Explanation:

 A roadblock is a temporary installation set up to control or block traffic along a road. On commercial television, the term is used when an advertiser buys up all the advertising on a channel for a given length of time like a full day (vertical roadblock), or across a band of channels at a particular time, say an hour (horizontal roadblock ), thus preventing any other advertiser from being present at those times.

What the roadblocking advertiser experiences is not dissimilar to what Mrs Sonia Gandhi might be as she cruises down Mumbai???s Western Express highway, past the Sea Link and into Marine Drive. What other advertisers go through is exactly what we do sitting in our cars in the resultant traffic jam, fretting and fuming.