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September–November 2001
Center for Transportation Research and Education
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2 Understanding how snow moves4 Concrete Chemistry, Microstructure,
and Performance Workshop4 Correction—and more—about
flowable mortar5 ERIS: Improving agency communica-
tions with emergency response providers6 When are three lanes better than four?7 Preventing dangerous edge drop-offs
8 Highlights from Iowa’s supplementto the MUTCD
9 Better mousetraps abound!9 A winning mousetrap: telescoping
bridge rail10 New library resources11 Conference calendar11 FHWA Concrete Admixture Workshop12 2001 “roadeo” results
Acronyms in this issueAASHTO American Association of State Highway and Transportation Officials
CTRE Center for Transportation Research and Education ISU Iowa State University
FHWA Federal Highway Administration LTAP Local Technical Assistance Program
Iowa DOT Iowa Department of Transportation MUTCD Manual on Uniform Traffic Control Devices
PREVENTING SNOW from drifting on roadways is lessexpensive and time consuming—and safer formotorists and maintenance crews—than removing itfrom the road.
For example, plowing snow can cost up to 100 timesmore than installing snow fences.
Three general guidelines for reducing snow drifton roads include shaping the roadside topography,minimizing the use of roadside guardrail, andplacing snow fences.
Shaping topographyPerhaps the best way to control drifting snow is toshape the roadside landscape appropriately. Ideally,this is accomplished when the roadway is designed,but sometimes the topography of existing roadwayscan be improved or reshaped in the following ways.(Implementing either technique likely requires aright-of-way agreement.)
Enhance ditches. Snow tends to accumulate in shel-tered depressions rather than on the higher groundaround the depressions. Widen and deepen ditchesto increase their capacity to contain blowing snowand snow plowed off the roadway surface.
Eliminate snow traps. Snow traps occur when road-sides are higher than the road’s surface. Blowingsnow collects and swirls in these depressions, creat-ing hazardous road conditions. Eliminating snowtraps involves removing embankments to flatten theadjacent roadside and constructing adequateditches.
(For how-to suggestions regarding removing snowtraps, see a related article in the November/
Managing drifting snow
December 2000 issue of Technology News,www.ctre. iastate.edu/pubs/Tech_News/2000/.)
Minimizing the use of roadside guardrailRoadside guardrail can trap snow on the roadway.Ideally, good road design eliminates or minimizesthe need for many guardrail installations. Forexample, building gentler slopes on embankmentsand ditches and extending culverts can reduce theneed for guardrail.
However, when guardrail is necessary, choosedesigns that interfere as little as possible with snowremoval activities. Of the four common designs—box-beam, cable, concrete, and W-beam—box-beam and cable may be preferable because theyallow better airflow and interfere less with snowremoval activities. As illustrated below, blowingsnow can move more freely through box-beamguardrail but tends to collect in drifts near W-beamrail.
SNOW continued on page 2
2 SEP–NOV 2001
Understanding how snow moves
Understanding the characteristics of blowing snow can help you select optimum strategies forreducing snow accumulation on your roadways. Snow generally moves in three ways: by creep,saltation, or suspension (also called turbulent diffusion).
Particles too large to be lifted off the ground in a light wind creep or roll along the ground sur-face. Creeping snow is easily trapped by snow fences.
Lighter snow particles may saltate, or jump along the ground. These particles rise vertically andthen return to the surface at a shallow angle trajectory. Saltating particles can be particularlyproblematic because they can dislodge particles that have become frozen to surface material, in-creasing the amount of blowing snow. The good news: saltating snow is also easily trapped insnow fences.
Suspended snow has become airborne and remains so for extended periods of time. Particlesbecome suspended when the wind is strong and/or snow particles are relatively small. Once sus-pended, they become smaller through evaporation and then tend to be carried even higher.
Most blowing snow is in suspension, with the greatest amount of suspended snow within threefeet of the surface. Suspended snow only stops moving in sheltered areas. To be caught in a snowfence, suspended snow must settle in a sheltered area.
Snow particles do not move for long distances. As they move, they break into smaller pieces,perhaps become airborne, and eventually evaporate.
For more informationBoth Design Guidelines for the Control of Blowing and Drifting Snow (P2381), a publication ofthe Strategic Highway Research Program, and Controlling Drifting Snow (P718) by StanleyRing, Iowa State University professor emeritus of civil engineering, contain helpful discussionsof snow movement. Contact Jim Hogan, CTRE’s library coordinator, 515-294-9481,[email protected]. •
Modify existing guardrail so it doesn’t collect drift-ing snow by anchoring the ends in the back slope orflaring ends away from the roadway.
Placing snow fencesWhen reshaping topography is not an alternative,the next best choice is to manage blowing snow insuch a way that drifts form adjacent to the roadwayinstead of on it. Snow fences, living and artificial,decelerate snow-laden winds, causing snow tocollect at the point of deceleration rather than onthe road.
The theory is simple enough, but properly installingsnow fence is a science that considers overall topog-raphy, average wind speeds, fence design, and otherfactors. Inappropriately placed or designed snow
fences can actually exacerbate the formation of snowdrifts on roadways.
Artificial snow fences. Artificial, or structural, snowfences can be temporary or permanent.
Temporary structures, generally four-foot high,portable plastic or wooden fences, are usuallyinstalled after the fall harvest and removed beforespring planting.
Permanent structures of various designs and materi-als generally occupy a narrow strip of land andrequire little maintenance.
Living snow fences. Trap snow “naturally” by (1)planting living snow barriers, (2) leaving croplanduntilled, or (3) leaving a few rows of unharvestedcorn in the field.
SNOW continued from page 1
Technology News is the newsletter ofIowa’s Local Technical Assistance
Program (LTAP). LTAP is a nation-wide effort financed jointly in Iowa
by the FHWA, Iowa DOT, IowaGovernor’s Traffic Safety Bureau,
Iowa Highway Research Board, andIowa State University Extension.
Subscriptions to Technology Newsare free. To subscribe or obtain
permission to reprint articles,contact the editor (below).
The mission of Iowa’s LTAP is tofoster a safe, efficient, environmen-
tally sound transportation systemby improving the skills and
knowledge of local transportationproviders through training, techni-
cal assistance, and technology transfer, thus improving the quality
of life for Iowans.
Iowa’s LTAP is housed and admin-istered at Iowa State University’s
Center for Transportation Researchand Education (CTRE):
CTREIowa State University Research Park
2901 S. Loop Dr., Suite 3100Ames, IA 50010-8632515-294-8103 (voice)
515-294-0467 (fax)www.ctre.iastate.edu/
Stephen J. AndrleDirector of [email protected]
Duane SmithAssociate Director for Outreach/
LTAP [email protected]
Marcia BrinkEditor
Tom McDonaldSafety Circuit Rider
Sharon ProchnowProgram Coordinator
Melanie AuenBridget Moore-Riannon
Michele RegenoldContributing Writers
Any reference to a commercialorganization or product in thisnewsletter is intended only for
informational purposes and not asan endorsement.
The opinions, findings, orrecommendations expressed in thisnewsletter do not necessarily reflect
the views of LTAP sponsors.
Iowa State University and theCenter for Transportation Research
and Education provide equalopportunities and comply with
requirements of the Americans withDisabilities Act in programs and
employment. Call the AffirmativeAction Office, 515-294-7612, to
report discrimination.
PRINTED WITH
SOY INKTM
3 SEP–NOV 2001
LTAP Advisory Board
The people listed below help directthe policies and activities of Iowa’sLocal Technical Assistance Program(LTAP). Contact any of the advi-sory committee members to com-ment, make suggestions, or askquestions about LTAP.
Saleem BaigLocal SystemsIowa Department ofTransportationTelephone: 515-239-1051
Gary FoxTraffic andTransportation DirectorCity of Des MoinesTelephone: 515-283-4973
Kevin GilchristSenior Transportation PlannerDes Moines MetropolitanPlanning OrganizationTelephone: 515-237-1316
John GoodeMonroe County Engineer641-932-7123
Neil GuessHoward R. Green Company515-278-2913
Bret HodnePublic Works SuperintendentCity of West Des MoinesTelephone: 515-222-3536
Larry JesseLocal SystemsIowa Department ofTransportationTelephone: 515-239-1528
Susan KlekarIowa Division, FederalHighway AdministrationTelephone: 515-233-7302
Wally MookDirector of Public WorksCity of BettendorfTelephone: 319-344-4128
Bob SperryWebster County EngineerTelephone: 515-576-3281
Wade WeissGreene County EngineerTelephone: 515-386-5650
(1) Buffer strips of native grasses adjacent to road-ways can resist the weight and slow the speed ofmoving snow, trapping snow from two to threeaverage snowstorms. They can also help prevent siltaccumulation in ditches, reserving the space forsnow.
One aspect of the reauthorized federal ConservationReserve Program (CRP), which provides conserva-tion incentives to landowners, involves plantingsuch buffer strips.
Rows of trees or shrubs can also make effective snowfences. The distance that snow will drift on the leeside of the windbreak depends on the windbreak’spermeability.
Less permeable windbreaks cause snow to accumu-late in deep, narrow drifts; more permeable wind-breaks cause snow to accumulate in shallow, widedrifts.
The Iowa DOT’s general living snow fence designconsists of two rows (five feet apart) of trees andshrubs, with plants spaced three feet apart withineach row. Rows are placed at a distance from theroadway at least 10 to 12 times (preferred, 15 times)the height of the plants.
The Natural Resources Conservation Service(NRSC), one of CRP’s partners, offers a cost-shareprogram with farmers for planting trees and shrubsto serve as windbreaks.
(2) Natural vegetation on untilled acres can helpprevent snow from blowing onto roadways.
The NRCS also pays landowners to leave highlyerodable lands untilled. (Landowners may remem-ber a similar state program called the Wind ErosionControl Incentive Program (WECIP).)
(3) For several years, some Iowa counties and theIowa DOT have contracted with farmers across thestate to leave a few rows of corn unharvested in theirfields, parallel to the roadway, as a snow barrier. Theprogram can benefit both agencies and farmers.
For more informationFor more information about
• designing and placing snow fences, see SHRP’sSnow Fence Guide, P801.
• working with landowners to install temporary orpermanent structural fences, contact DennisBurkheimer, Iowa DOT winter operationsadministrator, 515-239-1355,[email protected].
• working with farmers to leave rows of corn intheir fields through the Iowa Cooperative SnowFence Program, contact Dennis Burkheimer,Iowa DOT winter operations administrator,515-239-1355, [email protected].
• working with the Natural Resources Conserva-tion Service and Conservation Reserve Programto create living snow fences, contact your localNational Resource Conservation Service(NRCS) office. For Iowa office information, seethe NRCS web site, www.nrcs.usda.gov/.
• understanding the snow drift implications ofguardrail, contact Safety Circuit Rider TomMcDonald, 515-294-6384,[email protected].
• controlling drifting snow, see the StrategicHighway Research Program’s (SHRP) DesignGuidelines for the Control of Blowing andDrifting Snow, P2381.
To borrow the referenced publications, contactJim Hogan, CTRE’s library coordinator,515-294-9481, [email protected]. •
Temporary snow fence of corn rows(not to scale)
4 SEP–NOV 2001
Understanding thecomplexities ofconcrete mixes
Concrete Chemistry, Microstructure, andPerformance WorkshopNovember 14, 2001Ames, Iowa
If it’s been a while since you reviewed thecomplexities of modern concrete mixes, thispractical workshop will teach you about
• the basics of current cements
• the importance of various materials andadmixtures
• supplementary cementitious materials
• changes during hydration andmicrostructure development
• effects of concrete chemistry on durability
Concrete materials have changed dramatically overthe years. They now include finer ground cements;blended and special cements; supplementary mate-rials such as slag, fly ash, and silica fume; and a widerange of admixtures. Climatic conditions such asfreeze/thaw cycles take their toll and so do frequentapplications of deicer salts.
Therefore, it is critical that selecting propermaterials be given paramount consideration inconstructing a durable concrete pavement that can
resist weathering action,chemical attack, abra-sion, or any other pro-cess of deterioration.
Workshop registrationinformation is in themail and online atwww.ctre.iastate.edu/calendar/.
For more information,contact Harold Smith,training and publicworks engineer, Centerfor Portland CementConcrete PavementTechnology, Iowa StateUniversity,515-294-4218,[email protected], orsee www.ctre.iastate.edu/calendar/. •
Concrete materialshave changed
dramatically overthe years.
FLOWABLE MORTAR mix specifications were incorrectin the July/August issue of Technology News (page6). Correct specifications for one cubic yard ofstandard flowable mortar are
• cement: 100 pounds
• fly ash: 300 pounds
• fine aggregate: 2,600 pounds
• water: approximately 70 gallons
A variation on standard flowable mortarIn very tight areas that are difficult to excavate and/or compact, controlled low-strength flowablemortar (also known as controlled low strengthmaterial, or CLSM) may be the preferred backfillfor storm or sanitary sewer, water line, and utilityconduit trenches.
Controlled low-strength flowable mortar has thefluidity and other advantages of standard flowablemortar, but it is much easier to excavate. In fact, it’scommonly removed with a back hoe.
In addition, because controlled low-strengthflowable mortar more closely simulates the com-pacted natural earth surrounding the trench, fewercracks tend to develop in the pavement slab alongtrench boundaries. That is, controlled low-strengthflowable mortar can minimize or eliminate the“beam effect.” This is particularly true in shallowtrenches where the mortar encasement (or arch orbedding) is close to the pavement and/or whenthe earth adjacent to the trench has a tendency tocompact.
But, of course, controlled low-strength flowablemortar isn’t as strong. Standard flowable mortar hasapproximately half the weight-bearing strength ofportland cement concrete; controlled low-strengthflowable mortar has less strength than standardflowable mortar but more than the surroundingearth.
Proportions for one cubic yard of controlled low-strength flowable mortar (from the Central IowaStandard Design and Specification Manuals) are
• cement: 50 pounds
• fly ash: 250 pounds
• fine aggregate: 2,910 pounds
• water: approximately 60 gallons •
Correction—and more—about flowable mortar
Editor’s note: See page 11for information on arelated event: FHWAConcrete AdmixtureWorkshop.
5 SEP–NOV 2001
Jacqueline Comito, affiliate instructor of anthropol-
ogy, Iowa State University, and director of ERIS
project development team
IN IOWA, local communities assume most responsi-bilities for maintaining efficient emergency responseservices. Without joint planning and open commu-nication between communities and transportationagencies, state highway projects, road closings, andother incidents outside community control caninterfere with emergency response decision making.
The objective in developing Iowa’s EmergencyResponse Information System (ERIS) is to improvecommunications between Iowa DOT planners andoperations personnel and local emergency responseservices, thereby helping to improve emergencyresponse time and the survival rate of crash victimson highways.
The concept for an emergency response informationsystem began with a case study evaluation of theeffect of the relocation of Highway 218 on localcommunities’ response capabilities in Washington,Henry, and Lee counties. In cooperation with theIowa DOT’s Office of Traffic and Safety, and usingGIS-ALAS, a geographic information systems ver-sion of the Accident Location and Analysis System,response boundaries and fire district names in thethree counties were added to detailed maps of thetownships, cities, and transportation systems in thethree counties.
The Iowa Safety Management System CoordinatingCommittee (SMS) provided seed money to expandthis preliminary mapping work. Maps of emergencyresponse districts were layered with the location ofemergency response stations, vehicles, and equip-ment, and ERIS was created.
By including attributes such as level of emergencyresponse capability, number and availability of per-sonnel, hospital locations, vehicles, equipment,population, etc., a powerful tool is being developedfor both state and local organizations.
Now with information for 10 Iowa counties, ERISprovides a system of easily retrievable information tohelp Iowa DOT planners and operations personnelcommunicate with emergency response servicesbefore and during construction, emergency condi-tions, weather events, temporary road closings, andsimilar events in those counties.
On the local level, ERIS is an effective assessmentand planning tool for local emergency response pro-viders. In addition, ERIS will create an importantcomponent in the education of emergency responsepersonnel and their communities in the importanceof traffic safety and the benefits of strong ties toIowa’s transportation agencies.
By January 2002, ERIS will be up and running withdata from 17 counties chosen as pilot regions.
For most counties, however, fire and emergencyresponse boundaries are still being hand-mapped bylocal officials and are not accessible on a state level.The Iowa DOT is one of the few state agencies withthe technological resources to conduct a statewidemapping of Iowa’s fire/EMS districts. It is impor-tant for future road safety that this mapping projectbe completed on a statewide basis. •
Editor’s note: This article was originally published inthe fall 2001 issue of Safety Lines, the newsletter of theIowa Traffic Control and Safety Association. A moredetailed version is online at www.ctre.iastate.edu/pubs/Tech_News/2001.
ERIS: Improving agency communications withemergency response providers
[A] powerful tool isbeing developed forboth state and localorganizations.
Photo of emergency responders courtesy ofMercy Medical Center, Des Moines, Iowa.
6 SEP–NOV 2001
GUIDELINES are now available to help Iowa trafficengineers determine when a relatively quick, easy,and inexpensive improvement—re-marking a four-lane, undivided roadway into three lanes, with onelane in each direction and a center two-way left-turnlane (TWLTL)—might be an option for a roadway.
Funded by the Iowa DOT’s Office of Traffic andSafety, Keith Knapp, former assistant professor ofcivil and construction engineering at ISU and man-ager of safety and traffic programs at CTRE, andKaren Giese, former graduate research assistant atCTRE, recently studied such conversions.
Sometimes simpler is betterTo improve operations and safety along a four-lane,urban, undivided roadway, traditional improve-ments include constructing a raised median or acenter TWLTL. Both alternatives, however, involvewidening the roadway, which is costly and some-times impractical.
Converting a four-lane, undivided roadway to threelanes with a center TWLTL can have several advan-tages. Compared to other improvements thatinvolve widening the roadway, they
• are relatively inexpensive,
When are three lanesbetter than four?
• generally have less impact on adjoiningproperty, and
• interrupt traffic for a shorter time duringconversion.
Because the turning lane is reserved for left-turningtraffic, a three-lane roadway can improve sightdistance for turning vehicles and eliminate lanechanges to avoid left-turning vehicles.
Not for every roadwayThe study cautions, however, that converting afour-lane, undivided roadway to a three-lane road-way with TWLTL is not the solution for everyurban corridor. For example, it may be a reasonablealternative only if operational impacts (e.g., decreasein average travel speed) are locally acceptable.
Little research had previously been done on opera-tional impacts of four-lane to three-lane conver-sions. In this study, in addition to case studyanalyses of conversions in Iowa and elsewhere,researchers used simulation software to conduct a“sensitivity analysis” of various factors affectingaverage arterial travel speeds on three-lane and four-lane, undivided roadways.
The study concludes with a thorough discussion of anumber of factors that must be considered to deter-mine when a four-lane-to-three-lane conversion isan alternative improvement:
• roadway function/environment,
• traffic volume and level of service,
• turn volumes/patterns,
• frequently stopping/slow-moving vehicles,
• crash types and patterns,
• pedestrian/bicycle activity,
• right-of-way acquisition costs, and
• general roadway characteristics.
The guidelines presented in the study help ownersdetermine when this option might be included forfurther study in the alternative improvement com-parison stage. The project report is online atwww.ctre.iastate.edu/reports/4to3lane.pdf. •
Editor’s note: This article was originally published inthe August 2001 issue of CTRE en route, the newslet-ter of the Center for Transportation Research andEducation, Iowa State University.
An award-winningconversion in SiouxCenter left room forparallel parking.Photos courtesy of theIowa DOT.
Because the turninglane is reserved for
left-turning traffic,a three-lane road-way can improvesight distance for
turning vehicles andeliminate lane
changes to avoidleft-turning vehicles.
7 SEP–NOV 2001
ABOUT 25 PERCENT of fatal crashes in Iowa involve asingle vehicle that runs off the road; nationally, thisis the primary type of crash in rural areas.
When a vehicle leaves the road, drop-off or ruttingat the pavement edge can contribute to the driverlosing control. A significant difference in elevationbetween the shoulder and pavement may cause thedriver to overcorrect as he or she steers back ontothe roadway, sending the vehicle into the opposinglane where it may spin out or hit an oncomingvehicle. Properly maintaining pavement edges andshoulders can help prevent such crashes, improvingmotorist safety and reducing tort liability claims.
CausesSeveral factors can cause or exacerbate edge drop-offor rutting:
• erosion caused by surface drainage runoff, bywind, or by wind currents created by large,fast-moving commercial vehicles
• settlement of the shoulder or degradation ofshoulder granular material
• high traffic volumes, particularly heavycommercial traffic
• off tracking by wide vehicles
The most serious shoulder deterioration occurs inthe first two feet from the pavement edge.
Certain locations along roads with earth or granularshoulders may be especially prone to edge rutting.Steep hills, the low side of super elevated curves, andintersections commonly exhibit more severe edgerutting than relatively flat, straight locations.
Edge drop-offs also occur during asphalt overlayoperations. The Iowa DOT has responded to thisproblem with design procedures that avoid signifi-cant edge drop-offs adjacent to open traffic lanesduring overlay operations. Local agencies may wantto include the use of sloped fillets along the overlayedge, along with shoulder rehabilitation, in everyoverlay contract.
Although pavement edge drop-off is most commonwith unpaved shoulders, settlement of pavedshoulders can also result in a difference in elevationbetween the shoulder and adjacent pavement.
To pave or not to pave the shoulder?Almost exclusively, Iowa’s lower volume, local andstate rural roads have earth or sod and granular sur-faced shoulders. Unless the topography promotes
Preventing dangerousedge drop-offs
A dangerous combination ofpavement edge rutting andshoulder degradation
edge rutting, a good quality earth or sod shouldercan provide excellent service on these roads.
The Iowa DOT specifies paved shoulders only onvery high-volume and Interstate roadways. Specsinclude a 14-foot wide paved traffic lane that, whenstriped for a conventional 12-foot wide travel lane,provides a two-foot wide paved shoulder.
Maintenance suggestionsPavement edge drop-offs of three to four inches ormore are generally considered unsafe. Iowa DOTmaintenance standards are more stringent, requir-ing corrective action when drop-offs approach twoinches.
Include shoulder maintenance in your regular main-tenance schedule. These activities should include
• regularly repairing bituminous shoulders,
• sealing edge ruts, and
• replacing aggregate and blading unpavedshoulders.
At locations prone to rutting or erosion, considerinstalling low-cost asphalt widening units, approxi-mately two feet wide. This improvement can bemade by agency maintenance staff on a flexibleschedule and can significantly reduce future mainte-nance needs in these often troublesome locations.
For more informationContact Safety Circuit Rider Tom McDonald,515-294-6384, [email protected].
Also, see The Elimination or Mitigation of HazardsAssociated with Pavement Edge Dropoffs DuringRoadway Resurfacing (P1001), an AAA Foundationfor Traffic Safety publication, and the Iowa DOTshoulder maintenance standard. To borrow thesepublications, contact Jim Hogan, CTRE’s librarycoordinator, 515-294-9481, [email protected]. •
8 SEP–NOV 2001
Iowa’s supplement to the millennium MUTCD(left) addresses issues of particular importance toIowa’s city and county road departments.
The Iowa DOT will mail copies of theofficial millennium edition of the MUTCD(right) to Iowa cities and counties this fall.
See the conference calendar onpage 11 for dates and locationsof MUTCD training workshopsscheduled in Iowa during fall2001.
Tom McDonald, Safety Circuit Rider
Editor’s note: This article is part of a series introducinga new resource: Iowa Traffic Control Devices andPavement Markings: A Manual for Cities and Coun-ties. The manual was funded by the Iowa HighwayResearch Board (TR-441) and supplements theManual on Uniform Traffic Control Devices(MUTCD). For information, contact Jim Hogan,library coordinator, 515-294-9481,[email protected], or Tom McDonald, Safety CircuitRider, 515-294-6384, [email protected] is online, www.ctre.iastate.edu/pubs/itcd/.
IN RURAL IOWA, it’s relatively common to findbridges and other structures that are narrower thanthe roadway. One-lane bridges and culverts canpresent particular safety concerns and traffic controlchallenges.
Signing and marking reduced-width structuresIowa’s new manual for cities and counties presentsseveral straightforward options for signing andmarking narrow and one-way structures, particularlyon paved roads, in Section C11, “Narrow Bridgesand Culverts.” For example, the manual describesthe appropriate use of signs illustrated at left.
Accommodating farm equipment on narrowstructuresWide agricultural equipment crossing narrow
Highlights fromIowa’s supplement to the MUTCD
structures can damage signs, markers, and guard-rail, reducing safety and increasing maintenancecosts.
Several signing options that accommodate wideequipment are also described in Section C11 ofIowa’s manual. These options include
• installing flexible supports,
• installing markers on one side of the structureonly, and
• reducing sign mounting height.
Tapering the roadwayA tapered pavement or roadway edge can be used toguide drivers away from hazardous obstacles in thearea of a narrow structure. Section C11 of Iowa’smanual recommends minimum taper lengthsaccording to operating speeds.
For more informationAn innovative feature for bridges and other struc-tures, developed in Des Moines County anddescribed on the following page, could be particu-larly useful on narrow structures.
Sections 2C.13 through 2C.15 of the Manual onUniform Traffic Control Devices (MUTCD) presentseveral signs that can be installed to warn approach-ing drivers of narrow structures. Part 3 of theMUTCD contains specific recommendationspertinent to marking narrow pavements. •
W5-1
W5-3
W5-2a
W5-2
9 SEP–NOV 2001
THE FIRST ANNUAL “Build a Better Mousetrap”competition, held September 5 during the IowaMaintenance Training Expo, attracted severalcontestants. Six winners were chosen:
• Quick Snow Fence Roller, Joe Hodapp,City of Ankeny
• Limb Lopper, Mark Fee and Timothy VanRoekel, Marion County
• Concrete Trailer, Public Works Department,City of Clive
• Telescoping Bridge Rail, Tom Watts andEvan Walker, Des Moines County
• E.Z. Rack, Pat Zimmerman, Johnson County
• Liner Installation Tools, Culvert and DrainageCrew, Johnson County
The “mousetraps” were judged by five people, twofrom cities, two from counties, and one from theIowa DOT, according to the following criteria:
• The innovation serves a purpose and ispractical.
• It applies to all levels of government (city,county, and state).
• It saves time or cost in operations.
• Others could likely build a similar device.
• It performs well.
• It shows originality and ingenuity.
• The judge would consider doing it himself.
One of the competition organizers, Duane Smith,associate director for outreach at CTRE, was pleasedby the variety of competition submissions. It wasclear to him that the contestants “were proud andenthused” about their entries. Smith says the contestwill be continued next year. He thinks it could havetremendous participation in the years to come.
Al Olson, public works administrator for the City ofAnkeny and organizer of the contest judging(though he was not a judge), sees the competition asa way to encourage innovation among employeesand build camaraderie within an organization. Henoticed many people watching the “mousetrap”demonstrations and thinks they prompted people tothink about other ways of doing things.
Olson anticipates that Ankeny employees, who hesays “can put square pegs into round holes,” will
Better mousetraps abound!
A winning mousetrap:telescoping bridge rail
WHEN FARMERS need to move their wide farm equipment across a bridge, they mayunintentionally bend or break bridge rails and signs. Des Moines County mainte-nance workers Tom Watts and Evan Walker developed a telescoping bridge railsystem that permits lowering bridge rails and allows sign or object markerposts tobe temporarily removed so farmers can pass without causing any damage.
Square tubing is attached to the bridge with smaller tubing inserted inside. Pinsand bolts are used for stops, and light chain is attached to prevent loss. The bridgerails cannot be lifted out of the brackets, only lowered. For the railing, chain isinserted in PVC pipe between the upright posts.
For bridges where this kind of railing system cannot be used or is unnecessary, thepost system is used for the signs or object markers at both ends of the bridge.
Watts says the system performs very well and lowers the county’s maintenancecosts. Farmers are happy that they don’t cause any damage to get across a bridge.Vandalism has not been a problem.
For more information about telescoping bridge rails, contact Tom Watts or EvanWalker, Des Moines County Secondary Roads Department, 319-753-8154. •
have something to enter every year. He hopes otherorganizations will encourage their employees toparticipate, too. •
Tom Watts (left)installs a telescop-ing bridge rail ona Des MoinesCounty bridgeon a granular-surfaced road.
Posts for signs and object markers can be tempo-rarily removed (right) so farmers can cross the
bridge without causing damage. Photos courtesy ofDes Moines County Secondary Roads Department.
11 SEP–NOV 2001
conferencecalendar
Decmber 2001
November 2001
October 200123 Multidisciplinary Safety Teams Peer Exchange Des Moines Tom McDonald
(in conjunction with ITCSA Conference) 515-294-6384, [email protected]
23–24 ITCSA Conference Des Moines Sharon Prochnow515-294-3781, [email protected]
30 MUTCD Training Ames Duane Smith515-294-8817, [email protected]
31 ASCE Transportation Conference Ames Jim Cable515-294-2862, [email protected]
31–Nov 1 Traffic Signal Maintenance and Management Ames Duane Smith515-294-8817, [email protected]
1 Better Concrete Conference Ames Jim Cable515-294-2862, [email protected]
5 MUTCD Training Amana Duane Smith515-294-8817, [email protected]
5 ASCE Structural Engineering Conference Ames Jim Cable515-294-2862, [email protected]
6 MUTCD Training Bettendorf Duane Smith515-294-8817, [email protected]
7–8 Traffic Signal Maintenance and Management Bettendorf Duane Smith515-294-8817, [email protected]
14 Concrete Chemistry, Microstructure, Ames Harold Smithand Performance Workshop 515-294-4218, [email protected]
14–16 Fall ISAC Des Moines Duane Smith515-294-8817, [email protected]
3–7 Math Fundamentals Ames Duane Smith515-294-8817, [email protected]
11–13 Iowa County Engineers Association Conference Ames Jim Cable515-294-2862, [email protected]
18 FHWA Concrete Admixture Workshop Ames Harold Smith515-294-4218, [email protected]
December 18, 2001Ames, Iowa
City, county, and state engineers, consultants,contractors, and concrete producers involved inpavement quality control and mix design willbenefit from this event. The workshop will provideup-to-date information and lessons about chemicaladmixtures, which are integral components ofmodern concrete mixes.
Topics will include
• fundamentals of concrete admixtures
• field experiences and future needs
• water reducers, including self-compactingconcrete
Want more informationabout any of the eventslisted here? Check outour reformatted onlineconference calendar, anew, cooperative serviceprovided by Iowa StateUniversity’s Depart-ment of Civil and Con-struction Engineeringand CTRE:www.ctre.iastate.edu/calendar/. •
Moreconferenceinfo online
FHWA Concrete Admixture Workshop
• shrinkage-reducing admixtures
• accelerating and retarding admixtures
• admixtures that mitigate corrosion
• special admixtures, including colors
Registration information is in the mail and online atwww.ctre.iastate.edu/calendar/.
For more information, contact Harold Smith,training and public works engineer, Center forPortland Cement Concrete Pavement Technology,Iowa State University, 515-294-4218,[email protected], or see www.ctre.iastate.edu/calendar/. •
Iowa State UniversityCenter for Transportation Research and EducationISU Research Park2901 S. Loop Drive, Suite 3100Ames, IA 50010-8632 ExtensionLocal Transportation
P 486-0524
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2001 “roadeo” winners
Iowa’s annual Snow Plow and Motor Grader “Roadeos” wereheld at the Iowa State Center in Ames on September 4, 2001.
Chris Archer of Pocahontas County took top honors in themotor grader competition, followed by Sac County’s RickSackett in second place and Pocahontas County’s KenHoopingarner in third.
First place in the snow plow competition went to the Ankenyteam, Charles Cole and Dennis Gaulke. Second place went toDan Arndt and Hobart Schoonover of Polk County, andthird to Mark Goins and Greg Householder of Ankeny.
Competitors in both events took a written exam and navi-gated a snow plow or motor grader through an obstaclecourse.
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Top, left to right: K. Hoopingarner; Ron Dirks, PocahontasCounty, motor grader competition organizer; R. Sackett; C. Archer
Bottom, left to right: D. Arndt; H. Schoonover; C. Cole; D. Gaulke;Bret Hodne, City of West Des Moines, member of Expo steering
committee; Al Olson, City of Ankeny, chair of Expo steering committee;G. Householder; M. Goins.
