Improper pavement drainage cause wrecks. Water ponding in travel lanes of high-speed, high-volume highways create a danger to vehicles passing through the water... a vehicle hydroplanes, crosses the centerline of the highway and crashes into an oncoming vehicle.
Motorists simply do not anticipate water ponding on our modern highway systems. The lucky ones hydroplane through the water, recover from the loss of tire/pavement contact and continue on their journey. No vehicles or obstacles happen to be in their path of travel.
The unlucky ones run-off-the-road and collide with trees or obstacles along the side of the roadway or cross the centerline into oncoming traffic. A traveling motorist does not expect water to be in their path of travel. The average driver has no idea what causes hydroplaning or what to be aware of to avoid a hydroplaning accident.
In this article I am going to point out four (4) areas of the highway that are subject to creating hydroplaning conditions. Certain areas of our highways have a higher risk than others. These are 4 of the most critical locations on any roadway.
Pavement drainage in vertical sags is one of the highest risk areas on any roadway.
One of our cases involved an accident which killed several young adults. The accident occurred in the vertical sag of the highway. The young driver and 3 of his friends were returning to school in the middle of the day. The driver was driving under the speed limit of the highway.
A sag vertical curve is the low area between two hills. Of course, the top of the hill on a highway is called the crest vertical curve.
Storm water flowed from the crest of vertical curve toward the sag of the vertical curve. Water flows to the sag from two directions. Water that cannot get off the pavement surface reaches the bottom of the hill, increases in depth and creates the conditions for hydroplaning.
In our case, the tire paths had failed and created depressions, which allowed even more water to flow to the bottom of the vertical curve.
To make matters worse, an office building construction project was under construction and the driveway entrance was being constructed at the sag of the vertical curve. The buildings were at a higher elevation than the highway and the grade of the driveway increased from the highway to the office building parking lot. During rains, water from the parking lot flowed to the highway. Now, water came from three directions to the sag in the highway.
So when the storm water reached the bottom of the hill, the water could not flow from the roadway. The water would pool.
The students traveling to school hit the pooling water and their vehicle hydroplaned. The vehicle crossed the centerline of the highway and crashed into an oncoming van. The four young adults were killed in the impact.
A similar accident I reconstructed involved the accumulation of excess dirt and debris on the grass shoulders of the roadway. Again, the shoulder build-up was in the sag of the vertical curve. The elevation of the grass shoulders was higher than the pavement, which caused storm water pool in the roadway. This created conditions for cars to hydroplane.
Approximately 100 yards from the vertical sag was an access road to a dirt pit. Dump trucks were loaded with dirt in the pit. They traveled from the access road exit onto the highway and from there to their destination for the dirt.
Over a period of several months, the loose dirt from the dump trucks would fall onto the highway. The loose dirt from the dump trucks would be blown off the truck onto the pavement surface as the truck increased its speed. The loose dirt would be blown from the travel lane to the grassed shoulder by vehicles using the highway.
The pavement drainage during rain storms flowed to the bottom of the sag of the vertical curve. The storm water could not flow from the roadway until its depth became greater than the grass shoulders. The water would get several inches deep.
The local drivers knew to slow down. But of course along comes a driver that does not slow down, hits the standing water, hydroplanes and crosses the centerline into an oncoming vehicle. The driver of the oncoming car was killed.
Pavement drainage must be monitored by maintenance personnel and problem areas addressed.
Careful evaluation of vertical sags and build-up of grassed shoulders should be made regularly. These are areas of potential hydroplaning wrecks during rain events.
Hydroplaning caused by roadway defects
Qualifications of a good hydroplaning expert
Hydroplaning article written by Elvin Aycock for the American Institute of Hydrology.
Ruts cause hydroplaning where the asphalt and the subgrade has failed.
Hydroplaning on roadways while transiting from superelevation to normal crown
Pavement drainage can be a problem in vertical curve sags and in transitions from superelevations to tangent sections.
More pavement drainage problems occur when the centerline crown is destroyed and superelevation transitions hold water.
Mtiririko usiofaa wa maji kwenye barabara husababisha majanga. Maji katika barabara kuu za mwendo wa kasi, zenye wingi wa magari, huunda hatari kwa magari yanayopita kupitia maji, gari la maji, linapita katikati ya barabara kuu na kugonga gari linalokuja. Madereva wa magari hawataraji kwamba kuna vidimbwi vya maji kwenye barabara zetu za kisasa. Wale wenye bahati hupanda ndege ya majini kupitia maji, hupona kutokana na kupoteza mawasiliano ya tairi na barabara na kuendelea na safari yao. Hakuna magari au vizuizi vinavyotokea katika njia yao ya kusafiri. Watu wasio na bahati hukimbia barabarani na kugongana na miti au vizuizi kando ya barabara au kuvuka mstari wa katikati katika trafiki inayokuja. Dereva anayesafiri kwa gari hataraji kwamba maji yatakuwa njiani. Dereva wa kawaida hana wazo la kisababishi cha hydroplaning au nini cha kuwa na ufahamu wa kuepuka ajali ya hydroplaning. Katika makala hii, tutazungumzia maeneo manne ya barabara kuu ambayo yanahusika na kuunda hali ya hydroplaning. Sehemu fulani za barabara zetu kuu zina hatari kubwa kuliko nyingine. Hizi ni sehemu nne muhimu zaidi kwenye barabara yoyote. Mtiririko wa maji kwenye barabara katika sehemu zenye mteremko ni mojawapo ya maeneo yenye hatari zaidi kwenye barabara yoyote. Mojawapo ya kesi zetu ilihusisha aksidenti ambayo iliua vijana kadhaa. Aksidenti hiyo ilitokea kwenye mteremko wa barabara kuu. Dereva huyo na marafiki wake watatu walikuwa wakirudi shuleni wakati wa mchana. Dereva huyo alikuwa akiendesha gari kwa mwendo ulio chini ya kiwango cha mwendo wa barabara kuu. Mzunguko wa wima wa sag ni eneo la chini kati ya vilima viwili. Kwa kweli, kilele cha kilima kwenye barabara kuu huitwa mteremko wa mteremko wa kilele. Maji ya dhoruba yalitiririka kutoka kwenye kilele cha mteremko kuelekea sehemu ya chini ya mteremko huo. Maji hutiririka kuelekea eneo hilo kutoka pande mbili. Maji ambayo hayawezi kutoka kwenye uso wa barabara hufikia chini ya kilima, huongezeka kwa kina na kuunda hali ya hydroplaning. Katika kesi yetu, njia za tairi zilikuwa zimeshindwa na kuunda maporomoko, ambayo yaliacha maji zaidi kutiririka chini ya mviringo wa wima. Jambo la kushangaza zaidi ni kwamba, ujenzi wa jengo la ofisi ulikuwa ukiendelea, na mlango wa kuingia ulikuwa ukiwekwa kwenye sehemu ya chini ya mteremko wa mteremko. Majengo yalikuwa juu zaidi ya barabara kuu na kiwango cha barabara ya kuendesha gari kiliongezeka kutoka barabara kuu hadi mahali pa kuegesha magari ya jengo la ofisi. Wakati wa mvua, maji kutoka kwenye mahali pa kuegesha magari yaliingia kwenye barabara kuu. Sasa, maji yalitoka pande tatu hadi kwenye bonde la barabara kuu. Kwa hiyo, wakati maji ya dhoruba yalipofika chini ya kilima, maji hayangeweza kutiririka kutoka kwenye barabara. Maji yangejaa. Wanafunzi waliokuwa wakienda shuleni walianguka kwenye maji na gari lao likaporomoka. Gari hilo lilivuka katikati ya barabara kuu na kugonga gari dogo lililokuwa likija. Vijana hao wanne waliuawa wakati wa mgongano huo. Ajali kama hiyo niliyoigiza ilihusisha mkusanyiko wa uchafu na mabaki mengi kwenye mabega ya nyasi ya barabara. Tena, mabega kujengwa-up ilikuwa katika sag ya curve wima. Urefu wa mabega ya nyasi ulikuwa juu kuliko barabara, ambayo ilisababisha dimbwi la maji ya dhoruba kwenye barabara. Hilo lilifanya iwezekane kwa magari kusafiri kwa ndege ya majini. Karibu mita 100 kutoka kwenye mteremko huo kulikuwa na barabara ya kuingia kwenye shimo la udongo. Malori ya kutupa takataka yalikuwa yamejaa udongo ndani ya shimo hilo. Walisafiri kutoka njia ya kuingia kwenye barabara kuu na kutoka hapo hadi mahali walipokuwa wakienda kwa ajili ya uchafu. Kwa muda wa miezi kadhaa, udongo uliotoka kwenye malori hayo ulipanda kwenye barabara kuu. Uchafu uliokuwa umechukuliwa na malori hayo ulipelekwa kwenye barabara wakati malori hayo yalipokuwa yakiongeza mwendo. Udongo uliokuwa umefungwa ungepigwa na upepo kutoka kwenye barabara ya kusafiri hadi kwenye mabega yenye nyasi na magari yaliyokuwa yakitumia barabara kuu. Mtiririko wa maji ya barabara wakati wa dhoruba za mvua ulitiririka hadi chini ya mteremko wa mteremko wa wima. Maji ya dhoruba hayangeweza kutiririka kutoka kwenye barabara hadi kina chake kiwe kikubwa kuliko mabega ya nyasi. Maji yangekuwa na kina cha sentimeta kadhaa. Madereva wa mahali hapo walijua jinsi ya kupunguza mwendo. Lakini kwa kweli, dereva ambaye hakuzima, anapiga maji, anapanda ndege na kuvuka mstari wa katikati na kuingia kwenye gari linalokuja. Dereva wa gari lililokuwa likija upande ule mwingine aliuawa. Mtiririko wa maji ya barabara lazima ufuatwe na wafanyakazi wa matengenezo na maeneo ya tatizo yanayoshughulikiwa. Tathmini ya makini ya sags wima na ujenzi wa mabega nyasi inapaswa kufanywa mara kwa mara. Hizi ni maeneo ya uwezekano wa hydroplaning wrecks wakati wa matukio ya mvua. Hydroplaning husababishwa na kasoro za barabara sifa za mtaalam mzuri wa hydroplaning Hydroplaning makala iliyoandikwa na Elvin Aycock kwa Taasisi ya Amerika ya Hydrology. Ruts husababisha hydroplaning ambapo lami na subgrade imeshindwa. Hydroplaning juu ya barabara wakati wa kuhamia kutoka superelevation kwa kawaida taji pavement mifereji inaweza kuwa tatizo katika wima curve sags na katika mabadiliko kutoka superelevations kwa sehemu tangent. Matatizo zaidi ya mifereji ya barabara hutokea wakati taji la katikati linaharibiwa na mabadiliko ya juu ya juu yanaweka maji.