Changing Pattern of Urban Travel and Implications for Land Use and Transport Strategy

Transcription

1 TRANSPORTATON RESEARCH RECORD Changing Pattern of Urban Travel and mpliations for Land Use and Transport Strategy F. v. WEBSTER AND P. H. BLY The Transport and Road Researh Laboratory arried out a study of the hanging patterns of urban travel for the European Conferene of Ministers of Transport. This study eamined the various fators that affet the use of publi and private transport in ities and onluded that publi transport would ultimately deline even in those ountries where its use was urrently rising. n ontrast the fators that favor ar use were likely to ontinue to do so well into the future. n this paper the impliations of those findings and some of the options available to poliy makers are eamined. Publi transport use has been delining for more than 3 years in the United Kingdom, and urrent land use trends are making it inreasingly diffiult to provide adequate publi transport servies in areas where jobs, homes, and other failities are beoming more and more dispersed. There is onern for those who do not have aess to a private ar and who are dependent on publi transport. There is also onern in many quarters for the urban areas themselves-the inreasing urban sprawl, the spread of ongestion in both time and spae, and the areas of derelition that are appearing in some of the inner suburbs. Many planners onerned with these problems view with envious eyes some of the more attrative Continental ities, whih have managed to remain reasonably ompat and to retain thriving enters bustling with life and ativity, and where use of publi transport is stable, or even inreasing. Even so, some poliy makers in these ountries are worried by the inreasing amounts of subsidy absorbed by publi transport and by soial and eonomi hanges that may adversely affet urban vitality in the future. The onern for the way ities are developing and the impliations of this for travel led the U.K. Transport and Road Researh Laboratory to embark on a study of urban travel in a number of different types of ities under the auspies of the European Conferene of Ministers of Transport (ECMT), whih greatly failitated the olletion of data from more than 1 ities in 16 ountries. The work was arried out by the present authors and M. Dasgupta, R. H. Johnston, and N. J. Paulley. The results of the study were presented to the Counil of Ministers in 1984 and the report was published by ECMT in 1985 (1). n this paper a rather qualitative summary is provided of the main findings of the ECMT study, and on this basis the impli- U.K. Transport and Road Researh Laboratory, Department of Transport, Old Wokingham Road, Crowthorne, Berkshire RG 6AU, England. ations for future urban poliy are set out. The trends in the main fators that affet the use of publi and private travel modes are eamined, and how these might hange in the future is onsidered. The options open to poliy makers are desribed, and the likely impats of adopting partiular poliies are assessed. PAST TRENDS The main trends affeting travel are those that are onerned with the ost of travel (and the ability to afford it), the quality of travel, the benefits of traveling to partiular plaes, and the relative loations of origins and destinations. nreasing Affluene The universal inrease in ar ownership is a diret result of inreasing affluene and there is no sign yet of approahing saturation, even in rih ountries like the United States (Figure 1). Having a ar available is the biggest single fator affeting use of publi transport, and a surprising similarity in the effet of ar ownership in different ities and ountries was found, as shown in Figure 2. A first ar in a household results in a drop in publi transport trip making of roughly 4 perent; the addition of a seond ar removes a further 3 perent of the remaining publi transport trips. nreasing affluene also allows travelers to shift from "heap" modes, like walking and yling, to more epensive ones, like ar and publi transport. Figure 3 shows how ar ownership affets trip making by different modes aross samples of households surveyed in both Britain and Frane. The ar takes the majority of trips in ar-owning households and is likely to be preferred for almost all journeys for whih it is both suitable and available, but more affluene will nevertheless generate some etra travel in the form of new trips or etensions to eisting ones. Figure 3 shows that ar ownership redues both walking and publi transport use overall, but, nevertheless, inreasing affluene may enourage some transfer of trips from walking to publi transport. This will tend to our when aess times are low (more people will "hop on a bus") and when there is some benefit from taking a longer bus trip to a more distant destination instead of a short walk to a loal destination. Journeys by yle or moped are similar in length to bus journeys so that inreasing affluene may well enourage some transfer, though, as Figure 3 shows, trip rates

2 22 TRANSPORTATON RESEARCH RECORD 1125!'l... u ('V' _; ,.-- / -,..J ( /..- USA // ' - ' l,... Canada Australia Private ar Publi Transport D Walk u u._ Motoryle EL] Pedal yle Greee.. 1 ' -,,/. g 1.5 a..9...: 1. O. --ll-...:::..:...i:...:...--l--l-l-l Year FGURE 1 Growth in ar ownership in a number of ountries (2)..5 by these modes in most British ities are fairly low. n many Continental ountries, however, the sope for transfer isgreater, though diminishing. The study showed that transfer from twowheeled trips to publi transport has been an important fator in a number of Frenh ities (3). Prie and Quality Car running osts have remained fairly steady in most ountries u.e o.6. 5 t'.4 g_ u <1>,2 :J a :.... & Britain.. e F rane Germany ' L-LJ_J_-'--'---1--L-' Trip rate : hou se holds with no ar FGURE 2 Comparison of trip rates for bus and tram of households with and without ars in a sample of British, Frenh, and German ities... FGURE 3 Daily trip rates in a sample of major towns in Britain and Frane for different levels of ar ownership. for many years despite two oil rises in the 197s. n ontrast, almost everywhere despite a general improvement in produtivity, but subsidies have ushioned these rises so that in some ountries, partiularly in Continental Europe, fares have atually fallen. n the United Kingdom, inreases in subsidy have not been suffiient to offset rises in osts and the effets of redued patronage, so fares have risen onsistently over the years relative to other pries, ausing appreiable redutions in publi transport use. Road network speeds have been relatively onstant over the years, though in the larger ities there has been some peak spreading. However, beause more and more journeys are made in the outer areas of ities as both population and employment disperse, travel by ar is generally beoming faster. n-vehile speeds of bus travel are probably inreasing for the same reason, but total journey speeds (inluding walking and waiting) are falling in many ities beause of the longer aess

3 Webster and Bly 23 z :;( > a: Q z <{ Greater London 75 o Ol T r- > Fator. d1--rril relative to retail 4 rlil u.;, oon 2 (per vehile-km) o u * prie -2 n,..., D n Produtivity oj:11..,. D :< dl= (vehile-km * -2 L...J. LJ L per employee) i kro ij rr-fl 2 er er.i= u u Q;. :l <{ -3-6 Fares (relative LJ to retail pries) 3 Servie ojj ;:. CJ:[h-r-, (vehile-km -3 LJ operated) 2 n,...-, n Passengers odhh 4 L - J-.."l (pmsenger trips _ 2 LP LJ LJ arried) -4 FGURE 4 Mean annual trends in publi transport osts, produtivity, fares, servie, and ridership between 197 and 198. times that result from the lower servie levels and sparser route networks in outer areas. n addition to this effet, waiting times on all routes (entral and outer) in British ities are tending to lengthen as servies are redued in response to falling patronage-a trend that is not relevant to Continental ities where patronage is buoyant (Figure 4). Movement of Population n almost all developed ountries there has been a drift of population from large ities to small towns over many years. Superimposed on this is the migration from rural areas to urban areas that is still ontinuing in some ountries, partiularly in southern Europe (urbanization eased about 3 years ago in Britain). The net result of these hanges is that many large Continental ities are still growing while the larger British ities and some of those in northeastern Europe are delining. Figure 5 shows how London peaked in the early 195s and the main onurbations in the 196s; medium-sized ities are approahing their peak at the present time, and smaller towns are still growing strongly. Publi transport in many of the larger Continental ities is gaining patronage from the etra population, but in the United Kingdom the delining population of the larger ities is responsible for some loss of patronage. These losses are not aneled out by orresponding inreases in patronage in the epanding smaller towns beause people in smaller towns have less need for publi transport... N v; E.'!! > <{ Over 25 1 to Year FGURE S Changes in population of towns of different sizes in England and Wales, 1931 to ' "1981 \ Munih.., ' --- u ' ' Lyon.i= 1 Q;,1968 \ \. ',, :\ Sl Q; 8,, ' \ '\\ \ '19a2,, \ T ;::;.!!? 4 (,981, \ :l. a. 2 Manhester , Distane from ity entre (km) FGURE 6 Changes in population density with distane from ity enter. n addition to these trends there is also a movement of population from inner to outer areas of pratially all major ities; this is ausing a general deline in built densities, espeially in the inner areas, as shown in Figure 6. Beause of

4 24 TRANSPORTATON RESEARCH RECORD 1125 the ompatness of many Continental ities, a relatively high proportion of the inhabitants live lose enough to workplaes, shops, and other failities to walk or yle to them. Population dispersion leads to a greater need for mehanized journeys, and although this enourages ar use, publi transport also gains, partiularly if ativities remain in the ity enter. Suburbanization in the United Kingdom in the first half of the entury led to trip rates by publi transport that were among the highest reorded anywhere in the world (they are still high despite many years of deline), but ar ownership levels were low at that time. Any enouragement that suburbanization might give to publi transport in the epanding ities of Europe will now be muh smaller than it was in the United Kingdom beause ar ownership levels are high. Even though initial spreading an bolster publi transport use, further dispersion will eventually result in suburban development that is more diffiuit to serve by pubii transport and more onvenient for the private ar, unless development takes the form of "beads on a string" (i.e., high-density settlements surrounded by "green" areas and onneted by fast, frequent publi transport systems, usually rail; Stokholm and Paris offer good eamples of these systems). Thus in some ities the dominant forms of suburbanization are produing a lustered type of settlement pattern that might atually inrease publi transport use in spite of the dispersion of population and delining overall densities. n others, densities have fallen more uniformly and to relatively low levels, produing the amorphous suburbanization that greatly weakens publi transport. Changes n Employment Many of the traditional manufaturing industries of the older ities are dying, leaving the inner ity areas surrounding the entral business distrits (CBDs) of suh towns with a diminishing number of employment opportunities. New industries, partiularly servie industries and high-tehnology manufaturing, are inreasingly likely to loate in smaller towns, as the data in Table 1 indiate, or in the outer areas of larger towns where land is heap and aess to the national road network is good. When both the origin and the destination of trips are in the outer areas, the provision of an adequate publi transport servie beomes even more diffiult and epensive than when only the population is dispersed, and the use of the ar is made easier. Servie and retail employment is still largely entrally based and growing, but growth in the outer areas is proportionately greater than in the enter, albeit from a smaller base. Although publi transport stands to gain from this growth in the ity enter, it is generally not suffiient to ounter the loss of trips aused by the redutions in the manufaturing industry in the area surrounding the CBD. On the whole, therefore, hanges in employment loation are tending to work against the use of publi transport and in favor of the ar, though the growth in servie employment in some towns (e.g., Toronto) is so great that publi transport use is still on the inrease. Modeling the Changes n the ECMT study () a mathematial model was used to predit the hanges in patronage that ould be epeted to result from the obsrv"d hanges from one year to the net in real fares (F), vehile-kilometers operated (K), number of ars registered nationally (C), national population (N), level of urbanization (U), and number of unemployed workers as a proportion of the population (J). The model form was where P,. f, and h are onstants and e 1 and ek are the elastiities of demand with respet to fares and vehile-kilometers. The values of these onstants were based on the results of statistial regression analysis of the data olleted, but in some ases the values obtained from regression were modified in the light of other available information. Beause no systemati pattern ould be diserned in the statistial relationships estimated for eah individual ountry (and, of ourse, some were not statistially signifiantly different from zero), the same values of the oeffiients were used for all ountries, eept that was varied with the level of ar ownership (1, Appendi). Moreover, the fare and servie elastiities (e 1 and e,j were given rather larger values than the short-term estimates to represent the longer-term impats of hanging fares and servie; this was in line with other TRRL work on prediting the use of publi transport (5). The effet of urbanization, in partiular, ould be handled only in a quite rude way beause of the lak of suitable data. The differene between the estimated hange and the atual hange, averaged over the period 197 to 198, is the TABLE 1 CHANGES N TYPE OF EMPLOYMENT N GREAT BRTAN BETWEEN 1959 AND 1975 (4) Change as Perentage of Total Employment in Eah Area in 1959 Agriulture Mining Manufaturing Servies Total London Conurbations Free-standing ities ndustrial towns County towns Rural areas Whole of Great Britain NoTE: n this table the hange in eah setor is epressed as a perentage of total employment in eah area in For instane. in London the fall in manufaturing employment between 1959 and 1975 was 13 perent of all employment in London in 1959, but as a proportion of all manufaturing employment in London it was 38 perent.

5 Webster and Bly "residual" trend: this is the uneplained part of the trend, representing the ombined effet of fators that have not been onsidered in the alulations or the treatment of whih is otherwise inadequate. The degree of eplanation ahieved is measured by the etent to whih the residual trend has a smaller spread of values aross the various ountries than had the observed trend. There is, of ourse, onsiderable unertainty in trying to aount for the observed trends in this way, but the model was subjeted to a range of sensitivity tests, and in general the relative residual trends for the different ountries, and the width of their spread, were fairly stable to hanges in the assumptions (1, Appendi). Figure 7 shows the ountries ranked aording to the magnitude of the residual trends and the ontribution of the individual fators to the eplanation of the trends between 197 and 198. The standard deviation of the residual trends is 1.39 and that for the atual trends is 2.3. Thus it appears that the model is able to eplain about one-third of the variation. n addition to these fators, however, those ountries with a high absolute level of use show a more positive trend over time, other things being equal, than those ountries with low use. When this aspet of the eplanation is taken into aount, it appears that more than one-half of the variation in patronage an be aounted for and perhaps three-quarters of that part of the variation that is likely to be epliable (bearing in mind the inherent variability of the data). The ranking of the ountries aording to their residual trends appears tolerably plausible: for eample, in taly, Sweden, Germany, and Switzerland the atual trends are appreiably more positive than the assumed model would suggest, possibly beause of heavier than normal use of rail, whih may be more effetive than bus servies in retaining patronage in the fae of ompetition from the ar. n taly the relatively fast growth of the larger ities, whih was not adequately refleted in the overall measure of urbanization, has probably been partly responsible for the positive trend. At the other end of the spetrum are Australia, New Zealand, and the United States, whih have favored an espeially low-density form of suburbanization, whih is partiularly unsuited to the use of publi transport. Thus the atual trend in these ountries is lower than the model would suggest. Nevertheless, it is reassuring that so muh of the variation in patronage trends an be eplained by a model that assumes that various fators work at the same strength in eah of the different types of ountries inluded. t was also of interest that the residual trends for Frane, Britain, Spain, and reland were lose to zero: in other words the patronage trend was almost ompletely eplained by the mehanisms inluded and at the strengths assumed. Thus, ompared with other ountries, there are no speial reasons that make provision of publi transport in these ountries either espeially diffiult or speially easy--hanges in use are due to fators that appear to be working in all of the ountries at muh the same strength. MPLCATONS FOR THE FUTURE Table 2 gives a summary of the various fators that influene use of publi transport or ar, and it ontrasts the situation in the United Kingdom, with its delining publi transport trend, with that in may of the ountries in Continental Europe. n the United Kingdom, all of the fators tend to work against publi transport and in favor of inreasing ar use, whereas in many Continental European ountries some of the fators still favor publi transport. However, they will not ontinue to do so indefinitely. Urbanization is lose to saturation, further redutions in density are likely to reate the sort of dispersed suburbanization that enourages ar use instead of publi transport, and even the reation of high-density satellite settlements will not ontinue to bolster ommuter rail if entral-area employment delines or if people elet to live or work in a more 25 Ridership Trend, % per year Contributions of omponent fators taly Sweden Germany (FRG Switzerland Canada Finland Belgium Frane Great Brita in Spain reland Norway USA New Zealand Austral ia Overall Average : +O 7 Standard Deviation: 2.3 Atual Trend Fares Servie Cars Popu- Urban- Unemp- Residual lat ion isation loyment Trend Overall Average : +.41 Standard Deviation: 1.39 taly Sweden Germany (FRG Switzerland Canada Finland Belgium Frane Great Britain Spain reland Norway USA New Zealand Australia FGURE 7 Estimated residual trends for national data (assuming fare elastiity of -.45 and vehile-kilometer elastiity of.45).

6 26 TABLE 2 Fator EFFECT OF FACTORS TAT AFFECT 1RAVEL Urbanization Population dispersion High-density settlements Employment deentralization Travel speed Car ownership Travel osts Transfer from two-wheeled to publi transport U.K. (?) Typial Continental Countries Short Term y y(?) y y(?) y Long Term (?) (?) NOTE: y =favors publi transport, =favors ar, - =no effetorn/a, and (?) = but ould go the other way. dispersed pallem. Transfer from two-wheelers is an important soure of publi transport patronage in some ountries, but this reservoir too must eventually dry up. Thus in the longer term, publi transport use appears to be set to deline even in those ountries where it is presently growing and where publi transport poliies might appear markedly suessful. Adoption of the same poliies in the United Kingdom would not produe the same level of growth beause the favorable fators do not eist in the United Kingdom. Estimates have been made of the likely effets of reduing or withdrawing subsidy in the various ountries, using the same assumptions about the elastiity of demand as were used in the trend analysis. Rising subsidies may have reversed a delining publi transport trend in almost one-half of the 16 ountries in the ECMT study. Only a quarter of these ountries would have retained an upward trend in the absene of subsidy and there would have been passenger loss if subsidy had not been allowed to grow. f suffiient funds were available, reversal of the trend ould be ahieved in the United Kingdom too, but this annot be a permanent solution: subsidies would have to be inreased indefinitely to maintain growth, and the underlying deline would reassert itself as soon as no further inreases were forthoming. A similar boost to publi transport use will be ahieved if "deregulation" of bus servies (under the 1985 Transport At there are no restritions, other than safety requirements, on setting up new bus servies in the United Kingdom) is suessful in reduing osts and making servies more responsive to demand: while suh improvements ontinue they will inrease patronage relative to the underlying trend, but the fundamental hanges in travel patterns desribed earlier will inevitably ontinue to redue the total market in whih publi transport has to operate. 1t therefore appears that long-term deline in publi transport use has to be aepted in the United Kingdom and will probably have to be faed eventually even in ountries where the prospets for publi transport are urrently muh brighter, but this is not to suggest that publi transport will disappear from the urban sene. The present rare of deline in the United Kingdom will slaken in the future as more pewly aquired ars are seond or third ars in the household. Foreasts using TRRL's bus predition model (5), shown in Figure 8, suggest t.hat 11\i; lotal of stage bus journ ys is likely to deline by perhaps one-quarter during the net 15 years, if tl1 eonomy grows at 1.5 perent per annum, assuming presm levels of TRANSPORTATON RESEARCH RECORD 1125 subsidy and fuel pries rising 3 perent per annum over the longer term. On the other hand, if the eonomy grows at 2.5 perent per annum, enouraging higher ar ownership and higher wages in industry, the deline ould be as muh as 4 perent. f deregulation ould ahieve an overall redution of 2 perent in unit osts, the deline would be held to between 1 and 2 perent, depending on eonomi growth. Whatever the level of deline, servies feeding ity enters are likely to remain relatively strong, but people without a private ar will find it inreasingly diffiult to get to nonentral destinations as peripheral servies beome more thinly spread. For people living in the outer suburbs (not all of whom by any means will have a ar available) aess to the enter may be more diffiult than it is today beause of longer aess distanes and less frequent servies on the outer parts of the publi transport network. 6 4!5 Cl 2 Cl. Produtivity gain in ost/km Zero 2% o._-&...a..---i Year FGURE 8 Future patronage levels on bus stnge servies n Great 13ritain under different assumptions of eonomi growth. With inreasing offie automation, the number of jobs in the ity enter is likely to deline ultimately even if the total amount of business ativity inreases. With more floorspae per employed person, the entral business distrit may look muh the same as it does today, but the density of jobs will be less. The ontinuing deline of inner-area manufaturing industry in older ities will tend to inrease the proportion of the unemployed, the old, and the disadvantaged in these areas as the young and more highly qualified members of soiety move out to take up the new, more highly skilled jobs that beome available in outer areas and in smaller towns. This will weaken the already fragile finanial base of some of these ities. n omrast, ities with a broader eonomi base, partiularly one that inludes major finanial institution or new hightehnology industry, will attrat a disproportionate share of new jobs and young, eonomially ative residents. Their enters ar likely to thrive, bm their very affluene will enourage epansion al lower residential densities, and their ability to sustain high-apaity publi tnmsport servies is bound to dimini-j-,. f srvie-e<:tor mpioymnt ontinues to grow faster in the Oltter area than in the enter, its distribution may ultimately follow the trend in manufaturing, so that lhe enters

7 Webster and Bly ease to grow and may eventually deline in servie ativities. The strength of publi transport depends substantially on the ontinuing eistene of a onentration of jobs and ativities in ity enters; if the enters deline, the impliations for publi transport, and for the struture of the ity itself, ould be serious. POSSlLE FUTURE URBAN STRATEGES The foregoing analysis suggests that there are strong underlying soial, eonomi, and demographi trends that are ausing hanges in the quality of urban life and in the mobility of the different setions of the ommunity and that it would be diffiult, if not impossible, to preserve the status quo. Even if this ould be done, the majority of the people would probably not be pleased with suh a solution beause the hanges that are taling plae are the diret result of these people's taling full advantage of their inreased affluene to widen their opportunities and improve their living standards. The argument that rising ar ownership is due to a way of life that ompels people to own ars, and that if things were organized differently ars would be both unneessary and undesired, is not onvining, given the similarity of the link between affluene and ar ownership in all ountries and environments. t appears that whatever problems mass ar ownership may bring, they will have to be oped with. Nevertheless, even the affluent setion of the ommunity will lose something as a result of the hanges that are taking plae: many people will miss the sort of urban soial life that is only possible in thriving ities with strong enters that ontain a large residential population. Those who always have a ar available are not immune to the inonvenient aspets of a arbased life-style; some of them will be in households where for reasons of age or infirmity not all members an drive and they may find themselves ating as hauffeur to an undesirable etent. But it is the 3 perent or so of the population without aess to a ar who will suffer most from the effets of mass ar ownership and urban deentralization, and it appears that the bulk of the effort in the future should be direted toward ensuring that the needs of this sizable minority are adequately met. There is also the danger that rapid hange might bring about a waste of resoures; buildings and infrastruture with years of remaining useful life might beome obsolete. What an be done? Unless serious thought is given to these issues and appropriate strategies developed in good time (many shemes have long lead times), it is likely that any measures will onstitute little more than a rearguard ation, with most of the trends ontinuing in muh the same way as at present but with a few palliatives to ease the burden on those who are most adversely affeted by the hanges. There are alternative strategies, however, that are more appropriate to the hanging situation: 1. Strategies that provide, either through redevelopment or with new onstrution, homes that are less dependent on the private ar for aess to jobs and everyday failities and 2. Strategies that slow the rate of hange of urban deentralization through positive inentives so that eisting resoures are used more effetively and there is more time for adaptation by both people and firms. The first of these strategies an be ahieved either with publi-setor housing developments or through planning ontrols that affet private developments. t may take a variety of forms: one is to have areas of mied development where residents an walk or yle to workplaes, shops, or other failities; another is to have ompat areas of housing with good transport links to equally ompat areas of workplaes, shops, and the like. Even where housing densities are not partiularly high, appropriate planning an greatly inrease the aessibility of the oupants to publi transport servies, as is the ase in Runorn (6). f the areas are planned with onentrations of homes and failities at suffiient densities to generate a high level of demand for publi transport, servies ould be self-supporting (if need be), even though subsidy might be applied for soial reasons. Residents may therefore feel seure in the knowledge that the ontinuation of their transport links does not depend on the willingness of the loal authority to subsidies servies or on the goodwill of those voluntary organizations that are being used inreasingly to operate ommunity bus servies to meet the needs of people in low-density areas. Land use alloation and transport provision must be planned together from the outset for this strategy to work. The seond strategy involves ways of slowing down eisting land use trends, partiularly those that affet the strength of the town enter beause without strong enters it is diffiult for good publi transport servies to eist. Attempts to slow these trends using highly restritive measures (e.g., land use ontrols that severely onstrit the developer's hoie, or punitive taation and priing measures that affet the loation or transport deisions of people and firms) may well be ounterprodutive in the long term as people and firms eert their right to loate where they wish to be and to travel to destinations of their hoie. f one town does not provide the required hoie it is likely that another one will. Prohibitive ontrols are likely to be suessful only if the alternatives they are supposed to enourage (whether these are development fored into alternative loations by planning restritions or travel fored onto alternative modes by priing restraints) are suffiiently attrative for people to use them not merely in the short term but also in the years ahead. Some "negative" or prohibitive ontrols, however, are bound to be neessary if a free-for-all situation is to be avoided, but where possible it is better to employ positive inentives, relying on the "arrot" rather than the "stik." Maling the town, and partiularly the town ente1, more attrative will enourage eisting firms to stay (and possibly to epand) and will attrat potential developers. t is likely that measures that are suessful in retaining employment will also be suessful in retaining people, espeially the young and more eonomially ative. The proess is self-reinforing: suessful towns tend to attrat more people and businesses and ahieve greater growth, and delining towns inreasingly lose their attration as people and businesses depart. There is also a negative feedbak element, however; the more suessful a town enter is the more likely it is to have ongestion, parking diffiulties, higher rents, and so forth, whih, if left unheked, will eventually slow down the town's growth. This may not be viewed as neessarily undesirable in those ases in whih there are advantages to hanneling further growth into other towns. 27

8 28 n most ases, however, these problems will be takled using the usual remedies of new road onstrution, provision of etra parking spaes, and improvements in publi transport (new metro systems, provision of bus lanes, better servies, et.). The optimum balane between improvements in publi transport and improvements in the road network depends on the etent to whih people with a ar available are likely to forgo the use of the ar and use publi transport instead to gain aess to town-enter ativities. This in turn depends on both the attrativeness of town-enter destinations and the quality of publi transport. High quality in just one of these aspets is generally not suffiient to entie drivers from their ars; both are normally neessary. Thus, in towns that are delining, provision of ostly new transport infrastruture may fail to attrat new users in suffiient numbers and the investment may only serve io aeleraie ihe deline if it plaes additional finanial burdens on an authority that is already in finanial diffiulty. n these towns, however, lower ongestion, easier parking failities, and lower rents an be used as bait to attrat new development, provided redevelopment an be done on suh a sale that it is not devalued by any remaining derelition. Sensitive redevelopment, whih aepts the desire for lower densities and use of the ar where this is appropriate and makes the best use of any natural features, suh as rivers, anals, hills, open spaes, and buildings of arhitetural or historial merit, has been markedly suessful in many ases. Suh improvements are unlikely to reverse the outward movement of people and jobs but may at least slow down the eodus to manageable proportions while reating a muh more pleasant environment for those who remain. Redevelopment on the sale suggested here requires a ombination of omprehensive planning, involvement of the private setor, and hanneling of market fores beause urban eonomis tend to be governed by the large sale of private rather than publi investment. Suh redevelopment requires that inner-ity land not be overpried beause of histori "book values" (otherwise private developers will be frightened off) and that developable land be put together in suffiiently large parels, despite the institutional problems, for the plans to be arried through at a reasonable pae. f attempts at redevelopment are too long delayed, the eodus of people and jobs will make renewal even more problemati, espeially beause it is the more ative and affluent members of the ommunity who are also the more mobile. CONCLUSON Urban travel patterns are hanging, and fators that enourage the use of the private ar are likely to remain important into the foreseeable future, with an inreasing share of travel taking plae in nonentral areas and in smaller towns. Conversely, those fators that presently favor publi transport use in some ountries are likely to diminish in the longer term so that there, as in the United Kingdom, publi transport use appears to be about to deline. TRANSPORTATON RESEARCH RECORD 1125 nreasing subsidies an ombat this trend but only at an ever-inreasing ost, and the deline would reappear as soon as subsidy stopped inreasing (redutions in operating ost would also boost publi transport use but would only raise the level from whih the deline ours). The mehanisms underlying the deline are onneted with hanging patterns of land use and urban development, and these are so fundamentally tied to inreasing affluene and ar ownership, and to industrial reorganization, that it is neither feasible nor desirable to reverse them. t is more realisti to aknowledge that the size, funtion, and struture of ities are bound to hange and to aept the dispersion of people and jobs away from large towns as an opportunity to redevelop the inner areas in a way that is ompatible with people's requirements for more spae and more mobility. ntegration of the planning of land development and transport failities an improve the mobility of people who do not have aess to a private ar, and, it neessary, finanial support an be hanneled into those areas where it is most needed, either to support etra transport servies or to atalyze redevelopment more suited to the new onditions. ACKNOWLEDGMENT The work desribed in this paper forms part of the program of the Transport and Road Researh Laboratory and the paper is published by permission of the Diretor. Crown opyright. The views epressed in this paper are not neessarily those of the Department of Transport. REFERENCES 1. F. V. Webster, P. H. Bly, R.H. Johnston, N. Paulley, and M. Dasgupta Changing Pallerns of Urban Travel. Report to the European Conferene of Ministers of Transport. OECD Publiations, Paris, World Road Statistis. nternational Road Federation, Geneva, Switzerland, annual. 3. R H. Johnston. Travel Charateristis of Seven Frenh Cities. TRRL Report LR 116. Transport and Road Researh Laboratory, Crowthorne, Berkshire, England, S. Fothergill and G. Gudgin. Unequal Growth: Urban and Regional Employment Change in the UK. Heinemann, London, England, R. H. Oldfield, P. H. Bly, and F. V. Webster. Prediting the Use of Stage Servie Buses in Great Britain. TRRL Report LR 1. 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