Extended Inspection Interval

Certain bridges meeting all the criteria for extended intervals of 23 C.F.R. § 650.311 - Inspection interval may be inspected at intervals not to exceed 48 months. TxDOT’s criteria for extended intervals adds an additional requirement which disqualifies bridges containing timber elements in the load path (deck superstructure, or substructure). Bridges that qualify for extended interval inspections will have the same level of inspection for routine inspection as structures scheduled on a 24-month interval. The criteria for application of a 48 month inspection interval is:
  • Deck Condition Rating (Item B.C.01) ≥ 6 [Deck Condition Rating (Item 58) ≥ 6]
  • Superstructure Condition Rating (Item B.C.02) ≥ 6 [Superstructure Condition Rating (Item 59) ≥ 6]
  • Substructure Condition Rating (Item B.C.03) ≥ 6 [Substructure Condition Rating (Item 60) ≥ 6]
  • Culvert Condition Rating (Item B.C.04) ≥ 6 [Culvert Condition Rating (Item 62) ≥ 6]
  • Channel Condition (Item B.C.09) ≥ 6 [Channel and Channel Protection Condition Rating (Item 61) ≥ 6]
  • Channel Protection Condition (Item B.C.10) ≥ 6 [Channel and Channel Protection Condition Rating (Item 61) ≥ 6]
  • Inventory Load Rating Factor (Item B.LR.05) ≥ 1.0 [Inventory Rating (Item 66) ≥ 1.0, when expressed as a rating factor, or Item 66.2 ≥ 36 if expressed as tons]
  • Routine Permit Loads (Item B.LR.08) = A or N. [Structure Open/Posted/Closed Status (Item 41) = A - Open. Note that if a structure is coded with Item 41 = A, it is unrestricted for Routine Permit Loads in Texas.]
  • Fatigue Details (Item B.IR.02) = N
  • Highway Minimum Vertical Clearance (Item B.H.13) ≥ 14.0 [Minimum Vertical Clearance Over Bridge Roadway and Minimum Vertical Underclearance (Items 53 and 54B) ≥ 0420 (i.e., 4.20 m / 14.0 ft)]
  • Span Material (Item B.SP.04) = C01-C05 or S01- S05 [Main and Approach Span Structure Material (Items 43A and 44A) = 2, 3, 4, or 5]
  • Span Type (Item B.SP.06) = A01, B02-B03, F01- F02, G01-G08, P01-P02, or S01-S02 [Main and Approach Span Structure Construction (Items 43B and 44B) = 01, 02, or 05] *See below for notes
  • Scour Vulnerability (Item B.AP.03) = A or B [Scour Critical Bridges (Item 113) = 5 or 8]
  • Scour Condition Rating (Item B.C.11) ≥ 6
The following TxDOT SI&A Coding qualifies for extended inspection intervals. *Member_Type_Main_Span (TXDOT_SI&A_NBI_043.1.3), Member_Type_Major_Span (TXDOT_SI&A_NBI_043.2.3), and Member_Type_Minor_Span TXDOT_SI&A_NBI_043.3.3) must be the following:
  • 01-Weathering Steel (WS) I-Beam
  • 02-WS Plate Girder - Multiple
  • 03-WS Plate Girder, Var. Depth - Multiple
  • 05-WS Box Girder - Multiple
  • 11-Steel I-Beam
  • 12-Plate Girder - Multiple
  • 13-Plate Girder, Var. Depth - Multiple
  • 15-Steel Box Girder - Multiple
  • 21-Concrete Girder - Tee Beam
  • 22-Concrete Girder, Var. Depth - Tee Beam
  • 23-Concrete Box Girder - Multiple
  • 26-Concrete Flat Slab
  • 27-Concrete Slab - Variable Depth
  • 31-PS Concrete Girder - Multiple
  • 33-PS Concrete Box Girder - Multiple
  • 36-PS Concrete Slab - Full Depth
  • 37-PS Concrete Slab - Partial Depth
*Culvert_Span_Type (TXDOT_SI&A_NBI_043.4.1) must be one of the following:
  • 1-Single Box
  • 2-Multiple Box
  • 3-Single Pipe
  • 4-Multiple Pipe
*Culvert_Main_Member_Type (TXDOT_SI&A_NBI_043.4.2 must be one of the following:
  • 1-Steel
  • 3-Concrete
  • 7-Precast/Prestressed
Before for any new, rehabilitated, or structurally modified bridge can be eligible for inspection intervals greater than 24 months, it must receive an initial inspection, be in service for 24 months and receive its next routine inspection.