Activating the command:
 Modify
 Modify Intersect
 Intersect
If in Selection Select
 Select Lines or Selection
 Lines or Selection Select
 Select Construction Objects mode, then choosing the Intersect command will access the Intersect lines dialog. (This can really intersect any object: lines, arcs, circles, and splines.)
 Construction Objects mode, then choosing the Intersect command will access the Intersect lines dialog. (This can really intersect any object: lines, arcs, circles, and splines.) 
Note that two sets of selections will need to be made on the fly. You do not need to make the selections before activating the command. The two selection sets are as follows:
The objects can be lines or construction objects or a mix of both. When using a mix, the Select setting will need to be changed in the middle of the operation.
The procedure to intersect objects is as follows:
 Shape setting, you need to left click the item to select it. To select multiple objects to be intersected, you must pick them one at a time by left clicking on them.
 Shape setting, you need to left click the item to select it. To select multiple objects to be intersected, you must pick them one at a time by left clicking on them. Only objects that are in the same plane can be intersected. However, they do not need to physically cross. If the Use equation of the intersecting entity check box is activated, the equation of the object will be used for the intersection. That is, the object is treated as if infinitely long.
If the Intersect all other lines check box is activated, you will only need to select the objects to create the intersections; not the objects to be intersected. All of the entities that the selected object intersect will be intersected when the <Enter> key is pressed.