 
                                    
                            One car length
							                                
                                        
                                    
							                        
                    
                            Two metres (6 feet 6 inches)
							                                
                                        
                                    
							                        
                    
                            A two-second time gap
							                                
                                        
                                    
							                        
                    
                            Two car lengths
							                                
                                        
                                    
							                        
                     
	 
	