9AM UPDATE:&nbsp;Alternating traffic conditions are now in place at the site of a diesel spill near Katoomba.&nbsp; Live Traffic NSW warns motorists to allow for more travel time.&nbsp; EARLIER:&nbsp;The Great Western Highway was closed in both directions due to a diesel spill. The spill was caused by a truck and car accident that occurred near Explorers Road, just outside Katoomba. The accident occurred at about 5.15am on January 18. Transport Management Centre spokeswoman Melissa Hunter said no diversions were in place on the highway. As a result, Ms Hunter said traffic in both directions were&nbsp;being held on the site. “Motorists can consider using Bell Line of Road instead,” she said. Emergency services and traffic crew personnel remain on site. Motorists are advised to avoid the area if possible as there are heavy traffic conditions. Allow extra travel time if you must travel on the highway on Thursday morning. Ms Hunter said the highway was expected to “remain closed for some time”.