KHAO SAT TRANG THAI NHl|T CUA MAT DITffNG BE TONG XI MANG BANG PHUONG PHAP PHAN TU HUU HAN
PGS.TS TRJNH V A N QUANG
DHGTVT-HN
Tom tat: Bai bao trinh bay each sit dung phuang phap phan tis hu'u han de danh gia trang thai nhiet cua mat dudng be tdng xi mang dudi tac ddng cua thay ddi nhiet dp khdng khf va biic xa mat trdi.
Abstract: The paper presents the way to use the finite element method to study thermal state of the concrete surface of the road under impact of the varying air temperature and solar radiation.
I. Oi^T VAN OE :
Bai toan trang thai nhiet mat dudng de'n nay da cb nhieu tac gia nghien ciiu [1],[2],..Vdi muc dfch md rpng cac phuang phap tfnh nhiet, bai vie't trinh bay each su dung phuang phap (pp) phan ti} hu'u han (PTHH) trong tfnh nhiet, de xac djnh nhiet dp va dua ra cac nhan dinh ve trang thai nhiet cua tam be tdng (BT) dudi tac dpng cua cac yeu td khf hau thay ddi.
II. PHU-QNG PHAP KHAO SAT
2.1. Gidi han bai toan , du lieu ban dau
+ Khao sat ta'm BT day L=0,3m, dai va rbng 7,5m dat tren nen da't; BT cd he sd dan nhiet k=1,265W/m°C; khd'i lupng rieng P =2200kg/m'; nhiet dung rieng c=1215J/kg°C; mat tren toa nhiet vdi khdng khf vdi h=7,89W/nf°C, va hap thu tia mat trdi vdi 8 =0,65. Nen da't cd: kN=0,52W/m°C; P^g
=2050kg/m'; CN=1840J/kgdd. 6 dp sau du Idn nen dat cd nhiet dp khbng ddi la 28,8°C. Nhiet dp khdng khf T|^, biic xa mat trdi E trong ngay thang 6 thay ddi theo sd lieu cua nganh khf tuang, bang 1, tdc dp gid trung binh w = 2,4 m/s.
Bang 1
Gia
T,(*C) KIWm't Glor T,("C]
K(WW)
5 26,3 0 17 31,3 203,5
6 26,5 34.89 18 30,2 58,15
7 27,2 209,3 19 29,6 0
6 27,7 407.0 20 28,8 0
9 28,5 610,5 21 28,4 0
10 29,4 779,2 22 28,2 0
11 30,1 895,5 23 27,6 0
12 30,7 930,4 24 27,2 0
13 31,3 872,2 1 27,0 0
14 31,8 744,3 2 26,8 0
15 32,0 593,1 3 26,5 0
16 31,7 401,2 4 26,4 0
Truyen nhiet qua tam BT cd be day nho han rat nhieu so vdi be rdng va dai, dupc md ta bdi phuang trinh vi phan dan nhiet mpt chieu:
dT , 5 ' T P.C = k r- (1)
vdi x la be day tfnh tCr mat tren. Oieu kien bien toa nhiet va biic xa tai mat tren x=0, la:
- k ^ = q + h ( T ^ - T j (2) cTT
Vdi T, T^n va T|^ tuang iing la nhiet dp trong tam be tdng, nhiet dp be mat va khdng khf (°C), x la thdi gian (s), X la chieu sdu ke t i i mdt tam (m), q ddng biic xa mat trdi (W/m').
2.2. Phuong phap phan t u huu han
1- Rdi rac mien nghiem: Be day tam be tbng duac rdi rac thanh 12 phan t i i (PT) ky hieu, ®,(D,(3) ... moi PT dai la / = 0,3m/12 = 0,025m, va 13 nut ky hieu 1,2,3,...,13. Nen dat chpn mpt PT thii 13, dai /va nut 14, hinh 1.
q . h -
Tx 3 4 .5 9 10 11 12 13 M
Hinh 1. Sa do r&i rac l&p be tong thanh cac PTHH
2- Ham noi suy: Chpn ham bac nhat:
N = [Ni N J = I - -
/ (3)
vdi / la chieu dai cua mpt PT, x la toa dp trong phan tli, nen nhiet dp la T = N^Ti + N^Tj = [ N ] { T } (4);
Tj va Tj la nhiet dp tai hai nut cua PT. Dao ham cua ham ndi suy [B], gradient nhiet dp [g] la
TAP CHI CAU OLfONG VIET NAM
ST ax"
5N dx
"cN, .^
—-T dx '
"3N, 5 N /
dx dx
— ^ T dx '
=;i
CIN : 1 r 1 r 1
-^' =![-! 1]=[B] (5);
l]{^;} = [B]{T} = [g] (6)
4 - Rdi rac theo thdi gian. Cb the rdi rac (11) bang pp Sai phan hu'u han (SPHH) hay PTHH.
a. Rai rac bang pp SPHH. Theo pp SPHH thi
' T ' P + l "T* /
AT (11) trd thanh:
3-Thie't lap phuong trinh ma tran dac trung cua phan t u :
Cd nhieu phuang phap thie't lap Phuang trinh ma tran dac trung cua phan tur. Trong tfnh nhiet, pp Bie'n phan (Rayleigh Ritz) va Galerkin la hai pp quan trpng nhat vi cho ke't qua chinh xac nhu nhau. 6 day chpn pp Galerkin, lay ham trpng sd la ham nbi suy Nj.
Phuong phap Galerkin yeu cau (1) thoa :
]:H
C a2' , a'T OT"!
k — r - p c — dx^ dl
dV = 0 (7)
Lay tfch phan tCrng phan sd hang dau cua (7) cd f N , k A f - V = fN,kdpldydz= fN.k^dS-fk^.^dxdydz
{[€]+^.AT[Kl}{Tr' = {[C]- (1 - yATfKjKT}' + AxlUf r ' + d - « (f I'l 15)
Trong db AT la budc thdi gian iing vdi hai thdi diem lien tie'p p va (p+1); ^ = 0 +1 la tham sd tuy chpn: ^ = 0-rl. Neu lay ^ =1 khdng can dieu kien han che chpn budc thdi gian AT.
b. Rai rac bang pp PTHH: Cd cac pp sd du trpng sd khac nhau de rdi rac (11) theo thdi gian. Dung Galerkin, ham trpng sd la ham ndi suy bac nhat cua thdi gian N .N,=[Np N^^J (16), PP Galerkin yeu cau (11) thoa:
dK^ik) \i ' ydn.) '' \ ' dx { dx dx ' ^ ' S la dien tfch mat ngoai cd ddi luu, biic xa. Oieu kien bien (2) trd thanh:
| N , k £ d S = -|N,qdS-|N,h(T-T,)dS (9)
Thay (4),(8) va (9) vao (7) sap xep lai se dupe : t>.cN,N,)dVpjpl [fk|iJjlV.[(hN,N,)ls{r,(T))=-[N,qdS+[hN,T,dS (IQ)
Viet (10) gpn dang ma tran la :
[ c ] { f } + [K]{T}={f} (11)
(11) la Phuang trinh ma tran dac trung cua phan tl}. Trong do: [C] goi la ma tran nhiet dung,
[C] = [ [ (p.c[Nf [N]}ivJ (12); [K] la ma tran dp ciing,
[K]=|j;(k[Br[B])lV+|(h[Nf [N]}is] (13); {f} |a ve
r^pmf}^w{T^-^^^}^^=«
(17).Thay (4),(5) va (16) vao (17), bien ddi dupe:
AT
-1 1 -1 1 Dan tdi
T"*' I 3
2 I
1 2 J p+1 : p + I (18)
{[C]+AT[K]}T''*' = {[C]-AT[KI}T'' +-[f' H-f *')\T (19)
(19) yeu cau AT phai chpn du nho de nghiem hpl tu. Cb the tim nghiem T"^' tCr (15) ho§c (19)
5 - Tmh cac sd^ hang trong phuong trinh ma tran die trung cua phan tu mot chieu
a. Afa tran nhiet dung phan ttf [C]. Thay cac sd lieu cua be tdng va nen dat tfnh dUdc
vec
td tai nhiet, {f} = - JlNfqdS + ih[NrT^dS ( u ) .
Be tbng : [<^]i-i2 =
Nen dat: [c\.
line, 1113S "
11138 22276
31434 15717' 15717 31434_
(20);
(21)
TAP CHi CAU DLTdNG VIET NAM
b. Ma tran do cting phan tu[K]: - Cac PT 1, 212 va 13 tuang iing la
[4=-
[KU =
[Kl3 =
"l
-
Ak 1
Lk"
1
1 + hA ' 1 - 1
- 1 1
1 - l "
- 1 1
"l 0
0
0 = '58,49 -50,6 -50,6 50,6
" 50,6 - 5 0 , 6 ' - 5 0 , 6 50,6
20,8 -20,8"
- 20,8 20,8
(22) (23)
(24) Vdi A la dien tfch truyen nhiet, A = 1m^
c. Vec taphu tai nhiet {f}:
{f}M (26)
6 - Lip ghep cac phan tu - Ma tran nhiet dung toan he:
lc|-
22276 11138 0 0 O 0 1II3B 12276 11138 0 0 0 0 1113S *iSSl I113S 0 0 0 0 11138 4*SS1 III3S 0 0 0 0 11138 44552 I
11138 44552 11138 0 0 0 0 0 0 III3S 44552 11138 0 0 0 0 0 U 11138 44552 11138 0 0 0 0 0 0 11138 44S32 11138 0 . 0 0 0 0 0 11138 44552 11138 0
1138 44552 11138 0 0 11138 44552 11138 0 0 III38 63710 15717 0 0 1J717 41434
(27)
- Ma tran dp ciing toan he [K], vec ta phu tai tdng {f}, sau khi ap dat dieu kien bien tai Idp nen cd T[sg
=Ti4= 28,8 se dupc cac ma tran (28) va (29) dudi day.
7- Giai he phuong trinh
Vi sd lieu cho theo gid (bang 1), tiic AT = 3600s, nen chpn (15) de giai se thuan tien han (19). TCr (15) suy ra:
{ X r = {[C] +AT[K]}-'*([c]{Tr + A T J f r ) (30) Lay {T}P=0 =28,80C, thay (25),(26) va (27) vao (30), lap trinh va giai (30) tren Matlap qua 192 thdi diem.
Ke't qua dupc lap thanh bang va dd thj.
58 J9 -JO 6 -50.6 101.2 0 -506 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 -S0.6 1012 -50 6 0 0 0 0 0 0 0 0 0
0 0
•506 101.2 -50 6 0 0 0 0 0 0 0 0
0 0 0 -50.6 101.2 -506 0 0 0 0 0 0 0
0 0 0 0 -50 6 101.2 -506 0 0 0 0 0 0
0 0 0 0 0 -506 101.2 - 5 0 6 0 0 0 0 0
0 0 0 0 0 0
•50 6 1012 -50 6 0 0 0 0
0 0 0 0 0 0 0 -S0.6 1012 -506 0 0 0
0 0 0 0 0 0 0 0 -506 101 2 -50.6 0 0
0 0 0 0 0 0 0 0 0 -50.6 101 2 -506 0
0 0 0 0 0 0 0 0 0 0 -506 101.2 -506 0 0 D 0 0 0 0 0 0 0 0 -50 6 71.4
(28)
W=
7.89.T,. + q 0 0 0 0 0 0 0 0 0 0 0 599,04 28.8
(29)
III. KET QUA TINH TOAN VA CAC NHAN XET 3.1. Dien bie'n va thay doi nhiet dp tai 14 nut sau 192 thoi diem
Dien bie'n va thay ddi nhiet dp tai 14 nut sau 192 gid the hien tren hinh 2 va 3. TCf dd rut ra cac nhan xet:
1. Thay ddi nhiet dp theo thdi gian tai 14 nut la 14 dudng dao ddng, gom 8 chu ky tuang iing 8 ngay dem. TCf chu ky 5 trd di, dao ddng trong cac chu ky tuan theo cung mdt quy luat, nhiet dp tai moi nut d cung thdi diem tuang iing trong ngay da hpi tu tdi gia tri dn dinh.
2. Ke tCr chu ky thii nam, cd the chpn nhiet dp tai 24 thdi diem lien tiep de dai dien cho thay ddi nhiet dp trong tam be tdng qua mpt ngay dem dien hinh mua he. O day chpn tCr thdi diem 154 de'n 177.
3.2. Dac tinh thay doi nhiet do trong ta'm be tdng qua mpt ngay dem dien hinh thang 6.
Dac tfnh thay ddi nhiet dp duac bieu thi tren hinh 4 va 5. Cd the rut ra nhan xet sau:
1. Thay ddi nhiet dp tai mat tren cung la ham chu ky, khdng bieu thi la ham sd cosin cua thdi gian, nhung cang vao sau trong tam BT, dang dao ddng nhiet dp cang tien tdi hinh sin.
TAP CHI CAU OaONG VIET NAM
2. Thdi diem nhiet dp dat cue dai cham dan tCr mat tren cung qua cac Idp giCfa, mudn nhat la mat dudi cung. Phan bd nhiet dp tai mpi thdi diem trong ngay ludn la dudng cong, hinh 5.
DIEN BIEN NHIET DO SAU 192 THOI OIEM
Hinh 2. Toan canh diin bie'n nhiet dp sau 192 gid
THAY DOI NHIET DO SAU 192 THOI DIEM
Thoi gian (gio) 150 200
Hinh 3. Thay ddi nhiet dp 14 nut sau 192 gid
Thay dol nhltl do tai 14 dlam Irong moi ngay dam
10 12 15 20 24 1 Thoi gian (gio)
Hinh 4. Thay doi nhiet dp tam BT 1 ngay dem
65- 60- 55-
" 5 0 -
| « -
ito-
z 35-
Phan bo nhlal do tai cac Ihol diem Irong mot ngay dem
' VI tri CSC diam
Hinh 5. Phan bd nhiet dp tai cac thdi diem 3.3. Trao dol nhiet cua ta'm be tong
Trao ddi nhiet cua ta'm BT vdi mdi trudng trong
mdt ngay dem dien hinh the hien tren hinh 6. Cd the thay: Trong mdt ngay dem, tam BT nhan nhiet trong 11 tie'ng, tCf 7h sang de'n 17 h chieu (q > 0), thai nhiet trong 13 tieng, tCf 18h den 6h sang hdm sau (q < 0).
Tdc dp nhan nhiet lang rat nhanh vao budi sang, giam vao chieu. Nhiet nhan Idn nhat luc 11,12 h. Tdc dp toa nhiet toa nhiet ra mdi trudng kha ddng deu.
350 iJ 300 3 250
Luong nhiet trao dot trong t ngay dem cita tam be long
l IIIIDIIIW
15 20 Thot gian (glo)
Hinh 6. Lugng nhiet tam BT trao doi v&i moi trudng trong mot ngay dem
Mien
Thiet dien phSng tn/dc bien djng
Dt/dng cong nhiet (50 thuc T
• / Duong nhi?t dp trung 'j binh tuyen tinh T „
Thiet di^n phang sau bien dang
Hinh 7.
3.4. Nhan djnh ve bie'n dang nhiet cue bp cua
ta'm BT r a. Bien dang nhiet cue bo . Theo ly thuyet bien
dang nhiet [2],[3], khi phan bd nhiet dp la dudng cong, thi trong vat lieu se xuat hien bien dang nhiet cue bo 8 j va ling suat nhiet rieng hj. Neu 8j > z^^h (^Ktii '^
bie'n dang keo tdi han), (hoac 5-r > [6] ([8] la u'ng suat cho phep)), vat lieu se bi ran nut, pha huy. Bien dang nhiet cue bo xac djnh bdi Sj = (3jAT (26); vdi Py la he sd gian nd nhiet, AT la chenh lech nhiet do cue bg:
AT(x) = TJB(X) - T(x) (27); vdi T(x) la nhiet dp thuc, la dudng cong, TJB(X) la dudng nhiet dp trung binh tuyen tfnh, dd la dudng thang song song vdi thiet dien phSng sau bie'n dang [2],[3], hinh 7, xac djnh bdi
^T„ T„
(28);
TAP CHI CAU oaCfNG VIET NAM
T ^ l , Tm2 la *n sd nhiet dp trung binh tuye'n tfnh hai tai mat 1 va 2 cua tam BT. TCr (26) thay, khu vuc cd TJB(X)>T(X), se bj keo, nguac lai, khu vuc cd TTB(X)<T(X) se bi nen, hinh 7.
b. Dac diem cac mien bj l<eo va bj nen xuat hien trong ta'm be tong.
Do phan bd nhiet dp trong ta'm BT ludn la dudng cong, nen trong tam BT ludn xuat hien cac mien bi keo va nen. Mdt sd trong cac ke't qua tfnh toan duac the hien tren dd thj, hinh 811. Cd the rut ra cac nhan xet:
1. Nai phan each giu'a hai mien bj keo va bi nen la vi tri cd AT=0. Vi trf nay thay ddi lien tuc, nghTa la mien bi keo va nen trong ta'm BT trong ngay bie'n ddi lien tuc va luan phien nhau.
2. TCr 7h sang den 13h chieu, Idp mat tren day 5cm tam BT bj nen do nhan nhiet rat manh tCr mdi trudng (T<0). Ldp ke tiep day 15-20cm bj keo do AT>0 , Idp dudi cung day bj nen.
3. TCf 13h chieu, phan tren tam BT bj keo do td'c dp nhan nhiet giam. Sau 16h mien bj keo thu hep lai cdn khoang 5cm tai mat tren cho den 4h sang, sau dd chuyen sang bj nen. Cac Idp ke tie'p bj nen tCrsau 18h de'n 6h sang hdm sau.
d. Bien dang nhiet cue bg trong ta'm be tong Bie'n dang nhiet cue bp (BDCB) tai cac vj trf trong ta'm BT theo thdi gian trong ngay, vdi p-p = 10'
^ [4], dupc the hien tren cac hinh 12-^15. Bien dang keo tdi han E^th P^M thudc vao nhieu yeu td va loai be tdng, d day lay gia djnh theo [4], BT mac 200 cd Exth = 2,4.10'^. TCr cac dd thi cd the rut ra cac nhan xet sau :
1. Cac Idp trong tam BT ludn bi keo, nen luan phien nhau va thay ddi lien tuc trong mdt ngay dem, cd the gay nen hien tupng mdi nhiet.
2. Bien dang nhiet cue bd do bj keo Idn nhat tai be mat EJ = 0,5467.10" vao luc 18h nhd han bie'n dang keo tdi han, hinh 14, nen khdng gay ran nut pha huy, nhung do bj keo, nen luan phien gay mdi nhiet, lau dan be mat rat de bi ran nut.
Vung keo nen trong tam be tong luc IQti 55
60 O 45
^ Nen
Keo ^^""^"^^^^^^ii^^
Nen ^ s
60 p 55 SO
r
^45
•35 30 25 -
6 8 VI trj cac diem
Hinh 8. Luc 10h
Vung keo nen trong tam be tong luc 12h
6 S V) tri cac diem
Hinh 9. Luc 12 h trua
Vung keo nen Irong tam ba tong luc 16h I Keo
Nen "•/^"'^^•"-^
Hinhl0. Luc 16 gi&
Vung keo nen trong tam be tong luc 20h
S 10 12
Hinh11.Lue20h
TAP CHi CAU DUONG VIET NAM
K l o ' Bien dang nhiet trong tam be long luc 6h
Hinhl2. BDCB lue 6h
j( 10^ Bien dang nhiet trong lam be long luc lOh
Hinhl3. BDCB luelOh
X 10'^ Bien dang nhiet trong tam be long luc 18h
IV. KET LUAN
Viec khao sat trang thai nhiet tam BT bang pp PTHH, cho phep rut ra ke't luan sau:
- Vdi cung budc thdi gian, kfch thudc hinh hpc phan tCr cua cung mdt bai toan [2], khao sat bang pp PTHH cho cac ket qua chfnh xac nhu pp SPHH, cac nhan djnh hoan toan phu hpp nhau .
- PP PTHH cd uu diem khdng phai tinh the tfch, dien tfch phan td nhu pp SPHH.
- PP PTHH ed the ap dung cho cac vat the cd hinh dang bat quy tac nen kha nang tfnh toan md rdng han so vdi pp SPHH •
HinhU.BDCB iuelSh
TAI LIEU THAM KHAO
[1] Tran Oinh BiJu, Nguyen Quang Chieu. Khai thac va su'a chOa dudng d td, NXB DH-THCN 1984
[2] Trjnh Van Quang. Ket qua tfnh toan trang thai nhiet cua tam betdng dudi tac ddng cua dieu kien khf hau thay ddi. Tap chf Cau Dudng Viet nam. S d i 1,12, 2001.
[3] C.A.opMfl.TeMnepaxypHbie Hanpfl)KeHMn B 6eT0HHbix n
>Ke/ie3o6eTOHHbix KOHCTpyKumix rMApOTeXHMHeCKMX coopy>KeHMM rocyflapcTBHHoe. BHepreTunecKoe M3flTe/lbCTBO. MOCKBa 1959.
X 1 o'^ Bien dang nhiet trong lam be long luc 22h
[4] Le Van Cung. Khdng che nhiet dp dap be tdng Thac ba. Bao cao Hdi nghj KHXD 1985
[5] RW Lewis, P.Nithiharasu and Seetharamu.
Fundametals of The Finite Element Method for heat and fluid flow. John Wiley & Sons, Ltd. 2004.
Hinhl5. BDCB luc 22h
TAP CHi CAU OUdNG VIET NAM
PHiraNG PHAP TiNH HUONG XUNG DOT TRONG OANH GIA AN TOAN GIAO THONG TREN OU'ONG OTO
GS. TSKH. SILIANOV V.V.
Tru&ng DH Giao thong Dudng bd Moscow TS. DAO HUY HOANG
Vien Khoa hgc va Cdng nghe GTVT
I. Abstract: Evaluation of road traffic safety measures plays an important role in operationing and designing road. Basing on the evaluation results, we can propose solutions for improving traffic safety in operationing and designing road. The more accurate the method of evaluation as welt as result of this method brings, the more effective the solution result increases. Thus, researching on methods of evalua- tion method of traffic safety and its application in the situation of the country, regions, routine and traffic cor- ridor has an important meaning and needs to be researched in the current traffic situations of Vietnam.
Tom tat: Danh gia an toan chuyen dgng tren du&ng dtd dong mgt vai trd rat quan trgng trong khai thac cung nhu thiet ke du&ng dtd. Tren ca s& cac ket qua danh gia, ngu&i ta m&i cd the de xuat cac giai phap nang eao an toan chuyen dgng trong khai thac va thie't ke du&ng. Phuang phap si} dung dedanh gia cung nhu ket qua ma cac phuang phap nay dua ra cang chinh xac bao nhieu thi hieu qua cua cac giai phap se tang len bay nhieu. Chi'nh vi vay viec nghien ciiu cac phuang phap danh gia an loan chuyen ddng va viec ap dung no trong dieu kien dat nudc, viing mien, tuyen du&ng, hanh lang van til co mgt y nghTa rat quan trgng can duac nghien ciru trong dieu kien giao thdng dac thii & Viet nam hien nay.
I. TONG QUAN.
Trudc tinh hinh mat an toan giao thdng d i i n ra tren toan cau vdi mCrc dp ngay cang nghiem trpng, nhieu nha khoa hpc trong ITnh vuc An toan giao thdng(ATGT) tren the gidi da tien hanh nghien cCfu va de xuat cac phuang phap nham nang cao ATGT ngay cang hoan thien han. Tren ca sd phan tfch cac han che trong cac phuang phap thdng ke, xac xuat, phan tfch che dp chuyen ddng cua phuang tien giao thdng tren cac doan danh gia, ngudi ta da chi ra sucan thiet phai soan thao cac phuang phap mdi cho phep tfnh toan mdt each chi tiet han tat ca cac tinh hudng cd the xuat hien khi cac ddng giao thdng chuyen dpng tren dudng dtd va dudng phd. Vdi muc tieu khac phuc cac khd khan nay, phdng thf nghiem khoa hpc hang
"General Motors" d Detroit vao nam 1967 lan dau tien da de xuat phuang phap tinh huo'ng xung dot de danh gia mCrc dp an toan chuyen ddng tren dudng.
Ban d§u, phuang phap nay dupc ap dung de danh gia mCfc dp an toan chuyen ddng tren cac giao cit, tuy nhien sau dd phuang phap nay duac cai tien va phu
hpp ddi vdi ca cac doan dudng dtd khac do vay ngay cang dupc nhieu nudc tren the gidi su" dung.
Trong khudn khd bai viet nay se trlnh bay phuang phap tinh hudng xung dot, dupe sur dung trong danh gia md'c dp an toan giao thdng tren dudng dtd.
II. Npi DUNG.
Oa sd cac phuang phap danh gia miJc dp an toan giao thdng tren dudng dtd deu nam trong he phuang phap phan tfch thd'ng ke cac thdng tin ve tai nan giao thdng(TNGT). Khi tiep can theo hudng nay, ngudi ta chl ra dupe cac vj trf cd the nguy hiem thdng qua ket qua phan tich nguyen nhan dan den TNGT. Oe dua ra cac bien phap cd tfnh thuc thi va hieu qua cao trong cdng tac nang cao an toan giao thdng thl dieu quan trpng la khdng chi biet thdng ke TNGT ma can phai biet phan tfch nguyen nhan xuat hien chung.
Trong dd, ngudi ta can phan tfch cac ldi cu the cua nhung ngudi tham gia giao thdng va tim ra nhung ly do da dan den TNGT.
TAP CHI CAU OUdNG VIET NAM
