At the time meetings are broadcast live there will be 8 minutes of ads per hour(between 6pm-11pm). So you have to expect a meeting to last a minimum of 20 minutes longer plus 30 seconds intro and outro per ad break.
Speedway is a sport made for TV but I fear not live, its needs to be a hour prepacked programme, covering a couple of meetings and a couple of additional races of incident. Dont expect all 15 heats from a meeting they would drop the poor ones. Now with the limited concentration span of Z's & Alpha's a 60 second race is the ideal length of time to appeal to a new younger generation of fans