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Caveats regarding entries under Type

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Historic Bridge Inventory

The codes given in this list under the principal structural Type refer to the structural type of the earliest surviving superstructure elements of the bridge, whether those elements are currently functioning as principal load-bearing elements or not. This differs from the structural type coding system used in MassHighway's computerized database, which gives the structural type of the superstructure elements that are presently functioning as the principal load-bearing elements of the bridge, regardless of whether those elements are original or were added to the bridge at a later date.

The structure type codes used on the historic bridges list are based on the Federal Highway Administration's coding system. The "type" column indicates the structural type of the main span(s) of the bridge using a three digit code composed of two segments. The first digit indicates the kind of material and/or design by using one of the following codes:

Code Description

1

Concrete

2

Concrete continuous

3

Steel

4

Steel continuous

5

Prestressed concrete

6

Prestressed concrete continuous

7

Timber

8

Masonry

9

Wrought Iron or Cast Iron

10

Other

The second and third digits of the code indicate the predominant type of design and/or type of construction by using one of the following codes:

Code Description

01

Slab

02

Stringer/Multi-beam or Girder

03

Girder and Floorbeam System

04

Tee Beam

05

Box Beam or Girders - Multiple

06

Box Beam or Girders - Single or Spread

07

Rigid Frame

08

Orthotropic

09

Truss - Deck

10

Truss - Thru

11

Arch - Deck

12

Arch - Thru

13

Suspension

14

Stayed Girder

15

Movable - Lift

16

Movable - Bascule

17

Movable - Swing

18

Tunnel

19

Culvert

20

Mixed types (applicable only to approach spans)

21

Segmental Box Girder

22

Channel Beam

00

Other

Examples Code

Timber Through Truss

710

Masonry Culvert

819

Steel Suspension

313

Continuous Concrete Multiple Box Girders

205

Simple Span Concrete Slab

101

Tunnel in Rock

018

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