Caught in an 11-mile traffic jam during the hottest July day on record sweltering motorists could only assume there had been an accident. It was only, several hours later, as they finally approached the trouble spot, that they discovered there was no crash. Instead, council officers had chosen the day that temperatures touched a record-breaking 97.7f (36.5c) to hold a traffic census. And even when asked by police to call it off, they refused. Yesterday furious drivers slammed Essex County Council, who carried out the roadside interviews on a busy main road during morning and evening rush hour.