Layout Design - 8 - Technical Specifications

Prototype Information

A railroad's operations is only as good as its personnel, operating plan, and its physical plant (right of way, yards, locomotive and rolling stock).

In order to ensure that each and every spect of operations is efficient, a series of documents outlining that departments operations is maintained. It is the same with the maintenance of way department.

The maintenance of way department is no exception. The department maintains a series of technical specifications on a wide variety of bridges, buildings, tools and track components used withing the railroad company system.

Fortunately there are two excellent sources of this information on the internet. 

• Robert Schoenberg maintains a series of Pennsylvania Railroad system Standard MOW plans. 
• Don Strack maintains a series of web pages that contains portions of the Union Pacific Common Standards book, a collection includes a large variety standards dating from 1904 to 1985.

Railroads standards were also on occasion mandated by law. I found (somewhere) a consolidated spreadsheet by state and track clearance requirements.

Check out your prototype railroad historical society or web site to see if there are standard plans applicable to your operations.

Modeling Information

The National Model Railroad Association (NMRA) has a series of Recommended Practices (RP) developed for satisfactory model operations based on existing model railroad equipment v. radii of curves and size of turnouts. Those figures, relationships or dimensions were established through actual tests and feel to be beneficial to model operation. Those recommended practices have been updated over the years, and the format I found the most interesting was RP-11, Curvature and Rolling Stock, Revised 1-90.

Andy Hamilton in the February 1991 National Model Railroad Bulletin suggested that 'Class' could be used in the hobby as a means of identifying the look and feel of the layout as it relates to operations, right of way construction and maintenance, locomotive, and rolling stock selection. 

 

Andy proposed that Prototype Class 1 operations would be expected to have broad radius curves and high speed (high number) turnouts, compared to prototype Class III operations (such as switching lines) that could be expected to have sharp radius curves and slow speed (low number turnouts).

 

The WWSL, the OPLC and the STC are Class III railroads. Using the RP format, recommendations for would identified under two Keys: 

Key F - MU and Light Electric

Key M - Standard Trunk Line

 

 

The WWSL

One day the WWSL will maintain a Common Standards book. In the meantime, you'll find those specific standards listed in the WWSL Right of Way Specifications and Modeling section of this web site. 

For general planning and construction purposes:

Human Factors. Here are the human factors used to develop the WWSL layout plan. 

Specification	In inches
Aisle widths – normal	48
Aisle widths – constrained	30
Benchwork height – upper level	56
Benchwork height – lower level	34
Minimum track setback from Aisle	4
Minimum track setback from wall or backdrop	8
Maximum reach in distance from aisle to track	27
Bench work width for shelf style	24
Module standard width	24
Module standard length	96

Track Planning Standards.  The next step was to develop a set of standards for the trackwork. It would permit operations by virtually all HO scale equipment I would use in WWSL operations.

Specification                                     (In inches)	WWSL	OPLC	STC
Typical equipment length	40	40	40
Maximum equipment length	70 [1]	50	50
Track centers, double track, tangent	2	2	2
Track centers, tangent, Type 2 cantenary pole	3
Track centers, arrival departure track	3
Track centers, yard	2	2	2
Track centers, siding industrial track	3
Track centers, double track, minimum curve
Turnout number, single	5	6	5
Turnout number, crossover	6	8	6
Turnout number, ladder	5	6	5
Track curve, minimum radius, main line	26	26	26
Track center, double track, minimum radius		2	2
Maximum grade %	2.5
Vertical curve multiplier
Easement	28
Super-elevation	None	None	None
Minimum over/under track separation	3	None	None

Reference

NMRA recommended practices are:  

• RP-7 Track Centers and Obstacle Clearances
• RP-10 Trackwork - General
• RP-11 Curvature and Rolling Stock
• RP-12 Turnouts - General

 

 

 

NMRA recommended practices are: RP-7 Track Centers and Obstacle Clearances RP-10 Trackwork - General RP-11 Curvature and Rolling Stock RP-12 Turnouts - General