Air Canada Flight (ACA) number 1072, an Embraer RJ-190 on a scheduled 14 CFR Part 121 flight between DEN and Chicago O'Hare International Airport (ORD), Chicago, Illinois, had been cleared for takeoff from the approach end of runway 34R at DEN. At approximately 1334:40, after releasing the parking brake but prior to beginning takeoff roll, the pilot of ACA1072 observed headlights of a vehicle on runway centerline proceeding toward him on runway 34R. The pilot advised the control tower that a vehicle was on the runway after which the tower canceled ACA1072's takeoff clearance and directed ACA1072 to taxi off of runway 34R at taxiway F2 at approximately 1336:10. The vehicle on runway 34R was OPS6, a DEN Aviation Operations Vehicle operated by the DEN Aviation Operations Manager as the lead vehicle for the snow removal vehicle team. OPS6 had requested and had been authorized by the control tower personnel to proceed southbound on taxiway F in preparation for snow removal operations on runway 34R. Taxiway F parallels runway 34R. The operator of OPS6 misidentifed runway 34R for taxiway F and proceeded onto runway 34R at taxiway WC and traveled south on the runway. Once the tower personnel became aware of a vehicle on the runway, they contacted OPS6 as the lead vehicle of the snow removal team to advise him that a vehicle was on the runway. OPS6 did not initially realize that he was the vehicle on the runway. While coordinating with the tower, OPS6 attempted to visually identify the vehicle on runway 34R before realizing that his vehicle was the vehicle in question. The DEN air traffic control tower (ATCT) was equipped with airport surface detection equipment, model X (ASDE -X). The ASDE-X system was designed to aid in identifying and de-conflicting aircraft and vehicles on the airport to assist in air traffic controller situational awareness, and to prevent runway incursions. According to the DEN ASDE-X playback, OPS6 entered runway 34R at taxiway WC at approximately 1333:40 and proceed down runway 34R while ACA1072 was in takeoff position on the runway. The algorithms of the ASDE-X are set to prevent nuisance alerts for aircraft and/or vehicles traveling less than approximately 40 knots. As OPS6 was not traveling at such speed and ACA1072 was stationary, the ASDE-X did not alarm. Staffing in the DEN ATCT included an instructor controller and a developmental controller on local control (LC) 4 position. The LC4 position was providing ATC services for arrivals and departures on runways 34L and 34R at the time of the incident. According to air traffic controller statements, both the qualified controller and the developmental controller stated that the runway appeared to be clear prior to issuing a takeoff clearance to ACA1072. The developmental controller stated that he scanned the runway and the ASDE-X display in the tower and everything appeared clear.