The measuring tool is not available for a PDF created in MicroStation when using Adobe Reader.
Adobe prevents the measure feature from being used in the free Reader, unless the PDF file's "Enable Usage Rights in Adobe Reader" option has been enabled by Acrobat Professional. Bentley is not authorized to enable that option automatically in the PDF files authored by MicroStation.To "Enable Usage Rights in Adobe Reader", open the file in Adobe Professional, select Advanced - Enable Usage Rights in Adobe Reader. Save the PDF file. Adobe Reader will now allow Measuring.For Adobe Acrobat Pro X this is done by:File - Save As - Reader Extended PDF - Enable Commenting & Measuring