EJ Toal, and Mark Bej. Maps were inverted to black on white where needed; stray marks were removed. Where necessary for clarity given the original copy, maps were edited so that track traces, identifying text, signals, etc. were clearly readable.

Why is editing necessary, and why is the original not "good enough"? The original may not initially be thought of as a grey-scale (or blue-scale, I guess) image, but it is. Some things that are easily interpreted when one has the variation of blue available on blueprint sheets to provide you information cannot be understood when the image is "thresholded" to black and white. And keeping full color or even greyscale is prohibitive. Many users (those with slow links) already have long map downloads; compouding it by making the image 4 or 8 times larger would serve no one.

Printing

Most maps on these pages are longer than a standard 8.5"x11" sheet of paper. Your browser likely will do a poor job of printing the map. Either the map will be shrunken to the size of the page, rendering it unreadable; or it will be printed at normal size and cut off.

The best solution by far is to use a sophisticated imaging program, such as the products from Corel or Adobe, or page layout programs from Adobe or Ventura. These programs can rotate the image to print "landscape", printing as much as will fit on a page, and print as many pages as needed to print the entire image. If you don't have these at home and don't wish to spend the (considerable) sums of cash to get them, put the map on a floppy disk and go to your local Kinko's, or equivalent, and use a computer there.

Closer to freeware, Lview prints acceptably those maps that can be read when shrunk to the size of a single page. The Windows 3.1 paint applet will print the image out on as many sheets of paper needed to represent it; too bad it uses so many dots on the page to represent each pixel: the applet seems to be designed for 150 dots per inch printers.

Home
Mark's Railroad-Related Stuff
The Broad Way: A Pennsylvania Railroad Home Page
Maps of the PRR
Interlocking Diagrams
Release Notes

Mark D. Bej
bejm@eeg.ccf.org
+1 216-444-0119
1998-09-23