i draw string line in Auto CAD bt it cant run in Auto CAD 2013.so plz help me i attached hear that line string but cant run in Auto CAD 2013. plz help me.
Use the 'MX Conversion Toolbar' to convert the AutoCad polyline (or MicroStation SmartLine) to a master string. You will be asked what chainage interval you want. This is a simple (almost) one-click process.
As far as I know, you cannot create proper transitions (spirals) in CAD, so if they are needed, you will have to do further editing of the alignment in MX.
The help file has a full explanation - MXROAD>Help>View>Using Toolbars>Environment Toolbars>MX Conversion toolbar - overview.