tiffany wolfson explains it's because of new involvement by homeland security. >> reporter: earlier thisust pull up and start unloading. today the protocol is totally different. they must come to peer 96 fir and here they're met by u.s. customs and border protection, a department of homeland security. a truck scans both sides for any signs of radiation. then iive imaging truck runs alongside almost like a car wash. >> what we have here is our large scale equipment. we're looking for both radiation and also using our imaging equipment to make sure there's nothing inside the vendor's trucks. >> reporter: from here, the drivers are given a unique placard. the drivers are escorted to the second entrance of at&t park, where homeland security officials and sfpd are stationed. >> we just escort to make sure that the trucks are in the same condition that they were in when they were here at this facility. >> steven baxter says it's necessary given how many fans will fill the stadium. >> it's obviously a big national event and drives home lots of people and attention and just has that higher profi