I have a collection like this: 

```
{'speed':45, 'time':1446271000},   
{'speed':45, 'time':1446271001},   
{'speed':63, 'time':1446271002},    
{'speed':68, 'time':1446271003},  
{'speed':70, 'time':1446271004},    
{'speed':59, 'time':1446271005},   
{'speed':55, 'time':1446271006},    
{'speed':61, 'time':1446271007},    
{'speed':62, 'time':1446271008},   
{'speed':63, 'time':1446271009},    
{'speed':67, 'time':1446271010}   

```

I want to summarise the high speed (speed >=60) records, so the result should look like: 

```
{'speed':63,'duration':2,'start': 1446271002,'end': 1446271004}  
{'speed':61,'duration':3,'start': 1446271007,'end': 1446271010}

```

How should I achieve this?