Partnership Between the Greater New Orleans Expressway Commission and the National Weather Service Forecast Office in Slidell, Louisiana
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PARTNERSHIP BETWEEN THE GREATER NEW ORLEANS EXPRESSWAY COMMISSION AND THE NATIONAL WEATHER SERVICE FORECAST OFFICE IN SLIDELL, LOUISIANA Alan Johnson, Paul Trotter and Freddie Zeigler NOAAlNational Weather Service Forecast Office Slidell, Louisiana Abstract span has been rammed by marine traffic about sixteen times. Also, there have been incidents where vehicles have For the safety of life and property in southeast been knocked off the bridge into the lake. Louisiana in hazardous weather situations, a strong part Applying local forecast techniques using the latest nership has developed between the NOAA/National numerical guidance, enhanced technology, automated Weather Service Forecast Office in Slidell, Louisiana and and manual surface observations, NWSFO Slidell has the Greater New Orleans Expressway Commission. This significantly improved the forecast lead time for the report outlines the products developed by the partnership development of dense fog over the tidal lakes. Figure 1 concerning dense fog events affecting the traffic on the illustrates the typical synoptic pattern conducive to Lake Pontchartrain Causeway, the longest bridge in the dense sea/lake fog development. The motorists can be world. notified by using the Internet to access Web site: www.thecauseway.com or the NWS Web site: 1. Introduction www.srh.noaa.gov/ix. The latest dense fog advisories are given in the Hazardous Weather Outlook (HWO) twice The Lake Pontchartrain Causeway in Louisiana is the daily and updated as needed. This product, issued rou longest bridge over water in the world (38,422 km; 23 tinely at 0630 local time and 1100 local time daily, lists miles 1,538 yd). The first span opened to the public in weather hazards which may cause visibility problems for 1956, the second in 1969. It allows one-way driving safe motorists during the following 24-hour period. It is also ty on straight, two-lane railed surfaces 80-ft apart con issued on the NOAA Weather Radio (NWR) as well as to nected by seven crossovers to provide pullover areas for the news media. In the short term, the Causeway pro vehicle emergencies. Over 30,000 commuter vehicles vides current weather information to the motorists on the make a round-trip crossing of the lake daily. The bridge variable message signs approaching the bridge as well as connects Jefferson Parish on the South Shore and Saint the Causeway's Information Advisory Radio Station (a Tammany Parish on the North Shore. The low-power radio station at 1700 AM). NOAAlNational Weather Service Forecast Office Another purpose of this study was to show how public (NWSFO) in Slidell, Louisiana has developed a partner awareness campaigns have been provided. This has been ship with the Greater New Orleans Expressway done through the publishing of a fog brochure. The Commission in order to strive to give the Causeway brochure was designed and developed as a coordinated Commission more precise forecasts and advisories. effort between the Slidell NWSEO and the Causeway Consequently, products developed can be used to assist in Commission of Greater New Orleans. This brochure preparation for such significant weather events as high informs motorists of the safety procedures for crossing winds across the lake which impede certain vehicles such the world's longest bridge. See Fig. 2 for picture of the as recreation vehicles, glass transporters and motorcycles Causeway. as they try to make their way across the bridge. Other types of inclement weather that affect bridge operations 2. Partnership between NWSFO Slidell and the Greater are dense fog, severe thunderstorms, heavy rain, hail New Orleans Expressway Commission storms, hurricane conditions, waterspouts and winter freezes. In the past several years, a unique partnership has One of the purposes of this study is to show how the been developed between the NWSFO Slidell and the local NWSFO in southeast Louisiana has used local Greater New Orleans Expressway Commission. Aided by research to develop forecast techniques for the formation the research and development of a "fog decision tree" by of dense fog over the tidal lakes. Safety of motorists across several NWSFO LIX forecasters in the early 1990's, the the Causeway is extremely important. The Causeway lead time for forecasting dense fog over the tidal lakes Police Department is greatly concerned with sudden and has been significantly improved. Using the latest rapid weather changes which affect visibility as well as enhanced technology, numerical guidance, observations, the ability to control high profile vehicles. Since the bridge satellite imagery, and sea surface temperatures, forecasts initially opened in 1956 with two lanes across the lake, the for surface visibility can be made several days in 54 Volume 28 December 2004 55 ' 11 .Ill I :. I _ • A I I I --/ Fig. 1. Typical synoptic pattern during return flow in the Northern Fig.3. These message signs are used to warn motorists of poten gulf in the wintertime. tial upcoming roadway conditions. • GREArER NEW ORLEANS : : ]'01.;: 0; EXPRESSWAY . • , COMMISSION , " " Tnlffic Munag:~ll\l!n l & I., Fog Abmement System I : THE 1970'5 f. ·1, I • ; : Polko! I , 1 1 Fig. 4. Initial convoy system used by the Causeway police in the 1970's. Fig. 2. There has been several improvements concerning safety on the Causeway since the first span of two lanes was opened in 1956. In 1969, another span of two lanes was opened giving two ing them of developing weather conditions. During the lanes in each direction. The picture above shows the Causeway wintertime, dense fog is likely not only over the cooler across Lake Pontchartrain looking north. shallow tidal lake waters, but also over adjacent land areas especially when the wind is light. advance. The Causeway Police Department can then use High winds, hurricane conditions, severe thunder this information for staffing purposes especially for the storms, hailstorms, waterspouts, heavy rains, and freezes onset of the dense fog when convoying of motorists might are also weather phenomena which may affect travel become necessary. over the Causeway. However, occurrences are a much Dense fog over the tidal lakes is the most important smaller percentage when compared to the dense fog dur weather parameter motorists have to deal with during ing the winter months of November to March. There are the year. That is, seasonally, dense fog events may last for usually about 10 to 15 episodes of significant fog affecting several days except for minor improvement in visibilities travel over the world's longest bridge during a season. during the mid-afternoon into the evening hours. Thus, convoying may become necessary for both morning and 3. Methodology Used by Causeway Police In Reducing afternoon commuters. Loss of Life and Property during Adverse Weather In addition to the fog brochure which was made available for the first time at the beginning of the fog According to Lambart (1991) there has been several season in late 2001, several ads have been published in improvements concerning safety on the Causeway since the Times Picayune of New Orleans newspaper and in the first span of two lanes was built and opened in 1956. the New Orleans City Business Magazine. These ads In 1969, another span of two lanes was opened giving two advise motorists of helpful guidelines to follow during lanes in each direction. The Causeway police have estab fog conditions. lished an excellent rapport with the commuters by The Slidell NWSFO has direct contact with the exchanging roadway information over citizen band radios Causeway Police Department. Besides issuing a Dense and cellular phones and, and of course, the AM broadcast. Fog Advisory to the public and news media, coordination Safety enhancements were made in 1984 with the instal calls are made to the dispatchers at the Causeway advis- lation of the Motorist Information System (MIS). These 56 National Weather Digest ''I 1 G REATER NEW O RLEANS Poll':.ll EXPRESSWAY i ·'" 1 C O MMISSION ~ I, Tram e Management II & I I.~ ' ; Fog Abatement System I I ~ " I : "Ul T HE LATE 1980's , ,I I 1 1 !~ r t ' 11'011:1; 1:,.] 1 I' oll ~c I 1 .1- Fig. 5. Convoy system used in the 1980's utilizing a lead car in the front and one in the back. Fig. 7. Fog abatement sign configuration illustrates the view from ground level to what motorists would encounter when controls have been put in place on the bridge. 1 I GREA~i~~is~~:~EANS I· ,I C O MMISSION 16r-_______--, I' ,I: : 70 r-- ------, ~ . 'I r\.lkc Tra me M anagement NO Ft){i f• • ,. Fog A batem ent System I! ~ : :: 6 mi 13200· 9{)On 1111 '. & . I" IHI I 'I r nli..:c 1990 TO THE liJ PRESENT 1 lU I :.~ ~ mi I.JR!iO IIl j !' 'I Wind ~ PATCIIY j .... l P.. HCIIY i::1 . ~;~I;S ) 6 r OG rnC'j I, 'I: : I)o l=----~ I: : I Pull" <2ml ,. 1: I (.120(lml i I Pa lloo IfIO '---'---'_-'----'-_-'--.Ll I o J 2 3 4 I~ l:'i IS J T" - Td ( 'C) Tw-Ta ( C) Advecfio n (enlporation/steam) Fog Wlll'm Advcction(cooli ng) Fog Fig. 6. System used in the 1990's to present time by Causeway police (riding herd) to prevent motorists from passing (used when visibility is below 500 feet). NOI:O("j .' e " ~ " I>mi Ta-TII "' : , ,, ,,,i Ta - Ttl ~l :r)O . ~ 1!1l ( ~~OO-_Il\I(IO! are twelve variable message signs (Fig. 3) which are used rC) : rq , p.\T(m 1';\f('JI\' rm, to warn motorists of potential upcoming roadway condi FOG tions. As a toll facility, it is essential to avoid, if possible, -. ':-m,..,i\3""l ll(J,.-.......' "\ a disruption in service of the daily commuters.