What, When & Where to Weigh
Weight is the basis for railroad shipping charges — all loads not covered by special contracts or tariffs must be weighed. Newly loaded cars are weighed as close as possible to their loading point, either by the shipper or by the originating railroad. Some receiving customers, especially facilities such as port terminals, also weigh incoming deliveries.
Consider how your railroad's transportation plan (its pattern of customers, shipments, local and through freights) determines track scale locations and train crew work orders:
- Which customers originate loads in your modeled territory?
With the exception of the last question below, these are the only loads you need to consider for weighing.
- Which customers are likely to have special shipping contracts?
Eliminate weighing considerations for special shipment customers, such as TOFC service.
- Are any customers large enough to do their own weighing?
These customers (or collection of customers such as one company's coal mines) are candidates for private industry track scales. Trains that service these customers will need weighing instructions in their work orders.
- What trains (or yard delivery jobs) collect newly loaded cars, and where do they terminate?
These locations (if modeled) are candidates for track scales to weigh the originating freight. And their yard crews will need work orders with weighing instructions.
- Do any trains, such as locals, pickup and deliver the same load before returning to a yard?
These loads will need to be diverted to a nearby yard for weighing before delivery.
- Are there large receiving industries or trans-shipment facilities, such as a port terminal, on your railroad?
Sugar mills, steel mills and other industries that receive large quantities of raw materials are candidates for track scales. Trains or yard crews that service these customers will need weighing instructions in their work orders.
From your above answers you should now be able to list:
- Shippers that will weigh loads.
- Receivers that will weigh loads.
- Yards that will weigh loads.
- Yard and train crews that will weigh loads.
How to Weigh: Static vs. Weigh-in-Motion
Prototype track scales are designed for either static or weigh-in-motion (WIM) weighing:
- Static: The rail car must be completely uncoupled and stopped on the track scale to be weighed.
- WIM: A cut of cars is pulled across the track scale at about 4 miles per hour, and each car is weighed as it crosses the scale.
Decide which method is more appropriate for your railroad and document your road's procedures for your operating crews. The May 2009 issue of Model Railroader article describes weighing cars on a model railroad in detail.
The WeighStation™ Track Scale supports both static and WIM weighing.
Train Movement & Track Scales
Track scales, even today's modern WIM scales, are susceptible to damage from normal train movement:
- Traditional beam scales are installed with a gantlet track arrangement that allows engines to bypass the live scale rails. Engines must never travel over the scale rails.
- Modern load cell scales are typically installed on a single track allowing both engines and cars to travel over the live scale rails. Engines must never stop on the scale, and speeds are limited to 5 MPH.