how to serialize the multi dynamic data in object

Question

I want the response like below JSON formate, how to do.

 

{"Spans":[

{

"Cant":0.0,

"ContactHeight":5935.0,

"CatenaryHeight":5935.0,

"Stagger":-717.0,

"Kilometerage":26.714,

"TrackName":"1100",

"RouteId":"LEC1",

"StructureName":"G-17-5"

},

{

"Length":62000.0,

"Versine":0.0,

"Features":null,

"SpanType":"AnchorSpan"

},

]

}

 

this is class that I have created

public class SpansItem
{
public int Cant { get; set; }
public int ContactHeight { get; set; }
public int CatenaryHeight { get; set; }
/
public int Stagger { get; set; }
public double Kilometerage { get; set; }
public string TrackName { get; set; }
public string RouteId { get; set; }
public string StructureName { get; set; }
}
public class Root
{
public List <SpansItem > Spans { get; set; }
}