Replacing bridges

My commute to work starts with a few mile wander through quiet neighborhoods and then moves onto I-495, 3-lanes northbound, 3-lanes southbound, usually moving at a pretty good clip. There's a two to three mile section of I-495 that has been under construction since the start of my commute to Littleton in early October of 2009. The under-construction section moves one lane of the northbound highway to the southbound side. The remaining 2 lanes were scrunched to the left of the northbound side. That changed a couple of weeks ago so those 2 lanes are now to the right.

Until now, I hadn't a clue about the ongoing work. In fact, the apparent lack of workers on the road for weeks on end really made me wonder.

The mystery revealed itself this week. Heading north on the far left, on the southbound side of the road, now provides a view of the ongoing work that before was quite hidden behind jersey barriers. Amazing! They are replacing three bridges by totally removing the old. When I first noticed the work, the road surface had been removed. Now the steel beams are missing too, and beneath the reopened right lanes it is clear that the under-structure of the (right side of the) bridge is totally new.

I find it fascinating that this type of work can be completed without (totally) closing the highway. Yes, the travel lanes have been moved and scrunched into less space than normal - but the road is definitely open and moving.