Lots of train stations that take you to North Station and I would say on average Andover is about 40/45 minutes to the city - of course it depends on which part of Andover.
One way to find out the exact time is to put the address you are considering in Andover and the address for the medical center into google maps and map out the route. It will give you length of time. If you will be traveling in rush hour I would add an extra 15-30 minutes to that time.
Here is every property on the market in Andover:
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Never the same! Depends on time, day, accidents etc. Driving can be fairly quick with little traffic and assuming you're close to 495 or 93 in Andover. Train may take a bit longer, depending on final destination. Commuter rail goes to North Station and then you'll either take the "T" (subway), taxicab or walk to your final place.... more