Railroad Grade Crossings – AASHTO Sight Triangle


Overview:  Computes the required Sight Triangle values at on-grade railroad crossings.


Entry into Module:


This module of the program is normally entered by clicking on the REC-TEC block in the upper left of the REC-TEC Window causing the drop-down menu to appear.  Place the cursor on the Railroad Grade Crossings block and click on AASHTO Sight Triangle on the sub-menu to initiate this module.


Under certain circumstances, the user may choose to use the Files block instead of the drop-down menu approach.  Selecting any file with an .AST extension in the Dialog box accessed from either the Open Single File or Open Multiple Files block opens this module.


Selecting AutoLoad [ON] from either the Setup Menu or the AutoLoad Icon on the upper right side (third line) of the REC-TEC Window automatically loads the scenario that was on the screen when the module was closed, either individually, or when the program was closed.  With AutoLoad [OFF] on the main REC-TEC Window, modules will start without loading a file.


Data Entry:


This module contains the following data entry blocks within the leftmost frame:


·             Speed (Train) – Rail Speed

·             Speed (Vehicle) – Posted Speed Limit

·             Acceleration – Acceleration or Deceleration (required)

·             Distance (| rails |) – Distance between Outer Rails

·             Time (PRT) – Perception Reaction Time (See Formulae)

·             Length (Veh) – Overall Length of Vehicle

·             Distance (Dvr->F) – Distance from Driver to Front of Vehicle

·             Distance (S/Line) – Distance from Stop Line to First Rail


Entry of the variables in the data boxes is sufficient to generate a solution and causes output information to appear in the Output frame.  As the input data is changed, the output data is automatically updated without the need to tell the program to update the output.




The output from this module consists of the repeated input variables plus the Distance down the Tracks and Distance down the Highway.







Several Command Buttons appear in a frame located at the lower right corner of the module Window.  The Command Buttons allow the user to engage options including the option to Open and Save the data required to generate the scenario shown on the screen at the time the file was saved. 


·             Open .AST File – Calls up a Dialog box, which Opens any pre-existing .AST file and displays the output results.


·             Save .AST File – Calls up a Dialog box, which Saves data on the screen to files with any user-selectable filenames.  This is independent of the automatic saving as “LastFile.AST” of the data at the close of this module or the close of the program.


·             Formulae – Opens a word processor (set by the user in Setup) with a file showing the basic formulae used in this module of the program.  While the user may add to or modify the information in this file, it does not change the formulae imbedded into the program.


·             Formulae* - Toggles a frame displaying the formulae for computing the unknowns in this module.  In addition to the basic formulae, the frame shows intermediate steps with the actual input data shown in the computation. 


·             Graphics – Displays the graphics from the AASHTO Manual.  [Esc] to Exit


·             Documents (rec-tec.com) –Documents by Joseph A. Hinton, which are invaluable in assisting with preparation for Railroad Grade Crossing cases.


·             N – This button toggles a graphical number pad on the screen that can be used to enter data into the input boxes without using your keyboard number pad.  This may be useful for presentations as data entry can be accomplished using a wired/wireless mouse.