A new Chelsea Street Bridge is being built on top of the old one(which will be demolished at some point during the construction). It is an important link crossing the Chelsea River from East Boston to Chelsea. Besides the McArdle Bridge on Meridian Street, the Chelsea Street Bridge is the only other toll-free option to drive from East Boston and Logan Airport without heading North. The construction company posted a beautiful time-lapse video on YouTube showing some stages of the bridge being built. Just search YouTube for«Chelsea Street Bridge» and you’ll find it. A great video and fun to watch. As for the new bridge itself. so far it looks pretty impressive. Because large cargo ships travel up the Chelsea River, the bridge must open for that traffic. While the old bridge is a Jackknife or Drawbridge, the new one will be a Lift Bridge and it will be much wider. Two very high towers are already in place which will ultimately raise the new center Lift Section to allow big boats to pass. Hopefully the new bridge’s mechanism will be speedy and reliable. It should be a welcome improvement for vehicular traffic through the industrial neighborhoods it serves.