Security at the arena where the Democratic Party is holding its presidential nominating convention has been increasing steadily since the convention began Monday. The security cordon was at its tightest Wednesday, the day former President Clinton spoke. It was already very difficult to gain access to the Pepsi Center, but late Wednesday was especially difficult.

Part of the reason may have been some demonstrations taking place near the arena. A street leading to an entrance checkpoint south of the Pepsi Center was packed with riot police, ready to prevent any protesters from entering the street. Near the entrance, riot police formed a cordon, diverting people with convention credentials into a narrow passage way between them and a barricade. Police also stop the press from taking pictures of them or the security measures.

The concerns about car and truck bombs forces security agencies to cordon off vehicular access around sites that are holding high profile events. like the Democratic Convention. At the Pepsi Center, no unauthorized vehicles are allowed within around two kilometers of the main building. Some authorized shuttles buses are allowed a little closer to the area, but the security measures requires a walk of about one-and-a-half kilometers.

VIPs, such as former President Clinton, are of course driven to up a VIP entrance with a police escort. When Mr. Clinton arrived at the Pepsi Center Wednesday night, police aggressively shouted at people to get out of the road.

The measures are partcularly cumbersome for the thousands of journalists who have to carry large pieces of equipment around. All belongings are checked in huge tents that have rows of metal detectors set up to screen the thousands of people and journalists who enter the area each day.

Security is expected to be even tighter on the last day of the convention, which will be held at the city's professional football stadium, Invesco Field. Up to 75,000 people are expected to hear Senator Barack Obama accept the Democratic Party's presidential nomination.