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Road Pricing Context

OBJECTIVES

SCHEME DESIGN

TECHNOLOGY

BUSINESS SYSTEMS

Prediction

PREDICTION

TRAFFIC EFFECTS

ENVIRONMENT

ECONOMY

EQUITY

Appraisal

APPRAISAL

Decision Making

ACCEPTABILITY

TRANSFERABILITY

Implementation and Evaluation

EVALUATION

IMPLEMENTATION

Case Studies

Bergen

Bologna

Bristol

Cambridge

Durham

Dutch National Case

Edinburgh

London

Manchester

Milan

Nord-Jaeren

Oslo

Rome

Stockholm

The Hague

Trondheim



Urban Road User Charging Online Knowledge Base

What Have Been The Effects Of Ruc On Traffic Levels?

Durham implemented a congestion charge for entering and utilising Sadler Street which is the cul-de-sac road that provides access to Durham’s historic cathedral area. Santos (2004) and Wafer (2007) both report that traffic on that road fell by up to 85% from pre charging situations. The Durham case study may be considered the closest example to the textbook model of road user charging since its operation reflected the requirement of levying a charge for traversing a particular stretch of road as advocated by Walters (1964). No other impacts have been reported and there is little further analysis of this scheme in the available literature.

CUPID (2004) reported that the traffic flows in Trondheim dropped between 5-7% when a road pricing package was introduced. However we must bear in mind that the objective of the Norwegian schemes was primarily to raise revenue rather than to control car usage and therefore large reductions in traffic were not sought. This thus underlies the importance of defining carefully the scheme objectives as mentioned in Chapter 2.

Other real world examples of road pricing are more complex as they are expected to have significant traffic impacts on the traffic network. The inter play of network effects is an important consideration in the overall evaluation of the scheme benefits.
Schemes examined

We attempt to draw insights from the three following implemented schemes.

• Singapore originally implemented an area licence charge (known as the Area License Scheme (ALS)) to enter the Central Business District in July 1975. Initially vehicles were required to pay a fee to enter this Restricted Zone between the hours of 0730 -0930 (Monday to Friday). In August 1975, this was extended to end at 1015. Since its initial implementation the scheme has undergone a variety of changes and modifications. In this chapter, we look at the immediate short run impacts of the traffic flows on vehicles as it gives an important picture of the possibilities of changes in the traffic flow patterns of employing such a traffic restraint policy using information from Holland and Watson (1978). In 1998, Singapore subsequently revised the technology of the pricing system from a manual license to an all electronic tolling system to charge per entry into the Central Business District as well as other key arterials, with all day time varying charges. This latter scheme is known as the Electronic Road Pricing (ERP) Scheme. The Singapore case study is interesting because we can consider the impacts on traffic flows due to a change in the scheme operation to an electronic tolling system in 1998 which charges for an individual trip as opposed to the previous flat fee per vehicle regardless of number of times of entry. This is the current operating scheme in Singapore and information can be found in Menon (2000).
• London implemented a congestion charge of £5 in February 2003 to enter and drive a vehicle within the area of Central London bounded by the Inner Ring Road. The charge was raised to £8 in July 2005 and the area extended in February 2007 to include the Western Extension. The background of the London Congestion Charging Scheme (LCCS) and details of its operation can be found in Deliverable D3 as well as many published papers in the literature (e.g. Santos, 2004, Santos and Fraser, 2006) and various TfL reports (TfL (2003-2008). TfL (2003) also gives detailed traffic reports and analysis of the pre-implementation situation. It is important to point out that several changes have taken place in London simultaneous with the implementation of the congestion charge. This include the development of a major junction within the charging zone as well as the renewal of the Victorian pipe system, both measures are likely to have serious impacts on travel time and congestion within the charging area. External factors such as the general background traffic decline in London as noted by TfL (2003) can also exaggerate the impact of the congestion charge. In addition, there were other extraneous influences (namely the threat of terrorism and an underground derailment) that occurred during the operation of the scheme.
• The Stockholm trial ran from 3rd January to July 31 2006. During this period charges were levied on vehicles for entering the city of Stockholm and these charges varied by time of day ranging from SEK 10 to SEK 20 (approximately €1.10 to €2.20) with a maximum charge per day of SEK60 (€6.60). (Further details of the scheme and the exemptions may be found in Deliverable D3 as well as Eliasson et al (2009) and Stockholmsförsöket (2006a,b)). While the scheme is now permanent with minor variations to the design, there is limited information available on the current permanent scheme at the time of writing. Just as in London, there was a variety of external factors that makes it difficult to easily separate out the effects of the scheme from other external impacts. For example it is pointed out in Eliasson et al (2009) that there was an accident on an important bridge link which would cloud the picture of the “before scenario”. In addition, about the same time as the trial was in place, there was a fuel price increase in Stockholm which could have had an impact on reducing vehicular traffic.

Bearing the above caveats in mind, we report on the changes in traffic flow, changes in time of day effects as well as changes in delay/speed achieved for each of these pricing schemes examined.
Changes in Traffic Flow

Singapore

Table 7 1 shows the changes in the number of vehicles entering the Restricted Zone comparing the immediate short run impact of the scheme.

The following facts are evident:

• Cars entering before charging hours commence rose by 24%
• There is a large reduction (over 47%) in number of vehicles entering the zone due to the charge. This masks the actual reduction in cars entering (75%) vis-à-vis pre charge levels (Watson and Holland, 1978)
• When the scheme operated till 0930, there was an increase in the number of vehicles entering the zone after charging hours. This prompted an extension of the operation hours to 1015 which effectively resolved this problem.
 

Table 71 All Vehicles Entering the Restricted Zone

 

 

Time

 

 

March 1975

 

 

July 1975

 

 

Sep  1975

 

 

 

 

 

 

 

 

Before ALS

 

 

ALS in effect from  0730 – 0930

 

 

ALS in effect from 0730 – 1015

 

 

Half Hour Before Restricted Hours

0700 – 0730

9,800

11,510 (17%)

11 073 (13%)

Restricted Hours

 

0730 – 0930

 

55,313

29, 532 (-47%)

  -

 

74,014

 

-

41,198 (- 73%)

Half Hour After Restricted Hours

 

 

0930 – 1000

 

12,775

 

14,041(+10%)

 - 

1015 – 1045

-

-

13,925

Source: Watson and Holland (1978) Table 4.1 p. 41


When the initial scheme was implemented, it was enforced by visual inspection. In 1975, labour costs in Singapore were relatively low and this enforcement method was not costly. One of the exemptions was that cars entering the zone carrying four or more passengers were exempted from paying the charge. Table 7 2 shows the number of car pools (defined by the authorities as passenger cars with four or more occupants) entering the Restricted Zone. This exemption led to a surge in the number of car pools entering the zone during the operation hours of the scheme.

Table 72 Carpools Entering the Restricted Zone

 

 

Time

 

 

March 1975

 

 

July 1975

 

 

Sep  1975

 

 

 

 

 

 

 

 

Before ALS

 

 

ALS in effect from 0730 – 0930

 

 

ALS in effect from 0730 – 1015

 

 

Half Hour Before Restricted Hours

 

 

0700 – 0730

 

 

687

 

 

672 (-2%)

 

 

702 (+2%)

 

 

Restricted Hours

 

 

0730 – 0930

 

 

 

 

2,341

 

 

3581 (+53%)

 

 

  -

 

 

 

 

 

 

 

 

4083

 

 

4217

 

 

Half Hour After Restricted Hours

 

 

0930 – 1000

 

 

258

 

 

332 (+29%)

 

 

 - 

 

 

1015 – 1045

 

 

-

 

 

-

 

 

352

 

 

Source: Watson and Holland (1978) Table 4.12 p. 57



While it is clear that there is a significant reduction in traffic, detractors in the literature (e.g. Toh,1977; Wilson (1988); McCarthy and Tay (1993)) have all pointed out that the charge might have been set too high and as a result there has been over restraint and therefore an under-utilisation of road space.

When Singapore switched over contiguously to the ERP scheme in 1998, Menon (2000) reported that there was a significant reduction in the number of vehicles entering the charge zone vis-à-vis pre ERP with figures in the range of 15% (for the entire day) and 16% (for the morning peak period). In other words, fine tuning the charges with the ERP system continued to manifest reductions of traffic in a system which originally had a licensing scheme (albeit at a fixed fee) in place.

TRAFFIC ON BYPASS ROUTE

There exists a bypass route around the periphery of the charging zone which carries traffic bound for the charging zone as well as orbital traffic. There is evidence to suggest that the speeds fell with ERP. However the most likely reason for this is that drivers would reroute onto this bypass to avoid having to pay the charge if bypassing the zone. Consequently with increased traffic flows, there is a consequent reduction in travel speeds as shown in Table 7 3.

Table 73 Traffic Circulating on

Bypass Route

AM Peak: 0800-0900

Direction

 

Traffic Flow

 

(Pre ERP) vehicles/hour

 

Traffic Flow

 

(Post ERP)

 

Vehicles/hr

 

Speeds (pre ERP) kph

 

Speeds (post ERP) kph

 

East/West

 

3060

 

3440 (12.4%)

 

23

 

16

 

West/East

 

1905

 

2081 (9.2%)

 

26

 

21

 

PM Peak:1700-1800

 

East/West

 

2028

 

2644 (30.4%)

 

26

 

24

 

West/East

 

2654

 

2466 (-7.1%)

 

23

 

24

 

Source: Menon (2000) Table 1 p. 42

 


London

TRAFFIC ENTERING THE ZONE

Total traffic entering the charging zone of the LCCS (see Table 7 4) fell by 14%, in line with forecasts, but the actual reduction in cars entering the zone was much larger (33%). The reduction in cars entering was offset by increases in buses (as part of a planned strategy to allow for mode shift) as well as taxis, motorcycles and cycles, which are exempt from the charge.

Table 74 Traffic Entering Central London Charging Zone

2003 vs 2002

2007 vs 2002

All vehicles

-14%

-16%

Four or more wheels

-18%

-21%

Cars

-33%

-36%

Vans

-11%

-13%

Lorries

-10%

-5%

Licensed Taxis

17%

7%

Buses and Coaches

23%

31%

Powered Two Wheelers

13%

-3%

Pedal Cycles

20%

66%

Source: Table 3.1 p. 41 TfL(2008)


The longer run impacts (comparing 2007 vs 2002) are also important since there may be a time lag for traffic to adjust to the changed conditions produced by charging. While it is clear that the reduction in the number of cars entering the zone has stabilised at around 36%, the initial increase in powered two wheelers reported in 2003 has subsequently been reduced to less than the pre-charging numbers in 2002. However there is a sustained increase in the number of pedal cycles (albeit from a low base) and this trend seems to be increasing. In addition when the fee was raised from £5 to £8 in July 2005, TfL surmises that there was only a relatively “indistinct aggregate traffic volume response” in terms of traffic flows entering in the congestion charging zone (TfL, 2007 p.19).


TRAFFIC ON THE INNER RING ROAD

The inner ring road forms the boundary of the congestion charging zone and as passage through it is not subject to payment of the charge, it serves as the most likely diversionary route for through traffic avoiding the zone. TfL (2004) indicated that in the short run there was a 4% increase in vehicle kms travelled for all vehicles on the inner ring road. However, the longer term picture presented in TfL (2008) suggests instead a decline in traffic on the inner ring road back to pre-charging levels. This remains the situation despite changes to the scheme (including the Western Extension).

TRAFFIC ON RADIALS APPROACHING THE CORDON

It is expected that reductions in traffic entering the charging zone should be reflected also in traffic approaching the radial roads inbound and outbound to the zone. Table 7 5 shows the year on year percentage changes in vehicular traffic (4 wheels or more) inbound and outbound observed on the radials. A key figure was the reduction of 5% in traffic in 2003 which has been followed by a year on year reduction of approximately 1%. If the 2006 data was considered to be an anomaly (TfL 2008 p. 50) and can be disregarded, the traffic data is broadly in line with the general recognised background decline in traffic volumes in London that was occurring before the congestion charge (TfL 2008 p. 50).

Table 75 Traffic Inbound/Outbound on Radial Approaches to Cordon

Year

2003

2004

2005

2006

2007

% change year on year in vehicles (4 or more wheels)

Inbound/outbound

-5 /-5

-1 / -1

-2/-1

-7/-12

+3/+3

Source: TfL(various years)


Stockholm

During the Stockholm trial, vehicles entering and exiting the city of Stockholm (by passing one of the 18 control points or gantries) were liable to pay a toll as mentioned previously.

TRAFFIC ENTERING/EXITING THE ZONE

Table 7 6 shows the changes in traffic flows comparing the pre-charging scenario (Spring 2005) vis-à-vis the post-charging scenario (Spring 2006). We distinguish the changes by time period as the toll paid varies by time of day.

Table 76 Changes in Traffic in Congestion Charging Zone Comparing Spring 2006 (post charging) with Spring 2005 (pre charging)        

Locale

Morning Peak

 

(0700-0900)

Evening Peak

 

(1600-1800)

Charge Period

 

(0630-1830)

Full 24 hours

Congestion Charging Zone (Entering/Exiting)

-16%

-24%

-22%

-19%

Major Inner City Streets

-7%

-10%

-10%

-7%

Minor Inner City Streets

-8%

-13%

-10%

-8%

Source: Stockholmsförsöket(2006b), Table 1, p. 13

The recorded 22% reduction during the charge period shown in line 1, column 3 of Table 7 6 pertains to an aggregation of changes in traffic entering/exiting the congestion charging zone over the 18 control points. At the individual level, traffic passing through (in both directions) the congestion charging control points fell by between 9% (4,000 vehicles) and 26% (9,000 vehicles) during this same period. The smallest reduction of 9% was recorded on the control point leading to/from Lindingö island and this is primarily attributable to the exemption for traffic to and from Lindingö which crossed the charging zone within 30 minutes. On the other hand the largest recorded decrease of 26% was attributable to drivers diverted onto a parallel bypass corridor instead of travelling through the charging zone.

Traffic on the major and minor inner city streets was not reduced by as large an extent as traffic entering. This does not seem surprising since traffic circulating entirely within the congestion charging zone is not required to pay the toll (Eliasson et al 2009).

TRAFFIC ON RADIALS APPROACHING THE CORDON, OUTER LINK ROADS AND OUTER-CITY ROADS

Table 7 7shows changes in traffic on the radial roads approaching the cordon and the outer link roads and the outer city roads. Comparing Table 7 6 with Table 7 7, the reduction in traffic on the outer approach roads is much less than the reduction achieved within the charging zone.

Table 77 Changes in Traffic for Radials and Outer Approach Roads Comparing Spring 2006 (post charging) with Spring 2005 (pre charging)     

Locale

Morning Peak

 

(0700-0900)

 

Evening Peak

 

(1600-1800)

 

Charge Period

 (0630-1830)

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Full 24 hours

Outer approach roads

 

-3%

-4%

-5%

-5%

Outer link roads

4%

4%

 

1%

 

0%

 

Outer city roads

-5%

-4%

-5%

-5%

Source: Stockholmsförsöket(2006b), Table 1, p. 13

 

Since the changes for the outer link roads and the outer city roads are all aggregated changes, they mask the within group variations. It is noted in Stockholmsförsöket (2006b, p. 14) that there are “relatively large variations between different roads”. These roads could potentially be diversionary routes but the evidence suggests that this is not the case and that autonomous traffic increases (background traffic growth) could have easily masked the impact of the congestion charge.

Prior to the implementation of the congestion charge, there were fears that the toll free Essinge bypass, which was close to capacity, would be overwhelmed by traffic (Eliasson et al 2009). Similar fears were noted for the newly constructed Southern Link. The reality was that while there was some increase on the Essinge bypass, it was difficult to determine whether this was the effect of the congestion charging or of autonomous traffic increases. On the Southern Link, there was a noticeable increase but this seems to have been explained by autonomous traffic increases (Eliasson et al (2009)). Another argument cited by Stockholmsförsöket (2006b, p. 14) related to the possibility of congestion charging enabling increased throughput by reducing delays.

Due to the multitude of conflicting factors, as well as an accident on a critical bridge link during the period prior to the trial (hence reducing recorded pre-charging traffic), it is very difficult to determine the “pure” effect of congestion charging on changes in the overall traffic flow patterns on these roads further outside the cordon.

Due to the exemption allowed for alternative fueled vehicles, there has been a substantial increase in the number of such vehicles registered in Stockholm since the scheme became a permanent feature. However, without any further information on modal splits, it is very difficult to study the impacts of the scheme on modal splits by vehicles entering the congestion charge zone.

Time of Day Impacts
Another important traffic impact to be considered is the changes in traffic flows during periods of non-charging.

Singapore

In the ALS implemented in 1975, there was no charge during the evening peak for entering the Restricted Zone. The initial argument against an evening peak charge was that if commuters did not drive in, they would not have vehicles to drive back home in. However the evidence from Singapore did not tie up with this hypothesis. In fact whilst the evidence suggested that the reduction in traffic flows in the morning peak was 47% (see Table 7 1), the equivalent reduction in the evening peak was only 6%. In fact Watson and Holland (1978) remarked that “it was puzzling the level of evening traffic, which must have included a large flow of home bound commuters, was apparently not affected by measures that that induced many commuters not to drive into the Restricted Zone during the morning restricted hours” (Watson and Holland, 1978, p. 59).

When Singapore introduced the ERP to replace the ALS system, Menon (2000) reports that there was an increase in traffic entering the congestion charging zone (10.6% compared to pre-ERP) half an hour prior to the start of the operation hours of the scheme. This is similar to the phenomenon already observed in Table 7 1 under the ALS.

Menon (2000) also highlighted the fact that traffic volumes increased and speeds dropped marginally up to 45 minutes after the end of operation. This substantiates the hypothesis of increased peak spreading due to the ERP.

Stockholm

Evidence gathered during the Stockholm trial (Stockholmforsoket(2007b)) indicated that traffic volume reductions varied during the day. This was in line with the idea of charge differentiation as practised in Singapore’s current scheme.

Differentiation of charges in Stockholm (charges were twice as high in the peak as compared to the off-peak periods) showed that the relative volume reductions (see Table 7 6) turned out to be slightly lower during the (morning) peak than during the average charging period. This could be explained by the fact that commuters who were working in the city of Stockholm were of higher income and would rather pay the charge than to switch their modes.

There was a small but statistically significant reduction in traffic post charging hours which accords with the hypothesis that if cars were not driven into the zone during the day, cars would not be driven back during the evenings. This contradicts the results reported earlier for Singapore’s ALS scheme as highlighted by Watson and Holland (1978).

The Stockholm results showed that the time-of-day effects were much smaller than anticipated. While the authorities expected to see peak spreading on a much larger scale due to the differentiated charges, the available data did not substantiate this hypothesis. Instead the data showed that there were no time periods during which traffic over the cordon increased to avoid other time periods when charges were higher.

Changes in Speed/Delays

Another important consideration in the assessment of traffic restraint policies is the extent by which the URUC can improve travel speeds. As pointed out in TfL (2003) the objective of the LCCS was not to reduce traffic volumes per se but to reduce congestion. Therefore it is important to consider what has happened to congestion within and outside the zone in order to understand the overall picture.

Singapore

Based on a combination of moving car observation surveys, panel data and simulated assumptions, Watson and Holland found the following results as shown in Table 7 8.

Table 78 Traffic Speeds (km/h) with and without ALS 

 

 

 

 

 

 

 

 

Without ALS

With ALS

 

Percentage Change

 

Inside Restricted Zone

27

33

22%

Inbound Radials into Zone

29

32

10%

Outbound Radials from Zone

35

35

0

Ring Road

25

20

-20%


While improvements in speeds within the restricted zone as well as on the inbound radials due to the restrictions, traffic diversion to the Ring Road led to reductions in speeds there. This evidence underlies the importance of considering wider network impacts of a URUC scheme on periphery and alternative routes.

When the ERP system was introduced, Menon (2000) explained that the ability to vary the charges quarterly was useful because this meant that once the traffic speeds dropped below a certain target level (which was found through empirical speed flow relationships to be in the range of 20 to 30 km/h), a revision in the rates could be triggered and rates adjusted upwards so as to price traffic off the roads and maintain speeds at the target level. Conversely, if traffic speeds rose beyond 30 km/h, the trigger mechanism would be activated to reduce the charges to maintain the optimal speeds.

London

Table 7 4 and Table 7 5 have shown that traffic flows entering London have been reduced. However, there is less information reported in London on speeds. TfL instead uses a measure of excess time taken to travel 1 kilometre in the period under consideration vis-à-vis travel during free flow conditions as a measure of congestion (TfL 2003). Hence the measure relates to the excess travel time taken due to the impacts of stop-go traffic conditions and stationary traffic but will also include some delays due to traffic signal operations (which might vary from period to period depending on signal timing plans implemented).

CONGESTION IN THE CHARGING ZONE

Table 7 9 shows the average excess delays used to capture the impacts of the charge on travel conditions within the zone.

Table 79 Average Excess Delays (minutes per km) in Charging zone

Time Period

Before Charging

After Charging

AM Shoulder (0600 – 0700)

1.0

0.5

AM Peak (0700 – 1000)

2.3

1.5

AM interpeak (1000-1300)

2.5

1.7

PM interpeak (1300-1600)

2.5

1.6

PM peak (1600-1830)

2.5

1.6

PM shoulder (1830 – 2000)

2.2

1.5

Source: TfL (2005) Figure 4 p.16


Table 7 9 highlights an interesting feature in that the peak congestion occurs during the period 1000-1300. In addition, while we would reasonably expect to see traffic adjust to enter the charging zone in the time period just before the start of charging hours (0700 hrs), it seems that the greatest reduction is achieved during this period with a 50% decrease instead.

Unfortunately, longer run data publicly available is not distinguished by time periods and it is therefore difficult to obtain a clear picture of congestion in the zone. Thus Table 7 10 only reflects the mean excess delay during charging hours within the charging zone. Despite the short term (2003 and 2004) reductions in excess travel rates, this measure suggests that the explicit objective of reducing congestion within the charging zone has not been fulfilled in the longer term. This table clearly shows that the excess delay in 2007 is no different from that in 2002 (pre-charging). TfL (2004) recognises what it terms the “accelerating loss of the original decongestion benefits”. Kearns (2008b) attributes this loss in decongestion partly to explicit measures by TfL to reduce capacity of the network for environmental purposes (e.g. around Trafalgar Square), and partly to losses in capacity from extraneous causes, including renewal of London’s water supply system and construction works at a major junction.


Table 710 Mean Excess Delay (min/km) during Charging Hours

 

 

 

 

 

 

 

 

 

Year

Mean Excess Delay (Mins/Km)

 

Percentage Change from 2002

 

2002

2.3

Base

2003

1.6

-30%

2004

1.6

-30%

2005

1.8

-22%

2006

2.1

-8%

2007

2.3

0%

Source: TfL (2008) Table 4.1 p. 57


CONGESTION ON THE INNER RING ROAD

TfL reported an excess delay on the inner ring road of 1.9 min/km as the reference value in 2002. As shown in Table 7 11, there was a significant reduction in excess delays during the period post charging in the short run. However this measure of congestion rose again in 2006 to exceed pre-charging levels and it is understood that this occurred for a variety of reasons including major road works at a key junction and renewal of underground water pipes in London, which are unrelated to the URUC scheme. It is therefore difficult to disentangle the pure effects of reductions in traffic due to the URUC scheme alone.

 

Table 711 Excess Delays (mins per km) on

Inner Ring Road

 

 

 

 

 

 

 

 

Year

2002

2003

2004

2005

2006

Excess Delays (minutes per km) over Free Flow Conditions

1.9

1.5 – 1.7

1.6 – 1.9

1.7-1.8

1.9 – 2.0

Source: TfL(various years)


Stockholm

The observations from the Stockholm trial indicate that there have been substantial reductions in delays due to congestion charging (Eliasson et al 2009; Stockholmsförsöket,2006b). In line with the reductions in traffic mentioned earlier, there has been a corresponding reduction in travel times. The maximum reduction occurred on arterial roads with travel times 50% of those in the spring of 2005 before charging began.

On the other hand there are areas in which the travel times have increased. In the first instance, traffic on the Essingeleden bypass experienced increases but these were not statistically significant when compared to the day to day road network variability (Stockholmsförsöket, 2006b). Another significant source of increase in journey times was on Södra Länken but the expert group report attributes this to the road already carrying traffic volumes far exceeding its original designed capacity (Stockholmsförsöket, 2006b).

No information on this theme is currently available from the case studies