This document discusses the historic significance of post-World War II bridges, specifically those made of prestressed concrete. It argues that there is sufficient historic context to evaluate the significance of prestressed concrete bridge types from the 1950s and provides several examples of early prestressed concrete bridges that demonstrate technological innovations and should be considered historically significant at the state level. The document also emphasizes that the historic significance lies in the prestressed concrete beams themselves, not later modifications to the bridges.

1. History Still Matters, or It Should for Effective
Management of Post-WW II Bridges
Why Is It So Vexing To Use History To Evaluate Bridges?
Mary E. McCahon
Historian
TranSystems-
Lichtenstein

2. Some of America’s Most Significant Postwar Bridges
TN-1950
FL-1950
PA-1950 OH-1952

3. From Modest-Looking
Beginning –
Technology Advances
To Stunning Successes
Zakim Bridge Boston (Cable Stayed)
1980s Moreland Interchange (Continous
Box) Metro Atlanta GA DOT.

4. Historic Significance Same As Other Bridge Types: Use NR Guidance
• Shares Common History with Other New Technologies – Think Reinforced
Concrete Types Supplanting Metal Truss Bridges Prior to WW 1.
• Historic Context Varies: Some States Prestressed Leaders, Most States
Followers. Use NR criteria to identify significant examples.
• Under Federalism, States Adopt at Their Discretion. Significance Is At State
Level, Not Federal or National.
• Early Examples of Types & Designs That Become Common Are Significant –
When Technology Is New and Influential.
5 Early of 310 Pre-1960 Are Historic Not All 310 < 1960

5. 1949-1951 Walnut Lane Bridge Introduces P/S to Bridges
1949-1951 @ Fairmount Park,
Philadelphia

6. What Is Prestressed Concrete?
Internally Stressed to Preload Before Live Loads Are Applied
(Think Pre-Compressed)
Pretensioned or Post-Tensioned = Prestressed

7. Why Prestressed Concrete?
• Ancient Structural Principle. Used in TN
in 1907-08.
•Stronger for Given Section.
•Significantly Reduces Deflection Cracking
Under Load.
• Fabricated/Precast Under Controlled
Conditions Continues Well-Established
Pre-WW II Tradition.
• Speed of Building Bridges Using Small
Cranes.
• More Economical Alternative to Steel.
Immediately Proven Advantage.
1907-09 Shelby St. Bridge @ Nashville

8. Near Simultaneous Developments Associated with Walnut Lane Result
in Workhorse Types That Still Dominate
1950
• Conditions Were Right for Innovation & Visionary Leaders.
PA’s Own Box Beam Secondary FL’s I Beam Primary Roads.
Roads. Spring Beam Test Decision to Use for Skyway

9. Box Beam For Secondary Road Use Is PA Product
Concrete Products Corporation of America @ Pottstown, PA
• 7-Stand Wire &
Prestressed @ Factory First
Time EVER
•Achieves H-20 Loading
• Rigid & Lateral Stability
• Up to 50’ Span Lengths
• Easy Transport and
Installation
• PA Dept Hwy Support &
18’-36’ Ready Market
38’-50’

10. Making CPCA Beam
1. Strand in Form
2. Prestressing
3. Sonotubes for Voids

11. Let Us now Praise Famous Men (and Bridges)
“basic element that made the
prestressed concrete industry
possible, practical and
economical in North America.”
C. Zollman, 1981
1955 Use Over Expressway @ PHL
 Workhorse Type
 PA Product
102 Predate 1955
 14 Eligible (pre-1953)

12. FL Hwy Dept Lead on Primary Road Type & Develop AASHTO Beam
William Dean Fl Hwy Dept Selects
P/S Beams for Signature Bridge --
He Leads Nation to Standard
Design Still Used Today
Builds on Walnut Lane Momentum.
Industry Shows Economy &
Technical Qualities; Public Servant
Strives for Better Engineering.

13. Dean Influences National Design Standards That Make I Beam Common
Technology In Many States
Stubby vs Skinny: BPR/FHWA Change & Adopt 1956-57– DOTs Make It Their
Design Standard (Not Innovative; Followers States).
Adopting European Precedent Would Have Been a Calamity for Fledgling Industry.

14. Bill Dean Had It Right
Dean’s Beams Survive. FL State Park.
Walnut Lane Bridge Replaced
1992 Because of Concrete
Cracking & Moisture
Penetration. HAER Recorded.

15. Using Historic Context to Assess Ohio’s 1951-1960 Population
•Leader State with Counties (Not Hwy Dept) Out In Front
1952 Roseville Bridge
Muskingum County
• First P/S I Beam Bridge in State --
(Now Oldest Extant in Nation)
•Listed in NBI as RC, Not P/S- David
Simmons Saved History
• Represents Local Engineers Using FL
Beam Design
• Regional Influence – 400 Attend
Inspection
… it is apparent that in the future prestressed
concrete will be competitive in first cost with
other conventional types of bridges.
R. Mason , Contractor

16. Other OH Engineers & Fabricators Build on Roseville Bridge Success
Despite Success of Box Beam, Still
Experimentation As Pioneers Put
Ideas About Use of Material Into
Different Secondary Road Designs.
1954 2’-Wide Modified T Greene Co.
Charles & William Roberts Work
With OH Counties & Build
Casting Yard to Supply Beams.

17. Ross Bryan Builds First (Opened Before Walnut Lane Bridge) Linear
Stressed Bridge at Jackson (Madison County, TN Late in 1950
1
2
3

18. It’s Technology That Is Significant – It’s All About the Beams, Not
the Deck and Railings
Bridge Had Wider Deck & New
Metal Railings When DOT, SHPO,
FHWA Determine Bridge Historic
Hanly & Young, Cincinnati
Local Engineers Using FL “Stubby” I
Beams For Local Roads
Early Use of P/S I Beams
Hamilton Co. 1953/2001 Early Reuse of P/S I Beams

19. Later Examples Can Be Historic Too
• One of First Instances 100’-
Long Beams
• Represents Milestone in
Evolution of Now Common
Type Dominates Last Half
20th Century
• State-of-the-Art Yard To
Fabricate Needed Length
• Link to Pottstown Origin of
Box Beam.
• History of All Technologies
= Continued Development
1959 Suder Ave @ Toledo

20. Each State Has Its Own Historic Context – This is State Significance, Just
Like Earlier Bridge Types/Designs
Michigan’s Most Significant
1950s Non-Suspension Bridge,
A 1954-55 Box Beam
Industry & Locals Leading-
Promoting

21. Historic Contexts Support Not All States Have Historic P/S Bridges
Georgia Is Follower State:
No Historic P/S Bridges
… Yet
• No Impact on Local Level
Until After Mid-1960s. RC
Precast Designs Rule. (NBI
Error, Actually 25 of Them).
• Adopt BPR/AASHO Standard
Designs Common To Many
States.
• Overpass Bridges Are
Original Design Components of
I System. Look At Plan Sheets,
Funding, Engineers Say So,
and Scholarship Confirms.

22. South Carolina Also Follower State: Evaluations Ongoing
Double Tee Does Double Duty
Strong History Precast Slabs on
Piles by State Forces
Start with P/S Channel Beams in
1955 For Secondary

23. There is Sufficient Historic Context to Assess Prestressed Significance
There Seems to Be Insufficient Understanding of Readily Available History
& How to Conserve Beams
“… there is insufficient historic context/scholarship exists for this period of bridge building
to be confidently assess significance for this structural type.”
“ Character-defining features that contribute to integrity include; the slab [deck?],
longitudinal beams, floor beams [diaphragms?], a parapet or railing if integral, and
abutments, piers and wingwalls, when present.”
“ The fact that ASCE is seeking identification of prestressed concrete structures means that
this bridge type only recently has been perceived as significant.”
A Context For Common Historic Bridge Types, p. 3-102

24. There is Sufficient Historic Context to Assess Prestressed Significance
• Every State Has Its Own Context.
Use Annual Reports & Technical
Periodicals & Conference Proceedings.
• Nationally Applicable Book Still
Available (epub): Incredible Resource.
• Find Old-Timers & Interview Them
Before They Are Gone.
• Understand That Significance Is the
Beams & Technology, Not Cute
Railings.

25. Ah That There Were Ways to Preserve Them
• Problems That Cause Deterioration Same As With Other Bridge Types
• Decks Leak, Drains Clogged, Moisture Penetration Rusts Steel,
Cover Material Spalls, Timber Piles Rot. Sound Familiar?

26. Identify Historic, Then Preservation Through Conservation
“I am on my way to Washington To Look Inside Historic Box Beam Bridges for FHWA.”
Be Proactive About Good Maintenance Practices to Conserve Historic Ones.

27. May The Force Always Be With You To
Understand These Milestones in Civil
Engineering History
Thank You