Collision Avoidance – Minimum Separation Distance

Overview:  Computes minimum separation distance between vehicles necessary for the Following Vehicle to react and stop with the required distance between vehicles when both have come to a full stop.

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 Collision Avoidance block and click on Separation Distance 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 a .MSD 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:

Entries for the Vehicles in Deceleration will contain two or more of the following data entry blocks within the two leftmost frames:


·        ‘g’ Decel – (Deceleration – required)

·        Speed (Initial)                                                                                       

·        Reaction Time

·        Distance (Safe) – Required distance between vehicles at full stop

Computation Increment & Counters

Output – Unit  (1 / 2):

The output from this module consists of a restatement of the inputs and the Minimum Separation Distance to achieve the input parameters.


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 .  

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

·        Save .MDS 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.MDS” of the data at the close of this module or the close of 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.

·      Xfer – TDMV (Analysis) – Transfers all data to the Time Distance Multiple Vehicle module and calls up this module allowing further analysis of the data and providing an Animation of the vehicles based on the computed Minimum Separation Distance.  Exiting from the TDMV module returns focus to the original CA–MSD module.

·        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.