Gap Between Two terrain ...

I am developing the racing game in which i have problem in connecting two terrain.

I have 3 terrain and all of them are repeating one after another when one reach the certain position , it will be placed at the after the last track. everything is going fine but problem is that it leaves gap between two terrain.

how to solve that? plz help me ...

here is my code

TrackA.cs

using UnityEngine; using System.Collections;

public class ATrack : MonoBehaviour {

 public Transform ObjectA;
 public GameObject TrackC;
 
 void Start () {}
 
 void FixedUpdate () 
 {
     
     if(Mathf.CeilToInt(ObjectA.transform.position.z) <= 0)
     {
         //gameObject.renderer.bounds
         //Debug.Log(Vector3.up);
         Vector3 temp = transform.position;
         //temp.z = TrackC.transform.position.z + _TargetExtents.z/2;
         temp.z = TrackC.transform.position.z + 200.0f;    
         temp.x = 10.0f;
         temp.y = 0.0f;
         
         transform.position = temp;
         //Debug.Log(temp);
     }
 }

}

TrackB.cs

using UnityEngine; using System.Collections;

public class BTrack : MonoBehaviour {

 public Transform ObjectB;
 public GameObject TrackA;
 
 void Start () {    }
 

 void FixedUpdate () 
 {
     
     if(Mathf.CeilToInt(ObjectB.transform.position.z) <= 0)        
     {
     
         Vector3 temp = transform.position;
         temp.z = TrackA.transform.position.z + 200.0f;
         temp.x = 10.0f;
         temp.y = 0.0f;
         transform.position = temp;
     
     }
 }
 

}

TrackC.cs

using UnityEngine; using System.Collections;

public class CTrack : MonoBehaviour {

 public Transform ObjectC;
 public GameObject TrackB;
 
 void Start () 
 {
 }
 
 
 void FixedUpdate () {
     
     if(Mathf.CeilToInt(ObjectC.transform.position.z) <= 0)        
     {
     
         Vector3 temp = transform.position;
         temp.z = TrackB.transform.position.z + 200.0f;
         temp.x = 10.0f;
         temp.y = 0.0f;
         transform.position = temp;
     
     }
 }

}