The Muscatine Journal and News-Tribune from Muscatine, Iowa • Page 39

MU5CATINE JOURNAI) AND NEWS-TRIBUNE 30', 1037 i ew Bridges Going Up Under County's Road Program Winter brought to i temporary construction operations on the above two county bridges being constructed by Otto Wendling, Muscatine contractor, under ft contract with the board of supervisors, in Wapsle and Pike townships. Rows of supporting steel point their way skyward In the picture to the left of the Pike township bridge, being built Just County Bridge Problems of Today and Tomorrow west of Nichols. Of concrete rijid frame, the structure will have a clearance span of 46 feet. Steel work, footings and one breast wall were in place at the end of the year. The four wine walls of the new bridge being erected In YTapsie township can be seen in place in the picture to the rignt above.

This structure, electrically-welded with steel rigid frame, will have a clearance span of 34 feet. (By F. P. G. HALBFASS) (Muscatine County Engineer) (Editor's Note: The following article is taken in part from a paper presented before the engineer's section of the State Association of County Officers.

In this paper I will present ou Ideas for development of a coun ty highway bridge system, with special reference to the proced -ure followed in Muscatine coun ty. The predominating thought 2 to 50 years ago, in stream cross construction, was "any way get across just so it could be ac complished safely." Only slov, light traffic needed to be served -and considered. Add Convenience, Beauty. Today, we must add convenl ience and beauty to our considera- The traffic to serve has be- fast, heavy and critical service a bridge renders; and critical of aesthetic promin- In Muscatlns county, on mileage of 630 secondary road miles, we have today 212 bridge, providing stream crossings. One hundred and sixty-two of these are of designs dating back to tha' period of 25 to 50 years ago.

Today, it is very common for these utructures to carry gross loads of 15 tons at relatively high speeds Of the 162 bridges of old design that I mention, a recent in. ipection indicated 27 of these to be in poor condition and in need of overhaul and reconstruction soon. Only 50 of the total num- ber would on 'analysis check ou lor class or heavier loadings '-suitable for speeds over 25 miles per hour, and with floor surfaces that will stand the abrasive action of traffic on gravel. We. have 25 additional bridges where al! but the steel frame-work would safely for a 10-ton con- load.

(Class loading Yepresents a 10-ton concentrated for 16-foot roadway widths and is a minimum used nowdays highway design). Complete collapse of any one of the 162 different bridges can, therefore, oc- any time. The foregoing, then, I will assume is a general summary that the bridge problem of average Iowa county. Bridge YrdoICm Serious. This situation' should empha- vsize to us the great need of tak- 'ing our bridge problem seriously hand, as a whole, and apply- 'ang modern ideas and thoughts to Tour stream crossing structures in to economically and prac- tically meet the oroblem- facing us.

Our plans for service and fi-. must extend into both the and distant future if are to advance with the needs record more of our expendi- for permanency rather than and upkeep. If this is not heeded, traffic automatically put action into and necessitate complete tate control of the problem. It is perfectly proper to con- that every bridge on a con- itructed road needs-to be.brought up to an analyzed 15-ton load capacity and safely crossed by loads at 45 mile speeds. If this is reasonable then, it can well be considered that bridges in need' heavy reconstruction on many the other roads soon will need meet similar demands.

The standard of perfection tha' must begin aiming, at is, i appears, quite clearly dis- Each Unique Study. In a thorough study of a stream' crossing location, we will find; that it is often inadvisable to" use bridge standards bridge site if we are to' "jSjscover the most fitting structure. We find; that the planning of, bridge is a unique study for and-every sitej-to-arrive 1 an tconomic'al type of construction to reasonably give us combined safety, beauty, permanence and greatest convenience for present and 'future use. The only disadvantage Is the increase in costs and study needs for more complicated computations to prepare the correct and exacting surveys and designs. The mere fact of difficult computations should no longer cause county highway departments to resort to standards and avoid the latest engineering and architectural thought on structural types.

In the construction field of great bridges, the old practice of using a few standards for bridge types has already become as antiquated as the old type structures themselves. Material concerns have stepped in and enlarged the standards in order to promote more general use of their products. In our experience, the Iowa Highway commission began drifting away from the use of the old standards back in 1930. They began planning continuous I-beam structures for the primary road systems. In 1933 they extended the use of this type of structure to the secondary road system on request of a county for special design service for some particular site.

They have, also, been broadening the field of standards by analyzing and approving the ideas of material concerns. In the application of modern bridge design and thought to the bridge problems in a county engineer's office, the first requirement is a designing, drafting and inspecting department. Necfl Competent Workers. An expert designer of bridges, like an expert surgeon, must devote all his time and continue his study indefinitely to engineering and architectural design and to new theories of analysis. The draftsman must be competent in mechancal drawing and computation, and the inspector must be qualified to read plans and know and understand the practical application of bridge specifications, in order to achieve the dreams of the designer.

The contractor must be determined by qualification as well as by responsibility. With a perfected organization, as outlined above, 'we should be able to produce concrete in cylinder tests of four to fiv thous- made such a start in organlza tion. It works like this. In thf county we make certain of thorough familiarity with the bridgf problem at hand. We make cos and utility comparisons of design the state standards, standard suggested by material concern and the needs for special design of our own.

Only by comparative study can the wisest conclusion. be arrived at. In the end we pas; all our final plans on to the highway commission for a complete check and approval. This 'consultation with the expert service i renders is as advisable as the consultation of surgeons in surgery. Analysis Essential, We have discovered in our owr work that the standard simple beam, girder, truss, trestle anc "all standards in use today wil continue to have their place They are by no means obsolete and prove out to meet at certain selected sites These all come under the class of staticaDy determinate' structure types.

But the most perfect solution cannot be found withou' cost and service analysis between types, nor without design analysis of the statically indeterminate structure type, as well as study of possibilities for use of the materials of the old existing structure itself. The statically indeterminate stress type includes continuous I-beams and girders, continuous trusses, cantilever trusses, rigid frame bridge of single and multiple span suspensions, and the many types of arch design. An example of the economy resulting from the use of a bridge of the staticaDy indeterminate stress type illustrated by the following comparison of two bridges only a quarter of a mile apart on a road in the river bottoms. In 1930, we constructed over Gedney lake a 108-foot high truss' with two 40-foot I-beam approaches of 1930 standard designs. 20-foot roadway total length 186 feet, at a cost of $22,871.06.

Three years later we planned over Pike creek, in the same river bottom, a 191-foot by 20-foot continuous I-beam bridge, one of the new design developments and the total cost was only $131,681. More than a one-third saving. We are- constructing at the present time a 46-foot by 20-foot concrete rigid frame bridge of our own design west of Nichols. Also under construction is a 34-foot by and pounds per square inch com- 20-foot steel rigid frame with pressive strength at the end of 28 days. The A.

of S. H. O-. permits 1,200 to 1,500 pounds per square inch allowable unit compressive stress in design where this is achieved, and therefore our highway commission, if we can assure hem of this perfection in our work, should be willing to raise allowable stress from their present specfications to 650 )ounds per square inch. In Muscatine county we have concrete wings, abutments, floor and handrail, west of Nichols.

For this latter structure, we are building the four-steel rigid frame by day labor, electric arc welding of the frame parts and utilizing 12,700 pounds of structural steel accumulated from other old bridges. Savings Assured. These two rigid frame bridges are -both of the statically indeterminate stress type and our estimates indicate that savings- will result over other types, par- 1 HAPPY 1 1 NEW YEAR 1 1 Ct.vt ticularly at the site west of Nichols. The use of old steel in this particular structure has not proven as satisfactory as anticipated due to complications that crept in on frabrication work. We have just completed construction of a 67 foot by 20 foot cantilever structure of our own design northweast of Nichols.

The abutments literally hang, and have no piling under them. If a railroad bridge-above is lengthened at some future time and more water diverted down this stream, it is proposed to convert the bridge into a continuous I-beam. This particular design will make the change possible with very little loss of old construction. I should the.standard plans developed by various in-. dustries for promoting the use of their products have a definite bulding up of the members with additional steel arc welds has increased its strength to carry a 15- ton loading.

But here is a use of the old structure is not always the best solution. Only by exam- abandoned. Electric arc welding processes show great possibilities for making it economical to widen and strengthen the best of the old river bridge trusses for reuse in a new structure. Continuous type structures would be analyzed in competition. Engineering study and analysis should be made on such imminant problems now.

In conclusion may I say that I ination and analysis of the exist- I hope I have succeeded in making ing structure and comparison visible to you. a panorama of the with analyses of new or standard public problem and that the great need of organized scientific engineering skill for its development to adequacy and permanency. 61 ViU.il place in the construction Afield, arbitrary reductions in steel types for that particular site do you arrive at the best solution. I mentioned that we had 24 bridges that would analyze safely for a ten ton concentrated load, if only the structural steel members were now. strengthened.

They are all of a 16-foot roadway. These old structures were originally designed for loadings of 100 pounds per: square live with wooden floor systems. The condition of the steel in old bridges, due to rusting and ibr.ajion may require Candy Kitchen at Wilton Is Starting 28th Business Year Wilton Wilton Candy Kitchen is starting its 28th year in business. It is a long and well established eating place in Wilton and "Gus" the proprietor is always on hand to greet the customers. In addition to wholesome lunches, the Candy Kitchen serves ice cream and has a large stock of candy available at all times.

Special booths are main-, tained for women patrons. Paul Jesse's Pool Hall Popular Place for Wilton Patrons Jesse's pool hall has been a popular meeting place in Wilton for the past five years, since its opening. Games of pool and billiards may be played at aoy time or patrons may spend a quiet evening chatting with old friends. but they should not be selected without design analysis and cost comparison. Selection of a structural type just for curiosity or strengths of from 20 per cent to 50 per cent, and, based on a safety factor of four, may check out in their preesnt condition for in Llldl Ui convenience often is very costly.

safe loads as low as two or three Avoiding the increased cost of de- I Tho fon hrirlees to liding sign computations and fact finding only drives away the possibilities of real economy on a long time program. We have also discovered that some old types of steel bridges in our highways can well be considered for strengthening and widening. Electric arc welding is the answer for achieving the re-use of an old structure to meet the demands of today that are made on it. The structure is analyzed and its over-stressed members replaced or strengthened by the addition of new steel. Arc welding design and rigid inspection of all arc welds is necessary.

Strength Increased. Two simple high trusses we recently added to Salisbury bridge, over the Cedar river, in 1936 and tons. The tendency of bridges to deteriorate has thus reached a serious stage in the many bridges originally designed for light loadings, live and dead. Condition of the steel in old structures thus must be considered in the economy analysis for widening and strengthening. Market prices of structural steel, when an emergency arises, must also be We have in Muscatine county six bridges across the Cedar river.

Four of these are on the secondary road system and date back to 1885. For the greatest future welfare of the county three; of these should be abandoned. One new modern structure could be constructed In -a- new.location to replace two of the abandoned ones, and the other should remalr. Greetings From Paul Jesse's Pool Hall Wilton, Iowa CIGARS CIGARETTES BEER BOTTLED OR GLASS by Visiting the Wilton Candy Kitchen Gus Nopoulos Proprietor New Year Greetings From BUY IT OF US' HAWKEYE LUMBER CO. Wilton, Iowa.

Dealers in All Kinds of BUILDING MATERIALS BUY IT OF US Wiring If you do not have the convenience of electricity In your home now, write, phone or slop in at store and we will gladly give you an estimate on installing wiring- and fixtures without cost. Fai Wiring Farmers, you may now enjoy the convenience of electric lights and appliances in your Home, we now fully equipped to install wiring- and fixtures In your home or barns at a very reasonable price. Stop in and ask about it. We Invite You to Inspect Our Display of New and! Modern Fixtures We hope 1938 will, give us the opportunity of serving: you in a friendly and helpful way. May the New Year bring every good wish for you.

11III ELECTRIC STORE General Electric Appliances Refrigerators Ranges Radio Washers Toastmaster MLvmaster Vacuum Cleaner LOUIS G. ELFERS, Prop. 227 East Second Phone 2185.