Unity Freezing

When I run this script Unity becomes unresponsive and won't close. I additionally would find it helpful if somebody could share how I could terminate my code if it runs for too long.

The purpose of this script to randomly generate buildings ,insert buildings randomly selected from another array t the corners, and add a gap at the end of the row when the scene loads. I have created and assigned Unity tags: "building" and "cornerbuilding". I have also created the tag "instance"

 using UnityEngine;
 using System.Collections;
 
 public class buildingplace : MonoBehaviour {
     public GameObject[] buildings;
     public GameObject[] cornerBuildings;
     public GameObject streetSpace;
     private GameObject[] Instances;
     //i= current instance
     //r=current selector
     private float addwidth;
     private float distance=0f;
     public float streetLen=20f;
     void Start()
     {
         buildings = GameObject.FindGameObjectsWithTag ("building");
         cornerBuildings = GameObject.FindGameObjectsWithTag ("cornerBuilding");
         //TO DO: loopfor 25 blocks
         for (int i = 0; distance<streetLen; i++)
         {
             int r= Random.Range(0, (buildings.Length));
             float currentW = (buildings [r].GetComponent<Collider> ().bounds.size.z) * .5f;
             //this if will place the first cornder building on the street
             if(Time.realtimeSinceStartup==10f){
                 Debug.Log ("loop closed");
                 return;
                 }
             if(i==0){
                 r = Random.Range(0, (cornerBuildings.Length));
                     Debug.Log(r);
                     Debug.Log(cornerBuildings.Length);
                     Debug.Log (buildings.Length);
                 GameObject frontCornerInst = Instantiate(cornerBuildings[r], new Vector3(0, 0, currentW), Quaternion.identity) as GameObject;
                 frontCornerInst.gameObject.tag = ("instance");
                 distance += currentW;
                 //place last corner building at transform.position.z=streetlen-currentW
                 GameObject backCornerInst = Instantiate(cornerBuildings[r], new Vector3(0, 0, streetLen-currentW), Quaternion.identity) as GameObject;
                 backCornerInst.gameObject.tag = ("instance");
 
                 GameObject streetSpaceInst = Instantiate(streetSpace, new Vector3(0, 0, streetLen+currentW), Quaternion.identity) as GameObject;
                 streetSpaceInst.gameObject.tag = ("instance");
             }
             else{
                 while(buildings [r].GetComponent<Collider> ().bounds.Intersects(buildings [r].GetComponent<Collider> ().bounds));
                 addwidth = (Instances[i-1].GetComponent<Collider>().bounds.size.z)*.5f;
                 distance+=addwidth+currentW;
                 GameObject instance = Instantiate(buildings[r], new Vector3(0, 0, distance), Quaternion.identity) as GameObject;
                 instance.gameObject.tag = ("instance");
                 Debug.Log (addwidth +"_"+ currentW +"_"+ distance);
             }
             Instances = GameObject.FindGameObjectsWithTag ("instance");
         }
         foreach(GameObject building in buildings){
             building.SetActive(false);
         }
         foreach (GameObject cornerBuilding in cornerBuildings) {
             cornerBuilding.SetActive (false);
         }
     }
 }