ASSESSMENT SCORING SYSTEM OF ROAD SAFETY INFRASTRUCTURE Case Study of Mihag District i Shaghai, Chia Yue Wag, Daocheg Su 2 School of Traffic ad Trasportatio Egieerig, Togi Uiversity, Shaghai, Chia ABSTRACT 2 Chia Academy of Urba Plaig & Desig, Beiig, Chia This paper presets a district-level study o assessmet of existig facilities o basis of which road safety ifrastructure plaig is established. Cosiderig locatio, history, populatio, ladscape, lad use, social ad ecoomy developmet, ad especially existig road etwork of Mihag district i Shaghai, this assessmet study was carried out with sample road sectios ad itersectios. The idicators icluded completio rate of traffic markigs ad sigs, istalmet ratioality of traffic sigs ad traffic sigals, pedestria crossig facilities, traffic cotrol of pedestria crosswalk ad itersectios, chaelizatio at itersectios ad separatios. Other elemets such as guardrails, sight-guidig facilities ad ati-glare equipmet were also cosidered. Road safety level was decided o the geeral score obtaied from two scorig systems. Oe was a two-stage evaluatio model of safety ifrastructure, ad the other put each idicator i two perspectives, completeess ad ratioality. Whe the fial score of situatio came out to be 73.96 ad 67.55 respectively, which could oly be categorized to medium level, black spots ad weak poits of road safety ifrastructure were excavated ad specific coutermeasures were discussed for diversified road sectios ad itersectios so as to prevet crashes ad improve local road safety. INTRODUCTION For recet decades, i circumstaces of rapid developmet of ecoomy, society ad costructio, trasportatio i Chia has become a popular issue whe this aciet coutry stepped ito a phase which cofrots icreasigly more crashes, especially crashes of high severity. Besides good etwork plaig ad structure desig, complete sets of road safety ifrastructure play a importat role i reducig quatity ad severity of crashes. It was ecessary to look ito the umber, positio ad patter of existig road safety ifrastructures ad their coordiatio with other compoets of road trasportatio system before reovatio plaig. Mihag district is located i the southwest dowtow area of Shaghai. This 37.68km 2 district was officially fouded i 992 ad gradually became a developig part of city which embodied suburba, urba ad rural fuctios. Whe this research was carried out Mihag had 830 thousad registered residets but the populatio was predicted to reach 2 millio till 2020 accordig regioal populatio report. There were 48 urba roads i Mihag, with the total legth of 430.64km. I the checkerboard-like road etwork, basic fuctio of road etwork structure was clear: expressways ad through roads established the framework, ad distributor roads lead access roads to make multi-coectios.
Figure. Geeral Plaig of Mihag district i Shaghai (Source: Shaghai Urba Plaig ad Desig Research Istitute) The 00km 2 plaig area cosisted two square parts, the upper part was surrouded by Huqigpig Hwy. (N), Middel Rig Rd. (E), Huhag Railway (W), Duaxig Rd. (S) i four directios, ad the lower oe was surrouded by Jiachua Rd. (N), Hogmei South Rd. (E), Kuyag Rd. (W), Huagpu River(S) i four directios. This mai priciples of this ifrastructure assessmet were beig scietific, obective, reliable ad practical. The obectives for this assessmet ad followig road safety ifrastructure plaig were to provide scietific assessmet method(s) for road safety ifrastructure scorig system; to realize crash reductio by elimiatig those crashes resulted from absece, poor quality or lack of itegrity of road safety ifrastructures; to improve road safety withi the plaig area through makig better ad more systematic desig for safety facilities; to proposig operative local policy to improve road safety maagemet, with the ultimate goal of promotig sustaiable developmet. As to the geeral status of existig road safety ifrastructure, accordig to documets provided by Shaghai traffic & trasportatio police departmet, there were 6040 traffic sigs i this district, cosistig of 468 guidig sigs, 006 warig sigs, 280 forbiddig sigs, 26 directioal sigs ad 25 auxiliary sigs. I the plaig area, traffic markigs had fair completio but wear out due to lack of fair maiteace; for road sectios with relatively high traffic volume separatio were marked or istalled, for road itersectios with relatively high traffic volume sigal cotrol facilities were istalled with appropriate sigal phase, itersectio chaelizatio rate was 75% while sight-guidig ad ati-glare facilities were ot adequately equipped. 2
METHOD Sample ivestigatio O accout of workload limit, samples were selected ad ivestigated upo 85% cofidece to represet geeral characteristics value. I this case, it would be reasoable to spread the ifrastructure sample plaig to the geeral plaig. The road sectio sample cosisted all though roads ad part of distributor/access roads, while the itersectio sample cosisted all though-road-ivolved itersectios ad part of distributor-distributor, distributor-access, access-access roads. Table. Desig Stadards for Urba Roads of Chia Desig Speed km/h Laes Red Lie Width Boudary m Express Roads 60 80 6 8 60 00 Through Roads 50 60 6 8 40 60 Distributor Roads 40 50 4 6 32 60 Access Roads 20 30 4 mixed 20 30 Table 2. Road Sectio Sample Through Roads Distributor Roads Access Roads Huqigpig Hwy, Jiachua Rd.; Caobao Rd.;Qixig Rd.; Yidu Rd. Hogmei Rd.; Hogmei South Rd.; Xisog Rd.; Dogchua Rd.; Humi Rd.; Dushi Rd.; Liahua South Rd. Jipig Rd.; Chuzhog Rd.; Shea Rd.; Table 3. Correspodig Itersectio Desig Express Roads Through Roads Distributor Roads Access Roads Express Roads A B A,B - Through Roads - A,B B,C B,D Distributor Roads - - C,D C,D Access Roads - - - D,E A Grade Separatio B Wideed Sigalized Itersectio C Roudabouts D Sigalized Itersectio E Usigalized Itersectio Table 4. Itersectio Sample N total 3 N ivestigated Through Roads ivolved 84 84 Distributor -Distributor 45 20 Distributor-Access 235 45 Access-Access 338 40
Sample verificatio It would be ecessary to statistically prove that sample characteristics could represet geeral characteristics. I this part, sample verificatio process of Distributor-Access itersectios is take as a example to demostrate. There were i total 235 Distributor-Access itersectios i the plaig area, a sample of 45 was obtaied with method of samplig without replacemet. I the verificatio, completeess of guidig sigs was chose as the basic idicator. If it is soud, it scores, while usoud scores 0. As a result, 32 i the sample were soud itersectios. Sice score result obeys 0- distributio B (, p), large sample method is applied to the calculatio as follows: x = 32/45 0.7 Radom variable is: X p J = X( X) Therefore, bilateral (approximately) limit of p with -α cofidece is: Let the mea error be 0., X( X) X ± µ α 2 x( x) µ α 2 = 0. µ α = x ( x ) 2 0. Whe α=0.5, x = 0.7, it is obtaied that =42.7 ad be geerated to be 43. That is to say, at the cofidece level of 85% characteristics of a sample of 43 Distributor-Access itersectios could represet geeral characteristics. Other samples of this research were verified i the same way. Idicators ad their meaigs For this road safety ifrastructure evaluatio, the followig 8 idicators are chose: Table 5. Idicators ad their meaigs 2 Sig Istalmet Sig Ratioality Markig Istalmet Separatio Facilities The proportio of istalled guidig sigs at itersectios to the umber of sigs that are ecessarily istalled. The clarity, ecessity, itegrity ad legibility of iformatio, whether it is coheret with road coditio ad eviromet. The proportio of paved road sectios wider tha 6m with markigs i total miles. Sidewalk is ot icluded The mile percetage of through roads with separatio facilities (cetral separatio ad separatio betwee 4
Safety Ifrastructure for Pedestrias Sigal Cotrol at Pedestria Crossigs Chaelizatio at Itersectios Sigal Cotrol Itersectios motorize ad o-motorized laes) i through roads of desig speed over 50km/ h ad more tha 4 laes The average distace betwee safety ifrastructure for pedestria (eg. crosswalks, pedestria overpasses ad uderpasses). The ratio of sigal cotrolled pedestria crosswalks to the umber of pedestria crosswalks that ought to be sigalized The proportio of chaelized itersectios i itersectios where roads wider tha 6m are ivolved. The ratio of sigal cotrolled itersectios to the umber of itersectios that eed to be sigalized Specifically, the secod idicator, the ratioality of traffic sig istallmet was geerated from site score, which was obtaied through addig results from five sub-idicators together the multiplied by 4. For each sub-idicator, there are five levels: highly qualified, very good, good, ok, uqualified, respectively. 5, 4, 3, 2, 0. These sub-idicators are: ecessity ad accordace with atioal ad regioal orms; positio (eg. reasoable agle ad height) ad quality; overall layout ad legibility; effectiveess of iformatio ad coherece; coordiatio with traffic flow, sigal cotrol ad itersectio chaelizatio. Table 6. Idicators ad their weight (AHP method) Idicators Weight Sig Istalmet 0.938 Sig Ratioality 0.3052 Markig Istalmet 0.938 Separatio Facilities 0.92 Safety Ifrastructure for Pedestrias 0.0336 Sigal Cotrol at Pedestria Crossigs 0.0494 Chaelizatio at Itersectios 0.0636 Sigal Cotrol Itersectios 0.044 Table 7. Idicators ad their score-value system Sig Istalmet Sig Ratioality Value [90,00) [80,90) [70,80) [60,70) [0,60) Score [90,00) [80,90) [70,80) [60,70) [0,60) Value [90,00] [80,90) [70,80) [60,70) [0,75) Score [90,00) [80,90) [70,80) [60,70) [0,60) Markig Value [90,00] [85,90) [80,85) [75,80) [0,75) Istalmet Score [90,00) [80,90) [70,80) [60,70) [0,60) Separatio Value [90,00) [80,90) [50,80) [20,50) [0,20) Score [90,00) [80,90) [70,80) [60,70) [0,60) 5
Safety Ifrastructure for Pedestrias Sigal Cotrol at Pedestria Crossigs Value <300 [300,350) [350,400) [400,450) >450 Score [90,00) [80,90) [70,80) [60,70) [0,60) Value [40,00) [30,40) [20,30) [0,20) [0,0) Score [90,00) [80,90) [70,80) [60,70) [0,60) Chaelizatio at Value [90,00] [85,90) [80,85) [75,80) [0,75) Itersectios Score [90,00) [80,90) [70,80) [60,70) [0,60) Sigal Cotrol Value [75,00] [65,75) [55,65) [45,55) [0,45) Itersectios Score [90,00) [80,90) [70,80) [60,70) [0,60) Method I Two methods were established to measure the road safety ifrastructure plaig. For the more complicated oe, geeral score was obtaied from two-stage evaluatio model of safety ifrastructure: Let factor set be U={u,u 2,u 3 }, i which factor set for traffic sigs ad markigs is u ={u,u 2,u 3,u 4 };factor set for sigal cotrol is u 2 ={u 2,u 22 } ad factor set for other road safety ifrastructure is u 3 ={u 3,u 32 }. Let evaluatio set be V={v,v 2,v 3 }, i which v meas highly qualified, v 2 meas qualified, v 3 meas ot qualified. Therefore, R r r2 r3 r r r M M M r r2 r3 2 22 23 = is obtaied as fuzzy udge matrix from U to V, whose elemet shows the evaluatio of factor set s membership degree to evaluatio set. Table 8. Idicators, scores ad weights Idicators Sub-idicators Score Weight Traffic sigs ad markigs Sigal cotrol Other road safety ifrastructure Markig completio 65.6 0.938 Sig istallmet 67.62 0.938 Sig Ratioality 67.86 0.3052 Chaelizatio at Itersectios Sigal Cotrol at Pedestria Crossigs Sigal Cotrol Itersectios Safety Ifrastructure for Pedestrias 76.67 0.0636 76.09 0.0494 92.42 0.044 98.65 0.0336 Separatio Facilities 98 0.92 0.7564 0.0908 0.528 6
The idicator traffic sigs ad markigs was take as a example to show how the evaluatio model work. 0 0.28 0.72 0 0.38 0.62 R = 0 0.39 0.6 0 0.83 0.7 For membership fuctios, if V ad V + are adacet gradig stadards, ad V> V +, the membership fuctio for V is: the membership fuctio for V is: r( x) r( x) The weight set A ( a a a ) x V + + = V V+ 0 < +, > x V V x V x V x V V x V + = V+ V 0 < +, > x V x V =, 2, L,, i which a i is the weight of the i-th factor, therefore, ai =. i= A=[0.938 0.938 0.3052 0.0636] With weighted average method, r r2 r3 r r r B = A R = a a a = M M M r r2 r3 Therefore, 0 0.28 0.72 0 0.38 0.62 B = A R = = 0 0.39 0.6 0 0.83 0.7 2 22 23 (, 2, L, ) ( b b2 b3 ) [ 0.938 0.938 0.3052 0.0636] [ 0 0.2997 0.4567] Let b*=b + b 2 + b 3 =0+0.2997+0.4567=0.7564, After ormalizatio, the result for idicator traffic sigs ad markigs could be obtaied: B* =[0 0.3962 0.6038] With the same method, for sigal cotrol, B* 2 =[0.283 0.609 0.08] For other road safety ifrastructure, B* 3 =[0.907 0.0929 0] 7
For the secod-stage evaluatio, * B Bm = A R = A M * B Makig assigmet V=[00,80,60], Sice A=[0.7564 0.0908 0.528], the fuzzy matrix for evaluated uit is the followig: Therefore, * * * T = 2 3 R B B B 0 0.3962 0.6038 B = A R = = 0.907 0.0929 0 [ 0.7564 0.0908 0.528] 0.283 0.609 0.08 [ 0.643 0.3692 0.4665] The the fial score for this method is obtaied: Method II 0.643 T D = VB = [ 00 80 60] 0.3692 = 73.96 0.4665 For the less complicated method, score is derived from two aspects - istallmet rate ad its ratioality (fit ability) - for each kid of road safety ifrastructure that is cosidered i this research. Table 9 shows the calculatio process. Table 9. Calculatio table Safety Ifrastructure Sigs Idicators ad sub-idicators Value Score Weight Istalmet rate 67.62% 67.62 0.938 60.87 ratioality 74.29 74.29 0.3052 Markigs 77.8% 65.60 0.938 Separatios Istalmet rate 98% Facilities Ratioality 80% Pedestrias Safety Istalmet 258.24m ifrastructure Ratioality 80% Sigalized pedestria crossig 26.09% 76.09 78.40 0.92 78.92 0.0336 77.24 0.0494 At Chaelizatio 83.33% 76.67 0.0636 82.88 Itersectios Sigal cotrol rate 8.05% 92.42 0.044 0.499 0.083 0.05 The fial score with this method came out to be 67.55 ad did ot eve reach the medium level. Results were ot optimistic. Therefore, i the ext step measures that aimed at improvemet were to be carried out. 8
DISCUSSION Though two ways were take i this study to lesse the ifluece of subective factor, ad multi-factor effects took their accout i the process of reachig the score, the methodology has a spatial room for improvemet. It is clear that the result is based o a relatively small sample of road sectios ad itersectios i oe particular district. The choice of idicators ad method trasferability eed to be discussed for other applicatios. A obvious deficiecy of this study is that huma factor was experimetally cosidered. If possible, it would be better to carry out further study o iteractio betwee road users especially drivers ad ifrastructure ad itegrate this aspect ito road safety ifrastructure evaluatio ad plaig i future cases. A further restrictio lies i the fact that big chages (both i traffic volume ad road fuctio) took place i Mihag district durig EXPO 200 site costructio ad regioal re-plaig after that, therefore, the before-after evaluatio of this road safety ifrastructure plaig could ot be carried out. ACKNOWLEGEMENT This study is a sub-proect of th Five-year Natioal Scietific Support Program, fuded by the Chiese Miistry of Sciece ad Techology. REFERENCES Avioam B, David S, Yisrael P, Sig locatio, sig recogitio, ad driver expectacies., Trasportatio Research Part F: Traffic Psychology ad Behaviour, Volume, November 2008, 459-465. Beoı t F, Impact of ifrastructure ad local eviromet o road usafety: Logistic modelig with spatial autocorrelatio. Accidet Aalysis & Prevetio, Volume 36, November 2004, 055 066. Daocheg S, Shou-e F, Research o assessmet of ifrastructure for urba road safety. Chia Muicipal Egieerig, Volume 3, Jue 2008, 3. Robert B N, Traffic fatalities ad iuries: the effect of chages i ifrastructure ad other treds., Accidet Aalysis & Prevetio, Volume 35, July 2003, 599 6. Robert B N, Lyoog O, The effect of ifrastructure ad demographic chage o traffic-related fatalities ad crashes: a case study of Illiois couty-level data, Accidet Aalysis & Prevetio, Volume 36, July 2004, 525 532. Upchurch J, Fisher D L, Carpeter C, Dutta A, Freeway guide sig desig with drivig simulator for Cetral Artery-Tuel, Bosto, Massachusetts., Trasportatio research record: Traffic cotrol devices, visibility ad rail-highway grade crossigs, 2002, 80, 9-7. Wedy A M, Errol R H, Drivers' awareess of traffic sig iformatio., Ergoomics, Volume 34, No.5, 99, 585-62. 9