METHODOLOGY

AREA LICENSING SCHEME - SINGAPORE

OVERVIEW
EFFECT ON ROAD USE
EFFECT ON EMISSIONS
POLITICAL SUPPORT OR RESISTANCE
COST
REVENUE
TECHNICAL IMPLEMENTATION
MISCELLANEOUS
SUMMARY

VARIABLE-TOLL EXPRESS LANE FACILITY - ORANGE COUNTY, CALIFORNIA

OVERVIEW
COSTS
EFFECT ON ROAD USE
POLITICAL SUPPORT OR RESISTANCE
TECHNICAL IMPLEMENTATION
SUMMARY
FUTURE RESEARCH

WORKS CITED

BIBLIOGRAPHY

APPENDIX 1 - EMISSIONS BEFORE AND AFTER IMPLEMENTING THE ALS 18

Methodology

In order to conduct a thorough case study analysis, we have identified 6 criteria with which we will evaluate relevant case studies.  The following table lists the 6 criteria and the issues to be addressed under each of the criteria.

Table 1: Evaluation Criteria for Case Study Analysis
 

Criteria Issues	To Be Addressed
Effect on Road Use	Effect on congestion.  Effect on modal split.  Number of users.
Effect on Emissions	Effect on air quality with an emphasis on greenhouse emissions.
Political Support   or Resistance	Income group equity - effect on different income group brackets.  Gender/Age equity - effect on different sexes and age brackets.  Geographic equity - locational effects.  Public acceptance.
Cost	Capital costs.  Operating costs.  Revenues generated.
Revenue	How revenues from the program are spent.  The success of the programs towards which the generated revenue is spent.
Technical Implementation	Technology compatibility.  Enforcement.  Privacy.  Price determination.

 

At this stage of our research, we are compiling information for our analysis by organizing the material according to the defined evaluation criteria.   For our April report, we intend to have additional case study material as well as an analysis of the material.  The analysis will entail the strengths and weaknesses of the various case studies in the context of what potentially, would work best for the City of Toronto.

Included in this report is the data collected to date pertaining to Singapore’s Area Licensing Scheme and Orange County, California’s Variable-Toll Express Lane Facility.  Following the data is a brief summary of each case study and a list of future research plans.
 
Area Licensing Scheme - Singapore

OVERVIEW

Singapore is an island with a total land area of 648 square kilometres and in 1991, had a population of 3.4 million (Phang & Toh, 1997:97).  More than three quarters of the population lives in self contained towns that are connected via a network of highways (Menon et al, 1993:44).  Since the early 1960’s, Singapore’s economy has grown, on average, 8 per cent per year.  Singapore’s per capita gross national product in 1995 was S$34,500 or approximately US$24,500 (S$1 = US$0.71) (Phang & Toh, 1997:97).

The manually operated, cordon road pricing system implemented in Singapore, the Area Licensing Scheme (ALS), was the first of its kind.  It was implemented within the Central Business District (CBD) in June of 1975.  The original purpose of the program was to discourage commuters from relying on automobiles.  Since then, the program’s objective has been revised.  As of June 1989, the purpose of the ALS is to serve as a traffic management tool to curtail congestion (Menon et al, 1993:44).

Table 2: The Original ALS (1975-1989) and the Revised ALS (1989-Present) (Menon et al, 1993:45)
 

	Original ALS	Revised ALS
Objective	Manage the widespread use of private cars	Congestion pricing
Restricted Zone (Area)	610 ha in 1975; increased to 710 ha after 1986v	725 ha
Restricted Hours	7:30 - 10:15 a.m.	7:30 - 10:15 a.m.   4:30 - 6:30 p.m
Restricted Vehicles	Private car, company car and taxi	Private car, company car, taxi, goods vehicle, non-scheduled bus and motorcycle
Daily ALS Fees	S$2 for taxi; S$5 for private car; and S$10 for company car, that is, cars owned by companies for business purposes	S$3 for car, taxi, goods vehicle and non-scheduled bus; S$1 for motorcycle; and S$6 for company car

 
There are four components to Singapore’s ALS (Menon et al, 1993:44):

• Restricted Zone - This area encloses the most congested parts of the city.
• Restricted Hours - Times during which area licenses must be purchased and displayed on automobile windshields in order to enter the restricted zone.
•  Restricted Vehicles - There are various categories of restricted vehicles to whom the restricted hours are applicable.
• Area License Fees - These licenses must be purchased and they vary in shape and colour depending on vehicle type and the month of the year.

 Effect on Congestion:

• Morning inbound private car volumes decreased by 73 per cent under the initial implementation of the ALS (Menon et al, 1993:45).  Under the revised ALS, inbound private car volumes increased by 10.2 per cent (because of the fee reduction from S$5 to S$3) in the morning, and decreased by 56 per cent in the evening (Menon et al, 1993:46).

•  Morning inbound taxi volumes decreased by 64 per cent under the original scheme (Menon et al, 1993:45).  Under the revised ALS, evening inbound taxi volumes also decreased by 54 per cent (Menon et al, 1993:46).
•  Inbound motorcycle volumes were largely unaffected (Menon et al, 1993:45).
•  The volume of inbound goods vehicles (who were not subjected to the original ALS) increased by more than 100 per cent after its initial implementation (Menon et al, 1993:45).  Once the ALS was revised and goods vehicles were subjected to the same fee as private cars, the volume of inbound goods vehicles decreased by 51 per cent in the morning and by 60 per cent in the evening (Menon et al, 1993:46).
•  The implementation of the evening restricted hours has increased travel speed by 7 kmh within the restricted zone (Menon et al, 1993:46).
•  Average traffic speeds increased by 22 per cent within the restricted zone (Chin, 1996:793).
• In June 1995, Singapore introduced a Road Pricing Scheme (RPS) on the East Coast Parkway.  Table 3 compares inbound traffic volumes between May 1993 (pre-All-Day ALS) and May 1994 (post-All-Day ALS):
•  Criticism: the ALS fee is too high as it has resulted in a 45 per cent decrease in traffic volumes - the goal was to reduce traffic volumes by 25 to 30 per cent.
•  Those who switched from (single occupancy vehicles) to carpools experienced, on average, a saving of 9 minutes per trip (Chin, 1996:797).

•   Between 1975 and 1989, total vehicle population increased by 77 per cent.  But, the total inbound traffic during the restricted hours is less than 70 per cent of what it was in 1975, before the ALS (Menon et al, 1993:45).

•  Work related transit trips increased from 33 per cent before the ALS to 69 per cent in 1983 (Menon et al, 1993:46). OR/ from 33 per cent before the ALS to 46 per cent after implementation (Chin, 1996:793).
•  The number of vehicles entering the restricted zone fell by more than 45 per cent (Chin, 1996:793).
•  Public transport users experienced significant reductions in travel time (Chin, 1996:797) (Phang & Toh, 1997:101).
•  Hitchhiking became more popular as people would pick up hitchhikers as a way of getting around the ALS (Menon et al, 1993:46).

• The automobile is responsible for about 65 per cent of air pollution in Singapore (Chin, 1996: 787).  However, the effect of the ALS on emissions is very difficult to isolate.  Appendix I graphically shows the levels of various pollutants over time (before and during the implementation of the ALS).  Nitrogen oxides decreased, while reduction in carbon monoxide and smoke levels were marginal (Chin, 1996:795).  In general, air pollution has decreased since the implementation of the ALS.  This however, cannot be solely attributed to the ALS.  Some regulatory controls in addition to the ALS, that inevitably have affected the amount of air pollution include (Chin, 1996:788):
•  Since July 1992, a more stringent standard for exhaust emissions has been implemented.
•  In January 1991, unleaded petrol was introduced as well as a new pricing system that made unleaded petrol $0.10 cheaper than regular petrol.
•  Since July 1992, all new cars fitted with catalytic converters must also be fitted with a fuel tank restricter so as to accept the smaller unleaded petrol dispensers.
•  Since October 1992, all motorcycles and scooters have to comply with a more stringent standard for exhaust emissions.
•  Since August 1989, the emission standard for all diesel vehicles decreased from 55 Hartridge Smoke Units (HSU) to 50 HSU.

• Between 1975 and 1989, employment in the restricted zone grew by 30 per cent (Menon et al, 1993:45) (Chin, 1996:795).
• Traffic on roads surrounding the restricted zone generally increased (Menon et al, 1993:47) (Chin, 1996:793) (Phang & Toh, 1997:101).

•  Motorists reported large improvements in travel speed and travel time in the restricted zone during the restricted hours (Chin, 1996:793).
• Pedestrians felt less at risk of being hit by an automobile (Chin, 1996:793).
•  A public opinion survey indicated that people generally perceived a reduction in noise and an increase in safety when crossing roads (Chin, 1996:793).
•  The public tends to view road pricing as a necessary nuisance and grudgingly accept it (Menon et al, 1993:48).

•  The original ALS incurred a capital cost of S$6.6 million in 1975 dollars and a monthly operating cost of about S$59,000 in the first 10 years (Menon et al, 1993:47).
•  The revised ALS incurred a capital cost of S$170,000 and average monthly operating costs of about S$295,000 (Menon et al, 1993:47).
•  In 1992, the annual revenue from license sales was S$38 million.  The annual revenue from collecting fines was S$3.85 million (Menon et al, 1993:47).
•  The revenues generated by the ALS is 11 per cent of the annual money being spent on road and related facilities (Menon et al, 1993:47).
• The initial costs of the scheme (setting up of gentry posts, construction of fringe car parks, network effects of diverted traffic and the enforcement costs) have been outweighed by the benefits (Chin, 1996:797).
•  The revenue alone from the scheme is sufficient to offset the costs (Chin, 1996:797).

• Singapore’s Park & Ride Scheme failed because people did not find the public transit system attractive.   They viewed it as less desirable than carpooling because it was, in essence, a two-mode trip (Chin, 1996: 794).
•  Carpooling was a success.  By November 1978, it accounted for 53 per cent of all car trips - 3 times as much as it did in July 1975).

•  Singapore’s experience indicated that the ALS is easy to set up and does not require heavy investments in infrastructure, but its operation is labour intensive as it is manually enforced.
•  Compliance is manually enforced by the police stationed at each of the entry points recording the license plates of vehicles without valid licenses (Phang & Toh, 1997:98).
•  To reduce the incentive to bunch-up travel during unrestricted or cheaper hours, emphasis should be place on the appropriate timing and shoulder-pricing of tolls (Phang & Toh, 1997:100).
•  Manual enforcement can be very complicated.  Singapore has 16 different types of licenses (Whole-Day ALS, Part-Day ALS, RPS, and daily and monthly licenses for three categories of restricted vehicles).  Some inherent limitations of the manual enforcement method include: drivers must figure out which license to buy, enforcers must identify the licenses without drivers slowing down at entry points (as they are not required to) and the problem of people illegally switching licenses between vehicles (Phang & Toh, 1997:101).
• The ALS and RPS systems are very labour intensive - they require more than 120 people to manage them (Phang & Toh, 1997:101).

• The success of the program cannot be attributed solely to the ALS.  There were complimentary measures introduced to ensure that the desired outcomes were realized. Some measures that complimented/enhanced the ALS include: increased motor vehicles taxation, staggered working hours, road construction programs,  higher parking fees, construction of fringe car parks to encourage park and ride schemes and pick-up points were set up to encourage car pooling (Chin, 1996:793).
•  Evening traffic rush-hour was less congested than many other cities.  Singapore averaged 25 km/h (or 19 km/h according to Phang & Toh, 1997:97) during evening rush hour before the implementation of the ALS.  This is quite favourable compared to a 10 - 13 km/h evening rush hour peak in cities like Bangkok and New York (Chin, 1996:795).
•  Congestion pricing has been criticized for resulting in the spreading of traffic too thinly over available road space.  Environmental considerations might require its concentration on a limited number of roads (Chin, 1996:797).
•  To successfully implement congestion pricing, there must be
•  an appropriate social political framework, i.e. a culture of compliance.
•  supportive measures such as continuous and comprehensive land use planning integrated with investment and planning for infrastructure (Chin, 1996:798).
•  The ALS is easily comprehensible and relatively cheap to enforce and operate (Chin, 1996:798).
•  The ALS worked in Singapore because it was complemented with: legislative and fiscal measures, careful land use planning, reorganization of and investment in efficient public transport system, investments in road infrastructure, traffic management measures and efficient enforcement.
•  People were willing to pay upwards of US$70,000 for the right to own a car for 10 years (Phang & Toh, 1997:98).

The ALS was successful in decreasing congestion, perhaps even too much as it exceeded its goal of reducing traffic volumes by 15 per cent.  The ALS significantly decreased the number of cars entering the restricted zone and the use of transit services increased.  Both transit users and automobile drivers experienced reductions in travel time.  The ALS did not have negative impacts on businesses or employment levels within the area, but traffic on surrounding roads increased.  There was no severe public opposition to the Scheme and the public experienced noticeable benefits.  Although the direct impacts of the ALS on emissions are difficult to isolate, air quality has generally improved since the implementation of the ALS.  The Singapore experience suggests that it is very useful to invest revenues in carpooling infrastructure, as carpooling gained significant popularity after the implementation of the ALS.  There were no major technical hurdles in implementing or operating the ALS, but it is extremely labour intensive to operate.  All in all, the ALS has been successful in achieving its goals.
 

Variable-Toll Express Lane Facility - Orange County, California

OVERVIEW

The State Route 91 (SR 91) Variable-Toll Express Lanes, located in Orange County, California, is the first fully automated, privately owned, toll road in the world (I).  The four-lane toll facility began operating on December 27, 1995.  The 10 mile long toll lanes were built adjacent to a public freeway.  The primary goal of the program is to manage congestion in the area.  The average one way trip time for SR 91 commuters is over an hour (Applied Research...II:4).  Toll rates vary by time of day, depending on the traffic of the adjacent freeway.  The tolls range from US$0.25 at night to US$2.50 in the peak hours.  Vehicles with three or more occupants ride free.

COSTS

•  The first year’s toll revenues covered operating costs but only a small portion of amortized capital costs (Applied Research…II:1).

Effect on Congestion:

• After 6 months of implementation, the average time for a PM peak trip declined from 30-40 minutes to less than 10 minutes per trip (Applied Research...II:3).
•  After a year and a half of implementation, the average time for a PM peak trip had increased from the previously recorded 10 minutes to 12-13 minutes per trip (Applied Research...II:3).

•  Even though the number of vehicles on SR91 increased, public transportation patronage also grew, suggesting that people were not discouraged from using public transport in favour of the toll routes (Applied Research...II:2).

•  The Route 149 express bus in the SR 91 corridor did not experience a decline or increase in ridership.  In addition, there is no evidence that traffic changes influenced the bus operation in any way (Applied Research...II:7).
•  Within 3 months after the SR 91 toll lanes opened, the amount of HOVs (high occupancy vehicles with 3 or more occupants) during peak periods increased by 40 per cent on all lanes of the freeway (toll and free lanes) (Applied Research...II:4).
•  The number of SOVs also increased by just under 40 per cent.  This increase does not consider the increase of SOVs as a result of the previously established growth trend for SOVs, nor the number of SOVs returning to SR 91 from parallel routes (Applied Research...II:4).
•  The number of HOVs with 2 occupants increased slightly once the toll routes were operating (Applied Research...II:5).
•  Even though the number of HOVs increased, the large increase of SOVs on the road caused a small, but statistically significant downward trend in average vehicle occupancy (Applied Research...II:5).
•  The number of people who switched from HOVs to SOVs (25 per cent) exceeded those that switched from SOVs to HOVs (7 per cent) (Applied Research...II:5).
• HOVs are more likely to use the toll lanes than SOVs (Applied Research...II:5).

•  As a result of the increased capacity of SR 91due to the opening of the toll lanes, average daily weekday traffic increased by 14% - this translates to an increase of about 28,000 vehicles per day.  This increase is not however, entirely new drivers.  For example, it is estimated that 21 per cent of the increase is from travelers who had previously been using less congested routes than the SR91.
•  In spring 1997, the percentage of SR 91 travelers who used the toll lanes ranged from about 7 per cent in the mid-day off peak, when time savings were minimal, to a high of 35 percent during the peak hour when delay to freeway users was an estimated 12-13 minutes.  This suggests that SR 91 commuters value their time at US$13-14 per hour (Applied Research...II:3).
•  Approximately 50 per cent of the people who regularly travel SR 91 never use the toll lanes (Applied Research...II:3).

Income Equity:

• Higher income groups are more than twice as likely to be frequent users of the toll lanes.  But, 50 per cent of the highest income travelers (> US$100,000 annual household income) said that they never or infrequently use the toll roads while 25 per cent of the lowest income travelers (< US$25,000 annual  household income) said that they use the toll roads frequently (Applied Research...II:6).
•  Of the 20 per cent of commuters who adjusted their mode of travel, more than 90 per cent of the lowest income group (< US$40,000 annual household income) switched to HOVs, while other income groups experienced a shift of about 60 - 70 per cent (Applied Research...II:6).

• The youngest and oldest travelers are less likely to frequently use the toll lanes (Applied Research...II:6).

• A small travel time improvement of about 6 minutes per trip was observed on one of the parallel roadways (Applied Research...II:3).
•  Traffic volumes remained generally stable in the SR 57/60 freeway corridor located roughly parallel to SR 91 (Applied Research...II:4).
•  63 per cent of companies contacted (within the area of SR 91) said that the toll lanes are good for local business.  They said that their workers, customers and suppliers experienced improved ease and reliability of travel (Applied Research...II:8).

• Of the 50 per cent of regular users of SR 91, more than half indicated that the amount of congestion experienced was not worth the cost of the toll, 20 per cent said their trip patterns were not conveniently served by the toll lanes and 10 per cent did not approve of the facility altogether.
•  60 - 80 per cent of SR 91 commuters supported the idea of introducing tolled roads to mitigate congestion.  The approval percentages for actual toll lane users were 5 - 10 per cent higher than for non-users, with little variation among the different vehicle occupancy categories (Applied Research...II:7).
•  After a year of implementation, the percent of commuters supporting the use of congestion pricing increased from 45 % to in between the 60 - 75 per cent range (Applied Research...II:7).
•  A study conducted in spring of 1997 indicated that 50 - 60 per cent of SR 91 commuters supported the idea of switching from a predetermined toll schedule to one that reflects current traffic condition, with an established maximum (Applied Research...II:7).
•  Commuters surveyed, both before and after implementation of the toll roads, demonstrated much support for other technical and institutional features of the express lanes, including exclusive AVI toll collection, photo-enforcement, and toll discounts for HOVs with 3 or more occupants.  40 - 50 per cent of the commuters surveyed supported the idea of having a special toll discount for low income commuters (Applied Research...II:8).
•  Only 72 per cent of business survey respondents expressed approval of electronic toll enforcement, compared to almost 90 per cent of commuters (Applied Research...II:8).
•  Some people chose to use the toll lanes even when the time savings were clearly less than the tolls paid.  Two reasons cited for this are added driving comfort and the perception of greater safety (Applied Research...II:3).

•  All tolls are collected by Automatic Vehicle Identification (AVI).
• The electronic toll-collection technology used on SR 91 is inter-operable with other publicly operated toll roads in Orange County (Applied Research...:1)
•  Proper use of the automated toll lanes is enforced by the California Highway Patrol (CHP), under contract to the California Private Transportation Company (CPTC), and through the use of video surveillance equipment (Applied Research...:1).

People are using the SR 91 toll lanes and the numbers are expected to continue increasing.  Despite the increase in the number of vehicles on SR 91, transit usage was not negatively impacted by the toll routes.  Both the number of HOVs and SOVs increased.  The overall effect however, was a decline in average vehicle occupancy.  The SR 91 toll lanes have been successful in decreasing congestion along SR 91 and do not appear to have had any negative impacts on local traffic or businesses.  Higher income travelers are most likely to use the toll roads and the youngest and oldest travelers are least likely to travel the toll routes.  There has been no major opposition to the toll routes and support is continuing to rise.  To date, there is very little information regarding the cost of the program and no information regarding the impact of the program on air quality and how the generated revenues are spent.

Future Research 

•  There are various congestion pricing projects that are currently being explored in the United States (Hattum & Zimmerman, 1996:5):

From these nine pilot projects, only two (Orange County and Minneapolis) are in their implementation phase.  Many of the others however, have conducted feasibility studies.   Obtaining these studies is an obvious next step in conducting our case study analysis.

•  Toronto’s 407 electronic toll route is another case study that has obvious important implications for our analysis of the feasibility and desirability of congestion pricing for the City of Toronto.
• There are also European examples of congestion pricing that will be considered, specifically initiatives taking place in Sweden and Norway.

•  In addition to congestion relief tolling concepts, there are also congestion relief parking fees that will be considered.  The following table outlines the types of congestion relief parking fees we plan to consider and relevant case studies (adapted from Hattum & Zimmerman, 1996:5):

 Works Cited

1. Applied Research & Development Facilities & Activities, California Polytechnic State University Foundation. “Information on the SR91 Toll Lanes”. www.ardfa.calpoly.edu/~jwhanson/sr91info/sr91info.html.
 
2. Applied Research & Development Facilities & Activities, California Polytechnic State University Foundation II. 1998.  “Evaluating the Impacts of the SR 91 Variable-Toll Express Lane Facility, Final Report”. http://ceenve.calpoly.edu/sullivan/sr91/sr91.htm.
 
3. Chin, A. T. H. 1996. “Containing Air Pollution and Traffic Congestion: Transport Policy and the Environment in Singapore”. In Atmospheric Environment. Vol. 30, No. 5, pp. 787 - 801.
 
4. Hattum, D. V. and M. Zimmerman. 1996. Buying Time: Guidebook, A Guidebook for Those Considering Congestion Relief Tolls in Their Communities. www.hhh.umn.edu/Centers/SLP/Conpric/guidebk.htm.
 
5. Menon A. P. et al, 1993. “Singapore’s Road Pricing System: Its Past, Present and Future”.  In ITE Journal. Vol. 63, No. 12. pp. 44 - 48.
 
6. Phang S. Y. & R. Toh, 1997.  “From Manual to Electronic Road Congestion Pricing: The Singapore Experience and Experiment”. In Transportation Research. Vol. 33, No. 2. pp. 97 - 106.
  

1. Applied Research & Development Facilities & Activities, California Polytechnic State University Foundation. “Information on the SR91 Toll Lanes”. www.ardfa.calpoly.edu/~jwhanson/sr91info/sr91info.html.
 
2. Applied Research & Development Facilities & Activities, California Polytechnic State University Foundation II. 1998.  “Evaluating the Impacts of the SR 91 Variable-Toll Express Lane Facility, Final Report”. http://ceenve.calpoly.edu/sullivan/sr91/sr91.htm.
 
3. Arrillaga, B. 1993. “U.S. Experience with Congestion Pricing”. In ITE Journal. Vol. 63, No. 12, pp..39 - 43.
 
4. Atash, F. 1996. “Reorienting Metropolitan Land Use and Transportation Policies in the USA”. In Land Use Policy. Vol. 13, No. 1. pp. 37 - 49.
 
5. Bhatt, K. 1993. “Implementing Congestion Pricing: Winners and Losers”. In ITE Journal. Vol. 63, No. 12, pp. 33 - 37.
 
6. Chin, A. T. H. 1996. “Containing Air Pollution and Traffic Congestion: Transport Policy and the Environment in Singapore”. In Atmospheric Environment. Vol. 30, No. 5, pp. 787 - 801.
 
7. Cloke, J. and R. E. Layfield. 1996. “The Environmental Impact of Traffic Management Schemes”. In Urban Transport & the Environment II.
 
8. Decorla-Souza, P. 1993. “Congestion Pricing: Issues and Opportunities”. In ITE Journal. Vol. 63, No. 12, pp. 27 - 32.
 
9. Environmental Defence Fund. 1996. EDF Letter. Vol. XXVII, No. 6.
 
10. Hattum, D. V. and M. Zimmerman. 1996. Buying Time: Guidebook, A Guidebook for Those Considering Congestion Relief Tolls in Their Communities. www.hhh.umn.edu/Centers/SLP/Conpric/guidebk.htm.
 
11. Helali, K. and B. G. Hutchinson. 1995. “The Potential Effects of Road Pricing on Air Quality in the Toronto Area”. In Urban Transport & the Environment II.
 
12. Johansen, F. 1989. “Toll Road Characteristics and Toll Road Experience in Selected South East Asia Countries”. In Transportation Research. Vol. 23A, No. 6, pp. 463 - 466.
 
13. Lampe, A. J. 1993. “Effects of Road Access Pricing at the Los Angeles Airport: A Case Study”. In ITE Journal. Vol. 63, No. 12, pp. 22 - 24.
 
14. Langmyhr, T. 1997. “Managing Equity: The Case of Road Pricing”. In Transport Policy. Vol. 4. No. 1. pp 25 - 39.
 
15. Lave, C. 1994. “The Demand Curve Under Road Pricing and The Problem of Political Feasibility”. In Transportation Research. Vol. 28A, No. 2, pp. 83 - 91.
 
16. May, A. 1993. “International Experiences with Congestion Pricing”. In ITE Journal. Vol. 63, No. 12, pp. 14 - 20.
 
17. McCarthy, P. S. 1996. “The Effect of Congestion Pricing on Metropolitan Demands for Fuel Efficient Vehicles”. In Urban Transport and the Environment II.
 
18. Menon A. P. et al, 1993. “Singapore’s Road Pricing System: Its Past, Present and Future”.  In ITE Journal. Vol. 63, No. 12. pp. 44 - 48.
 
19. Minnesota Department of Transportation and Mn/DOT Office of Alternative Transportation Financing. Minnesota Congestion Pricing Study. www.hhh.umn.edu/Centers/SLP/Conpric/mndot.htm.
 
20. Munnich, L. W. et al. 1995. Institutional and Political Issues in Congestion Pricing: New Models for Federal, State and Local Cooperation in Infrastructure Investment.  University of Minnesota, Hubert H. Humphrey Institute of Public Affairs: pp. 2 - 20.
 
21. Odani, M & N. Akita. 1996. “Public Attitudes Towards the Introduction of Road Pricing in the Central Business District”. In Urban Transport & the Environment II.
 
22. Phang S. Y. & R. Toh, 1997.  “From Manual to Electronic Road Congestion Pricing: The Singapore Experience and Experiment”. In Transportation Research. Vol. 33, No. 2. pp. 97 - 106.
 
23. Stough, R. R. & P. Rietveld, 1997. “Institutional Issues in Transport Systems”. In Journal of Transport Geography. Vol. 5, No. 3. Pp. 207 - 214.
 
24. Transportation Action Network. 1996. Progress. www.transact.org/nov96/sr91.htm.
 
25. Department of Transportation Federal Highway Administration and Hubert H. Humphrey Institute of Public Affairs. 1996. Regional Congestion Pricing Workshop: Proceedings. www.hhh.umn.edu/Centers/SLP/Conpric/chicago.htm.
 
 
 

Appendix 1 - Emissions Before and After Implementing the ALS