Inverset Units from the Central Artery

Today I went up to Littleton MA to check dimensions on inverset units for a bridge that we are designing in Conway MA. The inverset units were used during the "Big Dig" while the Central Artery was being demolished. The units were designed to be re-used after the project in small bridges across Massachusetts.

The units we were looking at consists of three sections that will be assembled to complete the bridge much like double T's showing up at the site.

The project site in Conway is somewhat of a rural area, so it will be great to see these units reduce the construction time and labor at the site.

Bald Eagle out in Conway MA

Existing bridge in Conway to be replaced

This also reminded me of something I saw the other day showing abandoned projects that were to meant to be part of the green way were the Central Artery once was. I completely agree with most of the projects being abandoned but I wish the YMCA had been given a chance since it would have improved the North Station area greatly.

Lard in Littleton MA where some of the Inverset Units are stored for later use

Back to inverset units tho. These units will allow Massachusetts to quickly improve their infrastructure greatly by replacing small deteriorated structures throughout the state. Hopefully the Accelerated Bridge program at MassDOT will realize the full potential of these units before the units themselves deteriorate.

57 degrees out and still have snow up to our knees

Impact Damage with Broken Welds and Cracked Web

The past two days I was down in Taunton MA at a bridge which spans over Route 140. The rolled steel beam bridge with cover plates was built in 1959 and rehabilitated in 2004 with a new composite deck and railings.

With minor impact gouges on the underside of most of the beams it was only a matter of time before a truck not paying attention to the vertical clearance (14.90' Northbound and 14.74' Southbound) would hit the bridge. Something caused severe damage to Beam #8 (the South most beam in Span #1), deforming the web, bottom flange and cover plate. The impact also cause the web to crack at the diaphragm connections cracking the web to Beams #8 and #7 and braking the weld to Beam #6.

Checking out cracks

POV of a bridge inspector

The state added arrest holes to stop the cracks from propagating and to this date have not expanded past the arrest holes. One vertical rack along the weld on Beam #8 did not have an arrest hole and after doing a Dye Penetrant Test we determined that the crack had not change since the last inspection. 

Broken weld

  

Cracked web with arrest holes

Web pushed outward to the East

Cleaning crack for dye penetrant test prep

After adding dye

Dye Penetrant Test complete showing full extents of the cracking

Section loss at beam ends

Bridge Shielding

Just received a memo from MassDOT for adding a new item to our bridge inspections. MassDOT believes that during inspections the condition, location and material of the shielding should be addressed and I fully agree with them.

MassDOT's district bridge maintenance uses three types for shielding currently (Timber, Expanded Metal and Fabric Wrap) which I have seen at a few bridge located over highways. Even though we have always noted any deficiencies with the shielding in the past, now we will have a guideline for how to address the state before there is a serious problem.