I couldn't answer that. I'm not a pipeline engineer. I'm sure they could last 100 years if they're well maintained.
I think Mike mentioned we've got 30 or so pipelines crossing the river here, and there have been no difficulties since they've been put in. Pipelines are a safe way of transporting energy. They're safer by far than trucking, barging or boating and rail. It doesn't take much to derail a train. Again, the pipeline has a lot of backup systems so if there is a spill it can be shut immediately, reducing the amount of spillage into the environment.
How long do they last? I can't tell you. Accidents do happen occasionally, but I know Enbridge and other pipeline companies have exceptional maintenance programs because of the heightened awareness of what will happen if there is a spill.
I'm not worried. I trust the people, and they have an excellent safety record as far as I'm concerned.