Impacts of the Service Quality of single Road Facilities on the Service Quality in Networks

Transcription

1 Veröffentlchung / Publcaton Impacts of the Servce Qualty of sngle Road acltes on the Servce Qualty n Networks utoren / uthors: ernhard redrch Insttut für Verkehrswrtschaft, Straßenwesen und Städtebau, Unverstät Hannover fredrch@sh.un-hannover.de Markus redrch Lehrstuhl für Verkehrsplanung und Verkehrslettechnk, Unverstät Stuttgart markus.fredrch@sv.un-stuttgart.de hrstan Premer Insttut für Verkehrswrtschaft, Straßenwesen und Städtebau, Unverstät Hannover premer@vh.un-hannover.de Veröffentlcht n / Publshed n: redrch,., redrch, M., Premer,. (2006): Impacts of the Servce Qualty of sngle Road acltes on the Servce Qualty n Networks, Proceedngs of 5th Internatonal Symposum on Hghway apacty and Qualty of Servce, Yokohama Unverstät Stuttgart Insttut für Straßen- und Verkehrswesen Lehrstuhl für Verkehrsplanung und Verkehrslettechnk

2 IMPTS O THE SERVIE QULITY O SINGLE ROD ILITIES ON THE SERVIE QULITY IN NETWORKS ernhard redrch Professor, Unverstät Hannover, ppelstr. 9a, Hannover, Germany, phone , fax , fredrch@vh.un-hannover.de Markus redrch Professor, Unverstät Stuttgart, Sedenstr. 36, Stuttgart, Germany, , fax , markus.fredrch@sv.un-stuttgart.de hrstan Premer Research ssstant, Unverstät Hannover, ppelstr. 9a, Hannover, Germany, phone , fax , premer@vh.un-hannover.de STRT The paper examnes the relatonshp between the servce qualty of sngle road facltes and the servce qualty of entre journeys n road networks. It reports on a new approach to dentfy the level of servce (LOS c ) of entre journeys and compares the results wth the level of servce (LOS s ) determned for the sngle road facltes accordng to the German Hghway apacty Manual. The concept of a study s presented, where measured journey tmes and LOS c of selected od-pars are assocated wth LOS s measurements of the traversed road facltes. 1 INTRODUTION The German Hghway apacty Manual HS (Handbuch fuer de emessung von Strassenverkehrsanlagen, GSV 2001) lke other Hghway apacty Manuals provdes a collecton of methods for evaluatng the Level of Servce for sngle road facltes,.e. a partcular network element lke a road segment, a ramp, or an ntersecton. The Level of Servce of sngle road facltes (LOS s ) s derved from the volume capacty rato, the delay tme or the traffc densty. In addton to the HS the German gudelnes provde a complementary Gudelne for Integrated Network Plannng RIN (Rchtlnen für de ntegrerte Netzgestaltung, GSV 2005) whch s used for categorsng road networks and for evaluatng the servce qualty n mult-modal networks. Here the key ndcator for measurng the level of servce (LOS c ) of an entre journey s the drect speed,.e. the total journey tme from orgn to destnaton dvded by the drect dstance. The network servce qualty s determned for a set of relatons (od-pars) descrbed n a herarchy matrx whch contans all relevant relatons n the network. Ths herarchy matrx derves the mportance of a relaton based on the entral Place Theory (PT) proposed by hrstaller (1933) from the herarchy of settlements. Up to now the two gudelnes HS and RIN are only connected loosely. There s lttle knowledge how the Level of Servce of an entre relaton relates to the Level of Servce determned for the set of road facltes traversed by ths partcular relaton. poor Level of Servce of a sngle road faclty accordng to HS may not necessarly lead to a low Level of Servce for the relatons passng through ths faclty. Lnkng the servce qualty of relatons and sngle road facltes could supply nformaton about the requred Level of Servce for a specfc road faclty. current research project examnes to what extent the servce qualty of sngle road facltes nfluences the servce qualty of entre relatons and the entre network. To acheve ths the project

3 analyses a varety of relatons by comparng computed Level of Servce accordng to HS/RIN and observed servce qualty from journey tme measurements. or each examned relaton the analyss ncludes relevant alternatve routes whch may be used n case of dsturbances or for traffc control measures. The paper wll present the fundamental deas for measurng the servce qualty for networks as defned n the RIN gudelne and t wll report on results of the research project,.e. about the relatonshp between the servce qualty of sngle road facltes based on HS and the servce qualty n networks accordng to RIN. 2 EVLUTION O SERVIE QULITY IN ROD NETWORKS 2.1 Servce qualty of sngle road facltes The German Hghway apacty Manual HS, publshed n 2001, provdes a set of methods to determne the Level of Servce (rangng from to ) for sngle road facltes,.e. a partcular element n the network. The HS consders several types of road facltes, namely freeway segments, grade-separated ntersectons wth ramps, rural roads, sgnal controlled and yeld controlled ntersectons. The HS methods dentfy for each type of road faclty a specfc capacty and assgn the actual traffc volumes to specfc servce levels, whch promse defned qualtes of the traffc flow. The crtera appled for each type of road faclty are shown n table 1. Ths way t s possble to determne the LOS s of sngle road facltes. However, ts broad mpact on the entre road network s not taken nto account. Untl now, there exsts no method n the HS to estmate the mpacts of the servce qualty of a sngle road faclty (e.g. a congested ntersecton) on the servce qualty n the network (journey tme, drect speed). Lkewse the U.S. Hghway apacty Manual HM (Transportaton Research oard, 2000) does not nclude a method for determnng the LOS c of an entre journey, only for a sequence of road segments. It only permts to examne ntersectons, or road segments between ntersectons. composte complete assessment of all the sngle road elements traversed wthn the course of a journey s not possble. Table 1 Qualty crtera for sngle road facltes Type of Road aclty Qualty rteron freeway segment capacty rato grade-separated ntersecton capacty rato two lane rural road traffc densty sgnal controlled ntersecton delay tme yeld controlled ntersecton delay tme 2.2 Servce qualty n networks The RIN gudelne provdes a method for categorsng road networks and for evaluatng the servce qualty. Ths method comprses fve major steps: 1. Development of herarchy matrces: On the bass of the spatal unts of the study area (central places, mportant transfer locatons lke arports) herarchy matrces are developed for dfferent herarchy levels. Level 1 matrces for example contan long-dstance relatons whch connect metropoltan areas. Level 2 matrces enclose medum-dstance relatons between towns of medum mportance. The herarchy matrces contan all od-pars whch are of mportance for network plannng.

4 2. ssgnment of herarchy matrces: In order to determne the mportance of each network element the herarchy matrces are assgned to the network,.e. for each od-par defned n the herarchy matrces an approprate route s dentfed. Route assgnment consders not only tme but also other factors lke safety, and bundlng of transport flows. 3. ategorzng the network: The category of a network element results from the set of routes traversng the element. The route wth the hghest herarchy level determnes the category of the network element. 4. Determnng and evaluatng the servce qualty: or each od-par defned n the herarchy matrces the servce qualty s descrbed by a set of ndcators (journey tme, drect speed, drectness, etc). To evaluate the servce qualty the ndcator values are compared wth target values. Ths results n a LOS c value for examned od-par and each mode of transport (car, publc transport, park & rde). 5. Desgn of sngle network elements: The desred characterstcs of sngle network elements (streets, ramps, ntersectons) are derved from the category of the network element. The characterstcs nclude the type of ntersecton control, the type of road cross secton and the desgn speed. or network elements whch are used by a hgh number of od-par wth a poor servce qualty approprate desgn measures should be examned to ncrease the performance. Metropoltan rea Major Town gure 1: Level 1 herarchy matrx for Germany

5 The most mportant ndcator for evaluatng the servce qualty of a partcular od-par s the drect speed (= drect dstance / journey tme). Journey tme and the resultng drect speed nclude not only the n-vehcle tme but also access and egress tmes whch can reduce the speed of the entre journey sgnfcantly, especally n publc transport. It s of advantage to use the ndcator drect speed nstead of journey tme as t mplctly ncludes the dstance. s a journey always comprses low-speed sectons (access walk, feeder network) and sectons wth hgher speed (arteral roads, motorways) the dstance nevertheless nfluences the feasble speed. In short-dstance trps the mpact of the low-speed sectons s hgher than n long-dstance trps. gure 2 shows the LOS c for evaluatng the drect speed of relatons. gure 2: Level of Servce LOS c for evaluatng the drect speed of relatons Obvously the LOS c n road transport can vary dependng on the traffc condtons. The RIN gudelne suggests to determne the LOS c for the peak perod. Practcal applcatons of the evaluaton method, however, face the problem of how to quantfy the peak perod journey tme of entre relatons. Three fundamental approaches can be consdered: Measurng the journey tme: The journey tme s measured drectly by a car drve. Ths approach provdes realstc values, f the measurements are repeated over a longer tme perod, to make sure that random dsturbances (e.g. accdents) do not sgnfcantly nfluence the result. The approach, however, s too expensve for examnng all od-pars of a network and can not be used for the evaluaton of future network states. Observng the journey tme: The journey tme s derved from observatons of journeys by means of floatng car data (D) or floatng phone data from moble phones. Ths approach would provde an deal data set for contnuously montorng the servce qualty n the network. Unfortunately at present such data are rarely avalable. Modellng the journey tme: The journey tme s computed by a macro- or mcroscopc traffc flow model. In prncple ths approach s sutable for large networks and for examnng future states. The man dffculty of the approach results from the fact that such a model requres relable nformaton on traffc volumes and route choce. Up to now applcatons of the evaluaton method used tradtonal peak hour assgnment methods whch n some cases were calbrated by measurements of the journey tme for selected od-pars.

6 3 DT OLLETION ND PROESSING To examne the mpact of the servce qualty of sngle road facltes on the qualty of network relatons both the LOS s of all facltes traversed by the relaton and the overall journey tme of ths relaton need to be analysed. s the servce qualty vares wthn the course of a day the analyss must nclude journeys wth dfferent departure tmes and consder the correspondng traffc volumes on the road. The research project examnes 10 relatons each lnkng a dstnct par of ctes wth partcular regonal functons (.e. ctes wth major, medum and mnor regonal relevance). Each relaton s connected through a mnmum of two alternatve routes. or every relaton the set of relevant routes s decomposed nto sngle segments whch are subjects of a LOS s analyss accordng to the HS methodology. gure 3: Measurement concept The requred traffc data are surveyed usng dfferent measurements n order to provde maxmum nformaton on traffc flow condtons over space and tme. The followng measurements are performed durng three hour perods of mornng and afternoon peaks: Two floatng cars equpped wth GPS devces travel contnuously on the routes of the od-par. The vehcle postons are recorded every second. Ths provdes tme-dependent tme-space trajectores along the routes for dscrete departure tmes (mcroscopc perspectve). Infrared cameras of an automatc number plate recognton (NPR) system are postoned at partcular locatons n the network n order to collect data sets on journey tme and travel speed on the dfferent routes for a large number of travellers (macroscopc perspectve). Traffc volumes are counted at all locatons requred for determnng the LOS s of sngle road facltes accordng to HS. or ths purpose data from permanent and moble detectors are used. Snce t has to be consdered that the data collected may not cover the entre range of traffc demand partcularly for hgh demand stuatons, the emprc data s completed by smulated data from a mcroscopc traffc flow smulaton.

7 gure 4 shows the tme-space trajectores of one route. The journey tme vares dependng on the departure tme. Ths results n a tme dependent LOS c for the entre journey whch s also shown n gure 4. gure 5 dsplays the correspondng tme measurements of all vehcles detected by the NPR system between two locatons. The measured travel tmes do not drectly refer to the journey tmes n gure 4 as they cover only the part of the journey between the two measurement locatons. They prove, however, that the tme-space trajectores represent a vehcle wth average travel tmes NPR 1 NPR 2 LOS E tme [s] LOS D LOS LOS start 07:05 start 07:25 start 07:50 start 08:15 start 08:50 start 16:10 start 16:40 start 16:45 start 17:45 start 18: dstance [m] gure 4: Tme-space trajectores of one route (Selgenstadt - rankfurt a.m) for dfferent departure tmes wth LOS c value for the entre journey travel tme [s] :00 5:30 6:00 6:30 7:00 7:30 8:00 8:30 9:00 9:30 10:00 tme of day [-] gure 5: Travel tme measurements from NPR systems

8 The LOS s of each sngle road faclty along the route s calculated accordng to HS based on traffc volume, traffc densty, and delay tmes. The LOS s of each road faclty also vares wthn the course of a day. gure 6 shows the tme-dependent LOS s of sngle road facltes. 09:45 09:30 09:15 urban area motorway urban area LOS c D 09:00 08:45 E LOS c E tme of day [-] 08:30 08:15 08:00 07:45 07:30 07:15 E E D E E LOS c D LOS c LOS c 07: dstance [m] gure 6: Tme-space trajectores and tme-dependent LOS s of sngle road facltes of one route (Selgenstadt rankfurt a. M. ) n the mornng peak perod 4 IMPTS O SINGLE ROD ILITIES ON OMPLETE JOURNEYS The data descrbed above form the bass for analysng the relatonshp between the LOS s of sngle road facltes and the LOS c for complete journeys. Dfferent modellng approaches are consdered: omparson of LOS c of a journey aganst the weghted mean LOS w, whch s calculated from the sngle LOS s of the traversed road facltes weghted by ther length. nalogous calculaton of a weghted mean LOS w usng not the length but the tme as a weghtng factor. nalogous calculaton of a weghted mean LOS w usng not dscrete but contnuous LOS s values. Harmoncally standardzed capacty rato LOS m omparson of total delay tmes of a journey wth the sum of calculated delay tmes at sngle road facltes. Up to now only the frst model,.e. the weghted LOS w, was analysed usng the emprc data. The dea of weghng the LOS s of sngle facltes and to merge them to one characterstc value, whch represents the LOS c of the complete journey, requres a transformaton of the semantc levels (LOS s LOS s ) to dscrete nteger values from 1 to 6. The length of each road facltes s used as a weghtng factor. ccordngly the LOS w can be formulated as follows:

9 LOS w = n 1 l = 1 n = 1 NV l = 1 L n compl = 1 NV l wth: l NV L compl n secton length of the secton numercal value of the LOS of the traversed road faclty at secton total length of route number of sectons pplyng ths smple model wth real data results n a reasonable correlaton of both LOS-ndcators as can be seen from gure 7. Ths fgure shows the measured drect speed and the calculated LOS w of four routes for varous departure tmes. s expected the drect speed falls wth ncreasng LOS w. Examnng a partcular journey of 20 km drect dstance (route Selgenstadt rankfurt) a clear lnear relatonshp (R²=0,91) between LOS w and the LOS c accordng to RIN can be stated (gure 8). 70 LOS w LOS w LOS w LOS w D LOS w E LOS w drect speed [km/h] ,5 1,5 2,5 3,5 4,5 5,5 weghted mean LOSw [-] Darmstadt-Groß Gerau Selgenstadt-rankfurt Husum-Hede Darmstadt-Mannhem_5 gure 7: omparson of LOS w and drect speed Supposed that these frst results can be proved by further valdaton, ths model allows for the analyss of the mpacts of overloaded sngle facltes on the whole journey. onsequently the effcency of alternatve local measures to mprove the overall LOS c can be assessed by ths method. s an example for such an mpact analyss a secton of the motorway Selgenstadt rankfurt (gure 6, segment 6-9 between km and km ) s consdered, whch s frequently congested. Ths secton covers two grade-separated nterchanges wth on- and off-ramps (segment 6 an 8) and two basc freeway segments (segment 7 an 9). or the start tme 8:50 both LOS c and LOS w show a value of D (drect speed = 28 km/h, LOS w = 4,4). The lnear functonal relaton derved above now could be used to estmate the mpacts and, f costs were avalable, the

10 effcency of alternatve local measures whch could be mplemented n order to mprove the servce qualty of the complete journey. In ths context four alternatves are consdered: lternatve : Enhancement of the capacty of all segments 6-9 to mprove LOS s of all four segments from to D. lternatve : Enhancement of the capacty of the freeway segments (segments 7, 9) to mprove LOS s from to D. lternatve : Enhancement of the capacty of all segments 6-9 mprove LOS s of all four segments from to E. lternatve D: Enhancement of the capacty of the nterchanges (segments 6, 8) to mprove LOS s from to D. 70 LOS w LOS w LOS w LOS w D LOS w E LOS w y = -9,1337x + 66,005 R 2 = 0,9075 LOS c drect speed [km/h] D LOS c LOS c LOS c D LOS c E LOS c 0 0,5 1,5 2,5 3,5 4,5 5,5 weghted mean of the LOS w [-] gure 8: Impact analyss The mpact analyss shows that the hghest beneft could be acheved by alternatve, whch s the most expensve one. Drect speed would be ncreased by some 9,3 km/h and would provde a LOS c of accordng to RIN (gure 8). lternatve whch mproves the LOS s to LOS s E for all four segments, however, s less effectve (+ 4,6 km/h) than alternatve whch only mproves the LOS s of the freeway segments from to D (+6,4 km/h,). The presented fndngs result from a frst data analyss of 4 out of the 10 examned relatons. The assumed coherences wll be verfed and modfed n the progressve work. 5 ONLUSION The presented study ams at dentfyng the mpact of sngle road facltes on the network,.e. the mpact on all journeys traversng that partcular road faclty. Such an analyss can help to locate sngle road facltes n a network where mprovements are most benefcal and thus to rank nfrastructure nvestments. If a sngle road faclty wth a low LOS s durng peak hour was only utlsed by journeys wth a decent LOS c concernng the drect speed mprovements are desrable but not urgent. However, f ths sngle road faclty was traversed by several od-pars wth a poor LOS c,

11 an extenson of the partcular road faclty or modfcatons n the network should be examned. The presented project s a plot study to examne the benefts of a plannng process whch ntegrates network plannng and desgn of road facltes. The analyss of the feld survey data s stll under examnaton, but the frst results show, that the methods can help to dentfy road facltes wth a low servce qualty whch at the same tme have a hgh nfluence on the qualty of entre relatons. s mentoned above a major drawback of such a method are the substantal requrements concernng the measurements of journey tmes for varous od-pars and tme ntervals. The requred technology (lcence plate detecton, floatng car data, floatng phone data from moble phones) are not yet avalable on a large scale or are stll a pont of research. Wth more and contnuous data on journey tmes t would be nterestng to examne, f the drect speed of an od-par leadng to a LOS c value can be defned n a smlar way as for sngle road facltes n the HS. Here the desgn volumes for determnng the LOS s are defned by the traffc volume whch s observed for the 30 th busest hour wthn a year. REERENES GSV, orschungsgesellschaft für Strassen- und Verkehrswesen (2001). Handbuch für de emessung von Straßenverkehrsanlagen HS (German Hghway apacty Manual), GSV, orschungsgesellschaft für Strassen- und Verkehrswesen (2005). Rchtlnen fuer de ntegrerte Netzgestaltung RIN (German Gudelne for Integrated Network Plannng), Draft. hrstaller, W. (1933). De zentralen Orte n Süddeutschland. Gustav scher, Jena. - Translated n part by askn.w. (1966). entral Places n Southern Germany. Prentce Hall. Transportaton Research oard (2000). Hghway apacty Manual HM, Washngton, D..