Assessing national urban transportation policy alternatives

Tronspn Res., Vol. 10, pp. 15%178. Papmoo

Press 1976. Printed in Great Britain

ASSESSING NATIONAL URBAN TRANSPORTATION POLICY ALTERNATIVES EDWARDWEINER Officeof TransportationPlanningAnalysis,Officeof the Secretary,U.S. Departmentof Transportation,400Seventh StreetSW,Washington,DC20590,U.S.A. (Receiued 16July 1975) Abstract-This paper describes a model for assessing national urban transportation policy alternatives and its application in the 1974National TransportationStudy in the U.S. This multimodal version of the TRANS-Urban model system employs an aggregate modelling technique which treats each urban area as a single analysis unit. Given a level and mix of funds, the model calculaks the amount of highway and transit facilities, travel demand by mode, system performance, and external impacts such as fatalities, land consumed, air pollution, dislocations and energy consumed. The model was applied to assess the effects of alternative funding and pricing policies for the 64 largest

urbanized areas.

INTRODUCTION

Over the years, the United States government has conducted large scale national surveys as one basis for determining future national transportation “needs”, policies and programs. The most well known of these surveys is the National Highway Needs Study which has been conducted on a biennial cycle since 1968 (U.S. Department of Transportation 1970and 1972a).Traditionally these “needs” studies have been conducted on a unimodal basis. More recently, the Department of Transportation has evolved a multimodal National Transportation Study process which considerably broadens the scope of these national studies (U.S. Department of Transportation 1972b and 1974). The latest of these, the 1974 National Transportation Study, covered all major modes of transportation, and included information on system extent and performance, travel demand, social and environmental impacts as well as capital and operating costs. These data were obtained on a consistent basis across three time periods; 1972 Inventory, 1972-1980 Program and 19721990 Plan. The study process involved State and local elected officials including the Governors of each State (Weiner, 1974b and Mongini, 1972). The multimodal 1974 National Transportation Study represents a considerable improvement over previous unimodal efforts and is thereby more useful for developing future national transportation requirements, policies and programs (Swerdloff and Mongini, 1974). However, the 1972-1990 Plans submitted by the States and urbanized areas represent only one scenario of the nation’s future transportation system. This information would be even more useful if the State and urban transportation plans were assessed and compared with other possible alternatives. There are two approaches to the development and assessment of future national transportation alternatives. The first approach is to request that the States and urban areas develop and submit these alternatives, perhaps with the Federal government specifying guidelines for the

alternatives. Such an approach was utilized in the 1972 National Transportation Study (U.S. Department of Transportation 1971, 1972b; Weiner 1971, 1974a; Swerdloff, 1972).The problem with this approach is that it places a large additional workload on the States and urban areas, which found the reporting requirements for the single alternative burdensome (Peyrebrune, 1974). In addition, requesting that the States and urban areas prepare additional alternatives would severely restrict the number of the alternatives that could be assessed. A second approach would be to develop and analyze the alternatives at the Federal level. This is the purpose for which the Transportation Resource Allocation Study (TRANS) Model was developed. Even though there is a loss of detail by using such a model, the advantage in terms of the increased number of alternatives that could be analyzed, the lower cost and effort required and, the flexibility in performing these analyses far outweigh the limitations. It is, however, recognized that the TRANS model is probably inappropriate for the analysis of some urban policy issues. For example, the model is not appropriate for analyzing corridors and facilities in individual urban areas nor for assessing alternative land use distributions in specific areas. MODEL

Evolution of the model

Earlier versions of the TRANS model represent developmental stages of the TRANS-Urban methodology (Kassoff and Gendell, 1971). These versions were basically highway oriented models primarily concerned with treating highway investment tradeoffs under varying transit usage assumptions. A later version of the model incorporated: the capability to analyze central cities and suburbs separately; an improved demand forecasting module; an analytical model for estimating the distribution of travel between freeways and surface arterial% and, the ability to analyze travel by time of day (Gendell, et al., 1973; Gendell, 1973). This version of the TRANS model was used to analyze policy alternatives for the 1972 159

E. WEINER

160

The structure of the TRANS-Urban model, as it is applied to each urban area individually, is shown in Fig. 1. The application begins with the specification of a level of investment and within each level the mix of funds among four types of transportation supply; freeways, surface arterials, conventional bus and rapid transit (both bus and rail). Travel projections are made on the basis of both socio-economic variables and the nature and extent of the transportation system supply alternative. The travel is distributed by mode and time of day, with system performance measures (such as speed) estimated on the basis of the interaction between supply and travel demand. User effects (such as changes in travel time) are calculated for each mode, along with external effects (such as fatalities, dislocations, air pollution einissions, and gasoline consumption).

National Highway Needs Study (U.S. Department of Transportation, 1972a). The current stage of development, the multimodal TRANS-Urban model, extended the scope of the earlier versions of the model by incorporating the capability to simultaneously assess highway and transit alterhatives (Weiner, et al., 1973; Weiner, 1973). This version of the TRANS model was applied in the 1972 National Transportation Study to assess the effects of 12 altemative levels and mixes of capital funds for highways and public transportation for the 63 urbanized areas which will be over 500,000 in population by 1990 (U.S. Department of Transportation, 1972b). Since this application of the model, several refinements have been made, most notably the inclusion of an energy consumption module. Overview of the model

Specification

The TRANS-Urban Model system is a set of analytical procedures for evaluating alternative levels and mixes of transportation investments in urbanized areas. The model operates at an aggregate level, treating each urban area as a basic unit of analysis. It is capable, however, of treating in a single application every urbanized area in the nation.

URBAN

FREEWAYS

AREA

of an investment alternative

An investment alternative is specified for each urban area by a level of capital expenditures and a percentage split of these expenditures among four types of transportation facilities; freeways, surface arterials, conventional bus and rapid transit (both bus and rail). The investments

INVESTMENT

LEVEL

RAPID TRANSIT

CONVENTIONAL

SURFACE

BUS

ARTERIALS

TARGET YEAR TRANSPORTATION SUPPLY ALTERNATIVE

-

BY MODE

t SYSTEM

PERFORMANCE

-

Fig. 1. TRANS-Urbanmodelsystem.

EXISTING

TRANSPORT SUPPLY

Assessingnationalurban transportationpolicyalternatives

existing outlying rural facilities.) The fourth alternative adds a specified minimum supply of conventional bus service for the 1972-1990 growth area. The analysis of the fifth alternative, which is the one that has been specified, begins by subtracting the costs of the third and fourth alternatives for surface arterials and conventional bus from the specified level of investment. The remaining funds are then used to calculate the additional supply of facilities and equipment for each submode which is added to the existing supply. This is the supply level which is carried into the later steps of the analysis.

represent total expenditures for each mode and submode over the entire forecast period. By applying unit costs to the investment in each category, the total additional supply provided between the base and target years is calculated. The additional capacity is then added to the base year (existing) supply for each submode yielding the total supply available in the target year. The model increments through four alternatives before analyzing the investment alternative which has been specified. The first alternative (which is not really an alternative as such), operates on base year conditions and performs an evaluation of system performance (speeds, operating costs, accidents, mode split etc.) under current supply levels. The second alternative examines the “do-nothing” case under which future travel projections are derived assuming no additional facilities are added to those existing in the base year. Alternative three involves the addition of a specified minimum supply of surface arterials to-be provided for the growth area between the 1972 and 1990 urban boundaries. (The unit costs associated with this minimum supply of surface arterials assumes that these roads will be reconstructed from

Estimation of total travel Inthe current application of the TRANS-Urban Model, total person trips are calculated from the vehicle miles of travel (VMT) and base year transit trips estimates prepared by the States and urbanized areas. A step by step description of this process (shown by the flow diagram in Fig. 2) follows: 1. Projected VMT is separated into internal auto, truck

ARTERIAL VMT PROJECTION FOR URBANIZED

PERCENT

INTERNAL

AUTO

161

AREA

w

VMT

INTERNAL

AUTO

ARTERIAL

THRU

VMT

AND

TRUCK

VMT

I

AVERAGE

TRIP

LENGTH

-

INTERNAL PERSON

TOTAL

AUTo TRIPS

INTERNAL

PERSON

I

1

AUTO

(TREND-CONSTANT

I

PEAK/OFF

OCCUPANCY

TRANSIT

-c

TRIPS

I t-i

-

NON-WORK

PEAK DISTRIBUTION BY PURPOSE

Fig, 2. Estimation of internal person trips.

TRIPS

TRIPS NUMBER)

162

E. WEINER

and through travel by applying factors developed from urban transportation study data. 2. Internal auto VMT is converted to internal auto person trips using overaIl average trip lengths and car occupancy rates. 3. Total projected internal person trips are calculated by adding internal auto person trips to base year estimated transit trips. Once these transit trips are merged with auto person trips they lose their identity, and the entire sum of internal person trips is subjected to the mode split analysis, described in the next section. 4. Daily total internal person trips are stratilied by two trip purposes (work and non-work). 5. Trips by purpose are stratilied into peak and off peak trips. 6. The mode split model is applied to peak and off peak trips, by purpose, excluding hours between midnight and 4 a.m. 7. Transit trips are analyzed in the transit performance subsystem of the model. Auto trips are converted back to daily vehicle miles, combined with through and truck VMT, and analyzed in the highway performance subsystem. Estimation of mode split The development of a macro-level (areawide) mode split model represented the key to providing the TRANS-Urban model with a true multi-modal capability (Bellomo, 1972). The macro-model was formulated utilizing data from micro-level simulations using a hypothetical urbanized region of 2.5 million persons, and a generalized micro mode split model (applied to zone-to-zone trip interchanges) developed from actual applications to three real cities. Micro -mode split model used in development of macro model. Thirteen test situations were formulated using the hypothetical urban region. The tests covered a range of both highway and transit levels of services, and two types of urban activity patterns. Three types of transit alternatives were considered; (1) conventional bus only, (2) bus rapid (combined with conventional bus), and (3) rail rapid (combined with conventional bus). The micro mode split model used in the analysis estimation transit usage on the basis of (1) relative levels of service between private automobile and transit, (2) automobile ownership, and (3) trip purpose (i.e. work and non-work). The relative system service levels were estimated on the basis of the utility function shown below: U=25(Ta+Tw-At)+(Tr-Ar)t(F-OSP-DxM)/C where U = Marginal utility Ta = Walk time to/from transit Tw = Wait time for transit Tr = Running time for transit F = Transit fare At = Auto terminal time Ar = Auto running time P = Parking cost D = Highway distance C = Cost of time (assumed as to 25% of income) M = Auto mileage cost.

The concept of the micro-level model is that transit usage depends upon the relative service levels between the private auto and transit modes. The model relates the marginal utility between the two modes (on the basis of traveltime and travel cost parameters) to transit use. The application of the micro model to the 13 test systems produced a set of aggregate, areawide data containing information on travel demand, system performance, and system supply. Utilizing these data, a group of aggregate level relationships were d&eloped to provide the TRANS-Urban model with the necessary macro level modeling capability. Macro mode split models (Fig. 3). The macro-level mode split models consist of families of curves which relate areawide percent of internal person trips via transit to areawide traveltime and travel cost differences between transit and automobiles. The models are stratified by trip purpose (homebased work and other) and by time period (peak ‘and off peak) (Bellomo, 192). Since the models were developed on the basis of a hypothetical city of 2.5 million persons, their application in TRANS is limited to only the largest urbanized areas (greater than 500,000population). The aggregate mode split models are applied to the peak/off peak and home based work and other internal person trips, which were estimated previously. Figure 4 shows the macro mode split relationships for peak work trips. As mentioned earlier, transit trips are then analyzed in the transit performance submodel while auto trips are converted to vehicle miles of travel and incorporated with truck and external VMT, yielding total area VMT, to be analyzed in highway performance submodel. Driving the macro models are four basic inputs-traveltimes and travel costs for automobiles and transit. 1. Automobile traveltime. Within each alternative, automobile traveltimes are estimated using an iterative approach. For each supply alternative, the model initially assumes that all internal person travel will be via automobile. Having made this assumption, a first estimate is made of average overall travel speed on highways for peak periods. These speeds are converted, through estimated average trip length, to average time per internal auto person trip, which is then used in the mode split model. After the mode split calculation is made, highway travel is reassembled and highway speeds recalculated using the highway subsystem and compared to the speed used going into the mode choice analysis. If the speeds match within a specified tolerance, the model proceeds normally. If the speeds fail to match, an adjustment is made to provide a new input speed estimate, and the mode split rerun. This process continues until the input and final speeds actually balance within the tolerance limit. 2. Transit traveltime, Transit traveltimes are estimated utilizing equations based upon the relationship between peak transit traveltime (minutes) and transit supply per capita. The equations were developed to account for the e&t on transit traveltime of levels of transit supply which differ from those inherent in the 13 system tests as well as to incorporate logical minimum and maximum traveltimes. Off peak transit traveltimes are derived using a relationship which relates off peak times to peak

Assessing nationalurbantransportationpolicy alternatives

HIGHWAY HIGHWAY

TRIP TRIP

TIMES COSTS

p

MODE

SPLIT

AUTOMOBILE PERSON

MODEL

TRANSIT TRIP TIMES TRANSIT FARES

4

TRANSIT

TRIPS i

PERSON

TRIPS

AVERAGE TRIP LENGTHS

TRANSIT

TRANSIT SEAT MILES FOR CONVENTIONAL BUS AND RAPID TRANSIT

PERSON

MILES

SUEMODAL SPLIT MODEL

Fig. 3. Modesplitandtransitperformancesubmodels. traveltimes based upon relative transit supply in the two periods, and based upon level of highway supp1y.t 3. Automobile travel costs. Costs per internal auto trip for the purposes of the mode split analysis include perceived vehicle running costs and parking costs. Perceived running cost per vehicle mile is divided by vehicle occupancy and multiplied by the average trip length (by trip purpose) yielding the rumring cost per trip. This cost, which is initially input on a per vehicle trip basis, represents an estimate of the sum of all parking costs incurred *(by trip purpose for peak and off peak periods) divided by the sum of all trips taking place (by trip purpose for peak and off peak periods). Parking costs are calculated external to the model by estimating the percentage of auto trips in a metropolitan area which end in the central business district (CBD), by trip purpose and in the peak and off peak periods. It is assumed that only CBD trips incur parking costs. The actual parking fee which is charged is then multiplied by this percentage to arrive at an average cost spread over -all internal Where relationshipsas well as the family of macro-levelmode choice curves are presentedin Bellomo et al. (1!372).

automobile trips within a particular trip purpose and time period. A vehicle occupancy factor is then applied to convert to cost per person trip. 4. Transit travel costs. The perceived cost to transit users is represented solely by the average areawide fare. Transit fares are specified separately for peak and off peak periods. In summary the macro level mode choice model is applied to each urbanized area for each supply altemative, and produces estimates of the split of internal person trips between the transit and automobile modes for work and non-work tips for peak and off peak periods. Estimation of transit performance and submode split Following the mode split analysis for each investment level and unique mix of investments, an analysis is performed of transit performance and submode split (Fig. 3). This consists of computing transit person miles of travel, performing a “sub-modal” split, and calculating load factors by sub-mode. Transit person miles. Transit person miles of travel are computed by multiplying transit trips by average trip length. The home based ‘work trip length is derived from

E.

164

WEINER

PEAK 5.

PERCENT

RAPID

SEAT

MILES

Peak percent rapid passenger miles of travel vs peak percent rapid seat miles.

specified maximum load factor. This is done for peak and off peak time periods for both sub-modes. -5

0 PEAK

5 TRAVEL

10 TIME

15

20

DIFFERENCE

25

30

35

(MINUTES)

(TRANSIT-AUTO)

Fig. 4. Macro mode split relationships for peak work trips.

the equation for that trip purpose, while the trip lengths from the home based non-work and the non-home based equations are weighted to obtain an average trip length for the “other” trip category. Sub-modal split. The macro mode split model is bi-modal; i.e. it distinguishes between basically two modes of travel-automobile and transit. In order to determine the allocation of transit travel to conventional bus and to rapid transit systems, when the two are considered simultaneously, the model utilizes a sub-modal split analysis which was developed from the series of simulations performed to obtain the macro mode split model. The sub-mode split curves are shown in Fig. 5 for rail and bus rapid systems. According to the data from which the curves were developed, a given share of seat miles of transit supply on bus rapid attracts a greater share of the transit market than that attracted by the same share of seat miles on a rail rapid system. This is perhaps a reflection of the ability of bus rapid systems to perform a collection/distribution function as well as provide rapid line haul service. (In fact, the rapid bus seat miles include those seat miles which occur during collection and distribution of passengers on conventional streets.) -. The sub-mode split curves were developed only for peak periods. For lack of any data, it is assumed that they apply to off peak as well, although the model is capable of accepting any other assumed or derived relationships. Calculation of transit load factors. Based upon the allocation of passenger miles to each of the two transit sub-modes, the ratio of passenger miles to available seat miles, by sub-mode is calculated and compared to a

Estimation of highway system performance

Once the mode split process is completed for peak and off peak periods, highway travel is “reassembled” for the full day. This involves converting internal automobile person trips (which are output from the mode choice model) to internal automobile vehicle miles of travel, estimating truck and external vehicle miles, and applying a factor to calculated arterial vehicle miles of travel (on freeways and surface arterials). Figure 6 is a flow diagram of this pocess. Whereas the mode split process and the transit performance submodel operate on the basis of three time periods (peak, off peak, and the “wee hours” during which there is no transit service), the highway performance submodel is capable of dividing the average day into as many as 24 hour periods. The TRANS-Urban model utilizes a stratification of 20 time periods throughout the day (Hill et al., 1973). Within each time period travel is allocated to each of two directions. This directional stratification recognizes that while system capacity is usually fairly evenly split SO/SOby direction within most hours of the day highway travel is not, particularly during peak hours. Thus, for each time period a directional factor is applied which stratifies total arterial travel into two categories; the first accounting for radial and Circumferential travel in one direction, and the second accounting for travel in the opposite radial and circumferential direction (Hill et al., 1973). Within each hour period and direction the model computes the ratio of highway travel to available highway capacity. The ratio is then compared to specified maximum travel to capacity ratios for each time period. If the latter is exceeded, the model attempts to redistribute travel to prior and subsequent hour periods (in specified proportions) having excess capacity. If all hour periods are at this maximum level of congestion, the program prints an appropriate message.

165

Assessingnationalurbantransportationpolicy alternatives

AUTOMOBILE

PERSON

TRIPS I

TRUCK VEHICLE MILES EXTERNAL VEHICLE MILES

TOTAL VEHICLE MILES (VMT)

-

VMT

*

AUTO OCCUPANCY FACTORS AVERAGE TRIP LENGTHS

DISTRIBUTION

BY HOUR

PERIOD

I RE-DISTRIBUTE

DIRECTIONAL

VMT

ALLOCATE

VMT

SPLIT

VMT

TO SYSTEMS

SYSTEM

PERFORMANCE

BY TIME

OF DAY,

BY FACILITY

BY DIRECTION

TYPE,

OF TRAVEL

Fig. 6. Highwayperformancesubmodel.

After arterial highway travel has been distributed by hour and direction the model allocates travel to the two classes of arterial facilities-surface arterials and freeways. This is accomplished through the use of a “functional splitter”. The functional splitter allocates travel to freeways and surface arterials based upon relative speeds on the two types of roads, overall average trip length, average ramp spacing, and the relative supply of freeways and surface arterials (Creighton-Hamburg, 1971). With daily arterial travel stratified according to 20 time periods, two.directions, and two facility types, the TRANS-Urban model is able to estimate indicators of highway system performance for 80 individual categories. Systemwide travel to capacity ratios are calculated and used to estimate average freeway and surface arterial overall travel speed. Also estimated are vehicle running costs, which vary by speed and facility type, (and are based on speeds) traveltime costs (based upon a specified composite private auto/truck value of traveltime per vehicle hour). Total user costs are summed within and

across all hour periods, directions, and facility types, producing an estimate of total daily user costs on the highway system. These costs along with various performance indicators such as peak hour and daily speeds, and peak hour and daily travel to capacity ratios, are reported in the output. Estimation of extemal impacts A number of external impacts are estimated in the TRANS-Urban model. These include: (i) Number of annual fatalities; (ii) Number of residential dislocations; (iii) Number of business dislocations; (iv) Square miles of land consumed; (v) Daily tons of three types of air pollutants-carbon monoxide, nitrogen oxides and hydrocarbons; (vi) Daily gallons of gasoline consumed These impacts are calculated by multiplying rates times the relevant extensive variable which describes the alternative being analyzed. For example, fatalities are computed using annual fatality rates per VMT for the four types of facilities, freeways, surface arterials, conven-

166

E. WEE-IER

tional bus and rapid transit. These rates are multiplied by the VMT for each facility type and summed to a total number of annual fatalities for that particular alternative. The number of residential and business dislocations and square miles of land consumed are calculated using rates per mile of each type of facility. Typical cross sections are assumed for these estimates. Air pollution emission factors are applied by pollutant type, vehicle type and speed. The factors are multiplied by the VMT in each category to estimate total emissions by type. The gasoline consumption computation utilizes average gallons per mile factors times VMT. All of these factors specified can be readily changed to test the sensitivity of different assumptions. APPLICATIONOF THE MODEL The

TRANS-Urban Model was applied in the 1974 National Transportation Study to evaluate the implications of four general types of alternatives: (i) Alternative investment; (ii) Alternative (iii) Alternative fares; (iv) Alternative

proportions of highway and transit level of total investment; peak-hour parking rates and transit automobile occupancy rates.

The analyses were conducted for the 64 urbanized area with populations of 500,000 or greater in 1990.This group was chosen because of the greater likelihood that there would be major decisions on highway-transit tradeoffs. Limitation of the analytical approach The TRANS-Urban model is useful method for analyzing alternative urban transportation programs and policies on a nationwide level. However, in any analytical approach certain simplifications and exclusions have to be made so that the analysis task is manageable. These factors must be taken into consideration when interpreting the results. First, in this approach, each urban area was treated as a single analysis unit. Results, then, are areawide averages. No attempt was made to determine how the results vary within urban areas. Second, since the analysis was performed on a nationwide basis, the results are most valid for the Nation as a whole or for groups of urban areas. Third, several factors were held constant over the analysis period, 1972-90, to maintain comparability of results and because of the difEculty of forecasting changes in these factors. These factors include fatality rates, gasoline consumption rates, residential and business dislocation rates, as well as capital and operating costs. All these factors would probably change over the B-year analysis period, and would probably change at different rates for the various transportation modes. Fourth, several factors were held constant between the various alternatives tested. In particular, the totrrl number of trips in each urban area was not varied. In practice, as the level of funds and supply of transportation increase, an increase in the number of trips would be expected.

Alternativeproportions

of highway and transit investment

Five alternative findings programs were evaluated in order to provide a broad spectrum for comparison. These programs were expressed by a given total dollar level and a percentage split of funds among four types of transportation facilities-freeways, surface arterials, conventional bus, and rapid transit (either bus or rail). Five alternative programs were evaluated for the l&year period, 1972 to 1990. The Alternatives are as follows: (i) 1990 Plans Alternative, percentage of funds were allocated to the various modes according to the capital investments indicated for each individual urbanized areas in their 1990 Plans submitted as part of the 1974 National Transportation Study. (ii) Mode Split Alternative, percent of all person trips by each mode was used as the basis for allocating funds. Thus, if an urbanized area indicated that 8% of all person trips would be made by rapid transit, then 8% of the funds were so allocated. (iii) High Highway Alternative, all the funds were allocated to freeway, and surface arterials. Only the minimum funds necessary to maintain current supply of transit in an expanded service area were channeled into transit. (iv) High Transit Alternative, this alternative was just the reverse of the High Highway Alternative. All funds were allocated to rapid transit (bus and rail) and conventional bus, and only the minimum amount of funds necessary to cover the expanded-service area were allocated to freeways and surface arterials. (v) Equal split alternative, half of the funds were allocated to transit (bus and rail) and half the funds were allocated to highways (surface arterials and freeways). Within each mode, funds were allocated in the same proportions shown in the 1990 Plans Alternative. Table 1 shows the average allocation of funds in each mode for all ubanized areas represented in the analysis. Only one level of funding was assumed for all five alternatives shown in Table 1. This level is the total of the capital expenditures for the four modes used in this analysis as reported by the States and urbanized areas in their 1972-90 Plans. This total amounted to $160billion, in constant 1971 dollars, for the 64 urbanized areas. System supply. The various funding allocations would result in significantly different changes in facilities for the 1972-90 period. Figures 7 and 8 show that percent changes in freeway and surface arterial miles would be greatest under the Highway Alternative. Miles of freeways would increase 358% and miles of surface arterials would increase 70% over 1972conditions, under the High Transit Alternative, however, no freeways or surface arterials would be added to the existing system. Although most of the money under this alternative would be allocated to transit, the analytical technique nevertheless takes a portion of the total capital investment and applies it to the construction of highways. Therefore, even an hypothesized policy of high-transit investment would maintain the highway system at some minimum level. The 1990 Plans Alternative would produce an increase in freeways miles of 152%and, the investment strategy based on person-trip

167 Table 1. Allocationofhndsamongmodesforaltemativetransportationprograms,percent Alternative

of funds*

Rapid Transit

Conventional Bus

Total Transit

SIllfaCe Arterials

Freeways

Total Highway

27 4 1 48 41

6 6 1 48 9

33 10

35 54 49 2 26

32 36 49 2 24

67 90 98 4 50

1990Plans Mode Split High Highway High Transit Equal Split

; 50

*Average percent allocation for all 64 urbanized areas over 500,000in population in 1990.

ALTERNATIVE TRANSPORTATION PROGRAMS

1

1990 PLANS

I

MODE SPLIT

I

HIGH HIGHWAY

HIGH TRANSIT

I

EOUAL SPLIT

I

I

I -4eo

a0

-se0

I

I

I -100

I

I

I

I

+100

0

+200

+300

+400

PERCENT CHANGE 1972.90 NOTE 1972 MILES OF FREEWAYS = 9,579

Fig. 7. Percent change in miles of freeway for alternative transportation programs, 1972-90.

ALTERNATIVE TRANSPORTATION PRGGRAMS

1990 PLANS

MODE SPLIT I

HIGH HIGHWAY

HIGH TRANSlT

EGUAL SPLIT I 1,

40

I

-70

I

-80

I

-60

I

-40

I

-30

I

-20

I

-10

0

I +,o

I +20

I +30

I +a0

I 60

I *o

PERCENT CHANGE 1072.90 Nob

,972

MILES OF SURFACE ARTERIAL9=75.380

Fig. 8. Percent change ip miles of surface arterials for alternative transportation programs, 1972-90.

I +70

I +*o

168

E. WEINER

Mode Split would yield a large percent increase in freeways of 358%. For rapid transit, the greatest percent increase in line miles as shown in Fig. 9, would occur of course under the High Transit Alternative. This increase would be 662% over the 1972 Inventory and includes both rapid rail line-miles and miles of bus rapid rights-of-way. No rapid line-miles would be added under the High Highway Alternative. When investment is allocated on the basis of person trip Mode Split, only a 64% change in rapid transit line miles would result. Under the 1990Plans Alternative, a 355% increase would occur.

Speeds and trak4 times. Figures 10 and 11 display the percent change that would occur in areawide daily highway speeds over the 1972-90 period and. the percent changes in peak-hour auto trip times for the same period under the five funding alternatives. As the proportion of funds allocated to highways increases, the average automobile speeds and travel times would improve-this is the result of additional highway facilities being provided. For automobiles, the greatest improvement of course would occur under the High Highway Alternative. Average daily highway speed would improve 26%.

ALTERNATIVE

TRANSPORTATION

1990 PLANS

MODE SPLIT

HIGH HIGHWAY

HIGH TRANSIT

EQUAL SPLIT I

I -700

I -600

I -500

I

I -400

I

-300

-200

I

t

-TM)

0

I +rgo

I +200

I

I

I +390.

+400

+5w

I +600

PERCENT CHANGE 1972-w NOTE 1972 RAPID TRANSIT LINE MILES-

3109

Fig. 9. Percent change in rapid transit line-miles for alternative transportation programs, 197240.

ALTERNATIVE TRANSPORTATION PROGRAMS

1

1990 PLANS

MODE SPLIT I

HIGH HIGHWAY I

HIGH TRANSIT

EQUAL SPLIT I I -30

I -2s

I -20

I .lS

I .lO

I .!j

0

I +6

I +10

I +15

I +20

I +25

I +Jo

PERCENT CHANGE 1972-W NOTE 1972 AVERAQE DAILY HIGHWAY SPEED = 38.2 M.P.H.

Fig. 10. Percent change in average daily highway speeds for alternative transportation programs, 1972-90.

I t700

Assessing national urbsn transportation policy alternatives

169

ALTERNATIVE TRANSPORTATION PROGRAMS lee0 PLANS

MODE SPLIT

HIGH HIGHWAY I

HIGH TRANSIT I

EOUAL SPLIT I I -15

I -10

I -5

0

I ffi

I +10

I +15

PERCENT CHANGE 1972.SC NOTE 1972 AVERAGE PEAK-HOUR AUTOMOBILE

TRIP TIME = 20.2 MINUTES

Fig. 11. Percentchangein peak-hour automobile trip times for alternative transportation programs, 1972-90. Similarly, the greatest improvement in peak-hour automobile trip times would occur under this alternative. Significant improvements in automobile speed also would occur under the 1990 Plans Alternative, the Mode Split Alternative, and Equal Split Alternative. The least improvement would occur under the High Transit Alternative. This same pattern would prevail for peakhour automobile trip times. The trip would decline 2.9% for the Mode Split Alternative and 4.5% for the High Highway Alternative. Auto trip times would worsen 3.5% under the 1990 Plans Alternative and the 9.7% under Equal Split Alternative. Predictably, under the High Transit funding alternative automobile trip times would be the longest; they would increase by 10.5%.

Figure 12 displays similar information for peak-hour transit trip times. Transit trip times would improve for three funding alternatives-13.4% for the 1990 Plans Alternative, and 12.7 and 6.2% respectively, for the High Transit and Equal Split Alternatives. All other funding alternatives would result in an increase in transit trip times. Modal split. Modal split (Fig. 13), or the distribution of trips among the highway and transit modes, would vary considerably under the various funding allocations. Under the High Transit programs, daily modal split would increase 32.4% over the 1972 conditions. Smaller increases of 24.4% would occur under the Equal Split Alternative and 10.3% for the 1990 Plans Alternative. A

MODE SPLIT

HIGH HIGHWAY I

HIGH TRANSIT I

EGUALSPLIT

j

1

,

,

-15

-10

r;-1

.5

0

,

,

,

+5

+10

+15

PERCENT CHANGE 1972.90 NOTE 1972 AVERAGE PEAK-HOUR TRANSIT TRIP TIME = 38.8 MINUTES Fii.

TX. 10/3-C

12. Percent change in peak hourtransit triptimes foralternative transportation programs, 1972-90.

E. WEINER ALTERNATIVE TRANSPORTATION PROGRAMS 1990 PLANS

I

MODE SPLIT I

HIGH HIGHWAY

1

HIGH TRANSIT I

EGUAL SPLIT I I

I

I

I

-30

-20

-10

I

+10

0

t20

+24

PERCENT CHANGE 1972.90 NOTE 1972 DAILY MODAL SPLIT (DAILY PERCENT OF TOTAL TRIPS BY TRANSIT) = 7.1

Fig. 13. Percentchangein dailymodrilsplitfor alternativetransportationprograms,1972-90. 16.3% decrease in mode split would result when funds are allocated on a person-trip Mode Split basis. Transit trips would increase under all the finding alternatives (Fig. 14)., The two largest changes would occur under the Equal Split Alternative, which would have a 6% increase, and under the High Tratlsit Alternative, where a 79.8% increase would occur. Under the Mode Split and High Highway Alternatives, however, the increases would only be 11 and 9.9%, respectively, the 1990 Plans Alternative results to fall roughly in between, with an increase of 49.6% over 1972 conditions. Dislocations. The number of residental and business dislocations that would result from the five alternatives

are shown in Figs. 15 and 16. The number of dislocations would be directly related to the proportion of funds allocated to highways. As the miles of new facilities increase, so would the number of dislocations. The increase in both residential and business dislocations would be greatest under the High Highway Alternative and lowest under the High Transit Alternative. The differences would be substantial; the largest number of dislocations would be three to four times the smallest number. Land consumed. Figure 17 shows the amount of land in square miles that would be taken to construct transuortation facilities under the various alternative f&ding

ALTERNATIVE TRANSPORTATION PROGRAMS lS90 PLANS

MODE SPLIT

HIGH HIGHWAY

HIGH TRANSIT

I

I EGUAL SPLIT I

1

1 -m

I -so

I

I

-50

-40

I

I

I

-30

-20

-10

I 0

I

I

I

I

I

I

+10

+20

+30

+40

+5l

PERCENT CHANGE 197300 NOTE 1972 DAILY TRANSIT TRIPS = 17,hS.Doo

Fig. 14. Percentchangein dailytransittripsfor alternativetransportationprograms,1972-90.

I +So

I t70

171 ALTERNATIVE TRANSPORTATION PROGRAMS loo0 PLANS

MODE SPLIT

HIQH HIQHWAV

HIGH TRANSIT

EOUAL SPLIT

I

I

do00

-woo

I

I

I

I

+1000

+2W0

+3000

+4000

I

I

-1SOO

-2mo

0

RESIDENTIAL DISLOCATIONS m0USAN0sl1972-1990

Fig. IS. Changein totalnumberof residentialdislocatioasfor alternativetransportationprograms,1972-W.

c,

ALTERNATIVE E&R_TATlOL

WSOPLANS

MODE SPLIl

I

I

HIGH HIGHWAY

HIOH TRANSIT

I

SGUAL SPLIT I

I

I

I

I

180

-1S0

-140

-120

-im

I

-80

I

I

-60

40

0

I

I

+40

+S0

I +m

I +100

I +120

I +140

I +1S0

1 +1S0

BUSINESSDISLOCATIONS 1972-80

Pii. 16. Changein totalnumberof busiiss dislocationsfor alternativetransportationprograms,1972-90. programs. The High Highway Alternative would consume the most amount of land fohowed by the Mode Split Alternative and the 1990 Plans Alternative. The amount of land consumed is related to the miles of freeways, arterials, and rapid transit facilities constructed. A oompaku. of Fig. 17 with Pigs. 7,B and 9 shows that the amount of land &hen is atfected to a greaterdegreebpthemilesoffkeewayandsurface arterials construeted than ‘by the miles of rapid transit COllSttUCtGd.

Fatalities.The number of annual fatalities would irtornase under all Bve al&native transportation programs (Pig. E8):The High Transit Alternative would produce the

largest increase in fatalities (79%) and the High Highway Alternative would produce the smallest increase (35%). There would be, however, only small differences in the increase of fatalities among the 1990 Plans, Mode S@it, and High Highway Alternatives. ‘lk ntnnber of fatalities is related to split of travel between highways and transit, and between higher and lower level facilities and the amount of transit service. As the proportion of travel on transit increases, fatalities would deerease. Andastbe proportion of travel on freeways and rapid transit facilities increase (as opposed to surface arterial and conventional bus), fatalities would also decrease. And, as the vehicle miles of transit service increase, so drould the

E. WEINER

172 ALTERNATIVE TRANSPORTATION PROGRAMS 1880 PLANS

MODE SPLll

HIGH HIGHWAY

HIGH TRANSIT

EQUAL SPLIT

II

Ii

-800

-7W

-M)o

IIll

II -500

-400

-300

a0

II -100

0

+,W

II

+2W

+3W

+4W

1

II +SW

+SW

+7W

+8W

LAND CONSUMED (SD. MI.) 1972.90

Fig. 17. Change in square mile; of land consumed for alternative transportation programs, 197240.

ALTERNATIVE TRANSPORTATION PROGRAMS 1990 PLANS

MODE SPLIT

I

HIGH HIGHWAY

I

HIGH TRANSIT

I

EDUAL SPLIT

I

I

I

I

I

I

I

I

-80

-70

-80

-50

-40

-30

-20

.lO

0

I

I

+10

+20

I t30

I

I

I

I

+40

+50

t80

+70

I .80

PERCENT CHANGE 1972-W NOTE 1972 ANNUAL FATALITIES = 12,080

Fig. 18. Percent change in annual fatalities for alternative transportation programs, 1972-W number of fatalities. The combined effects are re5ected in the change shown in Fig. 18. Air pollution emission. Figures D-21 show the

percent changes in the daily tons of three types of air po~utank-carbon monoxide (CO), hydrocarbons (HC) and oxides of nitrogen (NO,). Air pollution emissions would decrease substantially under all alternatives, primarily because of lower polluting vehicles in 1990than in 1972. The difference in air pollution emissions among the funding mixes would be small areawide. The CO and HC emission levels would have the greatest decrease under the High Highway Alternative. This decrease is the result of higher speeds and less starting, stopping and

accelerating that would occur on the highway system when more money is invested in highways. Conversely, the High.Tmnsit.-Alternative would have the largest increase in.COand HC emission levels. This is because this alternative would not divert highway trips in sullicient numbers to poqpensate for the added congestion due to the overall .g&vth in highway travel. The results for NOX emission levels would be the reverse of those for CO and HC. This would occur because higher NOX emissions are produced at higher automobile speeds. It should be remembered that transportation is only one contributor to air pollution. A more sophisticated analysis

Assessing national urban transportation policy alternatives

H’GH H’GHWAY I HIGH

TRANSIT

EQUAL SPL’T /

0

-10

-20

-30

-30

PERCENT

-50

-60

-70

CHANGE

1972-90 NOTE

1972

DAILY

TON

OF CO = 48.300

Fig. 19. Percent change in daily tons of carbon monoxide (CO) for alternative transportation programs, 1972-90.

MODE SPLIT

EDUAL SPLIT

I

1

1

r,

,

0

-10

-20

-30

-40

PERCENT

-50

-60

-70

-80

CHANGE

1972-90 NOTE

1972 DAILY TONS OF HC=8,600

Fig. 20. Percent change in daily tons of hydrocarbons (HC) for alternative transportation programs, 197240.

MODE

SPLIT

HIGH

HIGHWAY

-10

,

-20

-30

-40

-50

-So

-70

PERCENT CHANGE 1972-90 NOTE

1972

DAILY

TONS

would be required to show the effect on overall air quality. The results displayed here show only the general decreases in air pollutant emissions with respect to alternative transportation programs. Gasoline Consumption. Figure 22 shows the percent changes in the gallons of automobile gasoline consumed daily that would result from the alternative transportation programs. For these analyses, the gasoline consumption rate was held constant from 1972 to 1990. Gasoline consumption would increase under all the programs, although the ditTerences among the programs would be small. The differences among alternatives appear to be related to the change in modal split (see Fig. 13). The three alternatives for which the transit’s proportion of travel market would increase, the 1990 Plans, High Transit and Equal Split Alternatives, would have about 2% less gasoline consumed than the two alternatives for which the modal split decreases. Although these differences are small percentage-wise, they represent a significant amount of gasoline that could be saved. Summary. In summary, major shifts in capital funds from highways to transit for the 1972-90 period for the Nation’s largest urbanized areas would improve transit trip times but would degrade highway trip times about the same amount. Highway speeds, however, would remain at 1972 levels or in some instances improve. These changes in trip times would cause large increases in transit trips and modest increases in transit’s share of the travel market. Negative social and environmental impacts in terms of dislocations and land consumed would be smallest relative to the other program alternatives that were analyzed. Fatalities would be greatest for the higher transit programs. Air pollution impacts would differ little among alternatives and showed mixed results. Automobile gasoline consumption would increase least in the High Transit Alternative; however, differences among alternatives would be small. Alternative level of total investment

::::r: 1E 0

173

OF NC+7,lSO

Fig. 21. Percent change in daily tons of nitrogen oxides (NO,) for alternative transportation programs, 1972-90.

To assess the effects of a lower level of investment on the 1990Plans, an alternative was analyzed for which the annual level of capital expenditures was reduced. This would result in an expenditure level of $129 billion, in constant l!Rl dollars, from 1972to 1990,which would be 20% lower than the $160 billion level in the 1990 Plans. The proportion of funds between highways and transit for the lower funding alternative was the same as that in the 1990 Plans Alternative. Effects of reduced investment. As can be seen in Fig. 23, the Reduced Investment Alternative would yield a reduction in the miles of highways from 5 to about 11% and, in rapid transit of almost 20% over the 1990 Plans Alternative. However, with respect to 1972, miles of freeways, surface arterials and rapid transit would increase 122.6, 45.2 and 265.2%. In regard to system performance, highway peak trip times would not change and transit peak trip times would increase relative to the 1990 Plans Alternative. Daily highway speeds would decrease less than 2%. Relative to 1972 conditions, highway speeds and transit peak trip

E. WEINER

174 ALTERNATlVE TRANSPORTATION PROGRAMS

lee0 PLANS

MOOE SPLIT

HIGH HIGHWAY

HIGH TRANSIT

EWAL

I

SPLIT

I

I

I

I

I

-50

40

-30

-20

-10

0

I

I

I

I

+10

+20

+r)

+40

PERCENT CHANGE 1972.90 NOTE 1972 GALLONS OF GASOLINE CONSUMED

DAILY = 9&4CC,WO

Fig. 22. Changesin gallonsof automobilegasolineconsumeddailyfor alternativetransportation programs,1972-90.

EFFECT FREEWAY MILES SURFACE fZEZ’AL RAPID TRANSIT LINE MILES AVERAGE DAILY HIGHWAY SPEEDS iE&lh%? TIMES PEAK-HOUR TRANSIT TRIP TIMES DAILY !&%” DAILY XSIT NiA

RESIDENTIAL DISLOCATIONS $

BUSINESS DISLOCATIONS LAND CONSUMED (SQ MILESI

N/A

TOTAL FATALITIES

I

TONS OFCO TONS OF HC TONS OF NOK GASOLINE CONSUMED I -70

-so

I 40

I 40

I

I,

40

.30

I

-20

LEGEND

-10

rIIIII 0

t10

I

+20

xi0

440

450

*BQ

I

+70

PERCENT CHANGE CHANGE FROM 1972

!!!f!? N/A

CHANGE FRDM 19BO PLANS - NOT APPLICABLE

EFFECT

Fig. 23. Effectsof 1972-90reducedinvestmentalternativecomparedto 1972base conditionsand 1990plans.

I +w

Assessingnationalurbantransportationpolicyalternatives times would each improve over 10%. Highway trip times would degrade about 4%. The modal split and number of transit trips would change less than 1% from the 1990 Plans Alternative, but would increase relative to 1972.The Reduced Investment Alternative would consume less land and cause fewer dislocations than the 1990Plans Alternative as a result of less construction of highways and rapid transit. Fatalities would change less than 1% compared to the 1990 Plans Alternative but increase 42.5% over 1972. Air pollution emissions would remain essentially unchanged relative to the 1990Alternative but would be substantially reduced from 1972 levels. Gasoline consumption would not change compared to the 1990 Plans Alternative but would increase more than 50% over 1972 conditions. Summary. Reducing the 1972-1990 investment by 20% in the 64 largest urbanized areas would change highway speeds, and transit and highway traveltimes less than 3%. As a consequence the modal split would change less than 1%. Dislocations and land consumed would decrease. But fatilities, air pollution emissions and gasoline consumed would remain relatively unchanged. Compared to 1972 conditions, this lower investment alternative, would still result in substantial improvements in highways speed and transit trip times.

173

are considering their use (U.S. Department of Transportation, 1974). The potential impacts of five peak-hour pricing policies on the 1990 Plans Alternative were analyzed. These pricing policies were as follows: (i) Doubling peak-hour parking rates; (ii) Halving peak-hour parking rates; (iii) Doubling peak-hour transit fares; (iv) Halving peak-hour transit fares; (v) Doubling peak-hour parking rates and halving peak-hour transit fares. The level of funding for the 1990Plans Alternative was used for each of the five pricing strategies. Funds were allocated among the four transportation modes-rapid transit, conventional bus, surface arterials, and freeways according to the 1990 Plans Alternative as outlined previously. Changes in the transit fares and parking rates are relative to those reported by the States and urban areas in the 1974 National Transportation Study. The effects reported here are compared in relation to the 1990 Plans Alternative, not in relation to 1972 conditions. Efects of pricing policies. Figure 24 displays the percent changes in peak-hour transit trips for the five pricing schemes. A doubling of parking rates would increase peak-hour transit trips by 8%. If the peak-hour parking rates are halved, transit tripes would decrease by 3.8%. A doubling of peak-hour transit fares would decrease peak-hour transit trips by almost 22%. If the fares are reduced by half, the transit trip would increase by 16.3%. Under the combined program of doubling parking costs and halving transit fares, in the peak-hour transit trips in the peak-hours would increase by almost 24%. As can be seen, the effects of transit fare changes on transit trips would be greater than equal percentage changes in parking rates. The effect of the various pricing schemes on daily travel demand can be seen in Fig. 25. As expected, the effect on

Alternative peak-hour parking rates and transit fares There has been growing interest in the use of peak-hour pricing schemes as means of altering travel patterns and to increase the efficiency of existing transportation systems. Various proposals have been advanced that are directed at reducing peak-hour automobile commuter travel and diverting automobile users to transit. To date, few urban areas have attempted parking surcharges or peak-hour transit fare reductions. However, many more ALTERNATIVE PRICING POLICIES

2 X PARKING

I

1/2X PARKING

2 X FARES

P

I I

l/2X

I

FARES

2 X PARKING ANC 1/2X FARES

a

-16

-10

-6

0

+5

+10

+16

PERCENT CHANGE FROM lSS0 PLANS NOTE 19SO PEAK-HOUR TRANSIT TRIPS = 21.100,MK)

Fig. 24. Changesin peak-hourtransittrips for alternativepricingpoliciesfor 1990plans.

+20

+25

E. WEINER

176 ALTERNATIVE PRICING POLICIES

2 X PARKING

1/2X PARKING

I

2 X FARES

1/2X FARES

2XPARKlNGAND l/2X FARES

-20

.15

-10

0

-5

+5

+10

+20

+15

+25

PERCENT CHANGE FROM 1990 PLANS NOTE 1990 DAILY TRANSIT TRIPS = 26.700,OW

Fig. 25. Changesin daily transit trips for alternativepricingpoliciesfor 1990plans. the daily modal split and number of transit trips would be smaller than the effects during the peak. The various pricing strategies would also have some effect on peak and offpeak automobile as well as transit trip times. The magnitude of the change was so slight, however (2% or less) as to be negligible. Summary. The analysis of alternative pricing policies indicates that changes in peak-hour transit fares would have a greater effect on transit use than equal percentage changes in peak-hour parking rates. The effect of halving transit fares would increase daily transit trips almost 13% over the 1990 Plans Alternative, which would be a 78% increase over 1972 conditions. This increase in transit trips would not occur without a potentially substantial cost to subsidize these fare reductions, which must be covered from other revenue sources. A possible approach would be to combine the transit-fare reduction with a parking-rate increase. This strategy would have the advantages of further increasing transit use and of providing some of the revenue to subsidize the lower transit fares.

Efect of changes in peak automobile occupancy. Figure 26 displays the percent change in daily modal split and daily automobile trip times for the two automobile accupancy alternatives. When peak auto occupancy is increased by XI%, daily mode split would decrease by 24.2%. When auto occupancy is doubled, mode split would decrease 30.3%. The decrease in transit use results from transit users shifting to automobiles. This shift is the result of improved automobile trip times as the number of automobiles on the highways decreases when peak occupancy rates increase. The improvements in automobile trip times can be seen in Fig. 25. When auto occupancy is increased by XI%, daily automobile trip times would improve by 5.4%. When auto occupancy doubles, trip times would improve by 1.3%.

DAILY

MODAL

DAILY

AUTOMOBILE TIMES

PEAK MODAL

Alternative peak automobile occupancy rates

Another type of alternative that would improve the efficiency of existing transportation systems and also reduce energy consumption is an increase in automobile occupancy rates. The effects of two alternative peak automobile occupancy rates were analyzed-(i) Peak automobile occupancy rates increased by 50%; (ii) Peak automobile occupancy rates increased by 100%. These alternative occupancy rates were applied to the automobile occupancy levels submitted by the States and urbanized areas in the 1990 Plans. These average 1990 automobile occupancy rates for the 64 largest urbanized were 1.2 for the peak period and 1.6 for the offpeak period.

1990 PLANS BASE CONDITION

EFFECT

GASOLINE

TRIP

18.9 MIN

SPLIT

PEAK AUTOMOBILE TIMES PEAK TRANSIT

7.9%

SPLIT

TRIP

17.7% TRIP

20.9 MIN

TlMES

31.9 MIN 1485 MILLION GALLONS

CONSUMPTION

-4O-3Om20-10 PERCENT LEGEND E ~_i

CHANGE

0 +10+20+30 FROM

1990 PLANS

PEAK AUTOMOBILE OCCUPANCY INCREASED BY 50 PERCENT PEAK AUTOMOBILE OCCUPANCY INCREASED BY 100 PERCENT

Fig. 26. Selected effects of increased peak automobile occupancy by 50and loo% on 1990plans.

Assessingnationalurbantransportation policyalternatives

The effect of increased automobile occupancy rates would be more pronounced during peak hours. Peak-hour modal split would decrease 31.5 and 40.4%, respectively, for the 50 and 100% increases in automobile occupancy rates compared to the 1990 Plans. Automobile trip times also would show greater improvements during peak hours-6.9 and 9.3% for the two automobile occupancy alternatives, respectively. Transit trip times, both peak and offpeak, would also be improved slightly by increases in automobile occupancy. These improvements would be 1.2 and 2.0%, respectively, for the respective increases in automobile occupancy. These improvements are due to improved bus speeds as the total number of automobiles on the highways is reduced. Increases in automobile occupancy rates would produce reductions in daily gasoline consumption. A 6.9% reduction would result from a 50% increase in occupancy. If automobile occupancy is doubled, daily gasoline consumption would decrease 10.9%. Reductions of this magnitude could significantly reduce the pressure on gasoline reserves. Summary.Although it seems unlikely that a doubling in peak automobile occupancy rates could be achieved, the analysis does indicate the upper bound of the potential effects that could result. Increases in peak automobile occupancy rates of 50 and .lOO%could reduce gasoline consumption 6.9 and 10.9%. These reductions could significantly ease current and future gasoline shortfalls. Wowever, occupancy increases could sufficiently reduce automobile congestion to cause a significant number of transit users to divert to automobiles. CONCLUSIONS

The purpose of the multimodal version of the TRANSUrban model system is to afIord an insight, at the national level policy planning scale, into the consequences of alternative policies and programs. The model is capable of treating the two principal modes of urban transportation, transit and highways, with transit characterized in terms of conventional bus and rapid transit, and highways in terms of freeways and surface arterials. The efficiency of the model system lies not in its application to any unique, individual urban situation, but rather in its ability to treat urban regions simulteneously in assessing national program alternatives. Experience with the 1972 and 1974 National Transportation Studies has demonstrated the useful role which such policy planning tools can play. While they may not be an adequate substitute for collecting detailed information from local levels of government concerning future transportation plans and needs, it is clear that detailed “field oriented” studies are extremely limited in terms of (1) the degree of local effort which can be expected in support of a national policy planning effort, and (2) the number of future transportation alternatives which can be considered by each jurisdiction. The National Transportation Studies conducted by the Department of Transportation have shown that what the field studies lack in terms of breadth of alternatives and speed of analyses can be provided by national level policy planning tools such TRANS-Urban. The TRANS effort

177

was not intended, nor was it used, to supplant the local inputs from States and urban areas, which could only have come from some form of field study. The role of TRANS-type procedures then becomes one of examining the implications of a much widei radge of alternatives (some of them perhaps extreme) and analyzing effects of changing assumptions and projections, in order to broaden the perspective of transportatior@icy planning beyond what might otherwise have been possible. It should be stressed that the macro-level analyses typified by the TRANS approach can in no way substitute for the more detailed planning tools which support specific plans and project level recommendations. The TRANS approach arose from the recognition that the level of analytical effort must be commensurate with the magnitude, level of aggregation, and complexity of the problem to be tackled. TRANS-Urban is a technique which can respond to the need for a wide range of planning information for transportation resource allocation.

Acknowledgements-The author acknowledges the invaluable contributionsof Anthonv R. Kane and Stes/art N. McKeown of the Federal Highway ,&inistration, Oflice of Program and Policy Planning,WilliamL. Noack of the Officeof the Secretary, Officeof TransportationPlanningAnalysis and WilliamFlii of ControlData Corporation.The work reportedin this paperwould not have been possible without their assistance..

REFERENCES Bellomo SalvatoreJ., TurnerChristopherG. and JohnstonDenis K. (1972) A mode choice model for relating demand to investment.Highway ResearchBoard Record Number 392. CreiPhtonHamburg.Inc. (1971)Freeway-SurfaceArterial VMT S&ter. Prepare; for the U.S. Deparimeniof Transportation, FederalHighway Administration. GendellDavid S. (1973)An applicationof the TRANSapproachto evaluatingnationaltransportationalternatives.Proceedingsof fhe International Conference on TransportationResearch. Bruges, Belgium. GendellDavid S., HillegassThomasJ. and Kassoff Harold(1973) Effects of varying policies and assumptions on’ national highway requirements. Highway Research Board Record Number 458.

Hill Donald M., TittermoreLarry and Gendell David S. (1973) Analysisof urbanareatravelby timeof day. Highway Research Record Number 412.

Kassoff Harold and Gendell David S. (1971) An approach to multiregionalurban transportationpolicy planning. Highway ResearchBoard Record Number 348. Mongini Anigo (1972) Relation of National transportation planningand State transportationplanning.Highway Research Board Record Number 401. PeyrebruneHenry L. (1974)The use of the NationalTransportation Studyprocessby stateand local governments.Presentedat the Fifteenth Annual Meetingof the TransportationResearch Forum. SwerdloffCarlN. (1972)The 1972NationalTransportationStudy; The processand results. Compendium o/Papers Fromthe 42nd Annual Meeting. Instituteof TrafficEngineers. Swerdloff Carl N. and Mongini Arrigo (1974 The National TransportationStudy:Its u&at the FederalGovernmentlevel. Proc. 15th Ann. Meeting-Transportation Research Forum, Vol. XV, Number 1. _ U.S. Departmentof Transportation(1970)1970National Highway Needs Report.

U.S. Departmentof Transportation(1971)National Transporta-

178

E.

WEINRR

tion Planning Manual (1970-1990); Manual A: General Instructions. U.S.. Department of Transportation (1972a) 1972 National Highway Needs Report. U.S. Department of Transportation (1972b) 1972 National Transportation Report. U.S. Department of Transportatiou (1974)1974National I’kansportation Report; Summary. Weiner Edward (1971)A Guide to the 1972National Transportation Needs Study. Oflice pf Systems Analysis and Information, U.S.Department of Transportation. Weiher Edward, Kassoff Harold and Gendell David S. (1973)

Multimodal national urban transportation policy planning

model. HighwayResearch Board Record Number 458. Weiner Edward (1973)The TBANS Urban model system and its application in the 1972National Tmnsportation Study. Proceed ings of the International Conference on Transportation Research. Bruges, Belgium. Weiner Edward (1974a) The national requirements for urban public transportation funds, Transportation Research Board, Record 519. Weiner Edward (1974b) Urban Issues In the 1974 National Transportation Study. Presented at the ASCEIEICIRTACJoint Transportation Engineering Meeting, Montreal, Canada.