Résultats exploitables
Increasing numbers of private cars in Rome have resulted in increased traffic congestion and atmospheric pollution. As a result the city has established various strategies to tackle traffic problems, including restricted access restriction for non-catalysed vehicles within the 'Rail Ring', a densely populated area surrounding the historic centre. Goods vehicles were exempted together with specific categories of vehicles and road users.
Analysis using the Ishtar suite was undertaken for two scenarios, the do nothing scenario and the actual scenario (based on the traffic measures described above). The Ishtar suite ran the simulated case study using its emission, dispersion, exposure and health effect modules. The emission and dispersion modules were used to model CO and PM10. CO was also modelled using the exposure module and PM10 by using the health effects module.
The study includes the 'Heaven' area which lies within the internal rail-ring, excluding the Rome ZTL (Limited Traffic zone), which covers part of the historical center. The area being studied is 16.35 square kilometres.
The Rome case study collected data on meteorological conditions, traffic data, fleet composition, population, emissions, concentration of pollutants, and evaluation of exposure and health effects.
Assessing exposure to a pollutant requires information on the pollutant concentration at a given location and the duration of contact with individuals or population groups. When the concentration of a pollutant to which a person is exposed can be measured or modelled, exposure is determined from concentration and time spent in contact with the pollutant.
When assessing the effects of a particular pollutant, in our case for ambient PM10 pollution, to an exposed population, there are two assumptions to be made: the concentration consists of the average measured in the city or area where the population lives, everyone is assumed to be exposed to the same average concentration. With this information it is possible to calculate the attributable risk as a proportion, while to obtain the absolute number of attributable cases it is necessary to know, in addition, the observed rates of disease or mortality occurrence in the population under study.
Conclusions
Two traffic scenarios were tested in an area of the municipality of Rome.
Pollutant concentrations data of a day, the 12th of November 2001, have been calculated for CO and PM10 within a semi-central area. Traffic data from O/D matrices were elaborated by software external to the Ishtar suite. A simulation of the Ishtar suite was operated through the use of several software parts of the suite, in particular, as no effect were expected in terms of traffic flows, the model for the simulation of citizen behaviour and traffic have not been used, and, as no effects are expected also in terms of noise and accident, the Suite Entry Point was the direct impacts model for the calculation of pollutant emissions. The data obtained for the testing area of Rome are not indicative, due to some exceptional parameters, but were suitable for a simulation in Ishtar. CO and PM10 were chosen and modelled, their emissions within the area under analysis have been modelled and used as input for the dispersion model. The PM10 dispersion modelling output was used to generate an exposure and health effects assessment. The simulation gave a negligible difference between the two scenarios in terms of health impacts of the tested policy. Synthetically, it has to be stressed that these results are a simulation of the behaviour of a population assumed as resident all year long in the investigated area and constantly exposed to an average level of pollution. The reality is much more complex and the results have to be carefully interpreted as a rough assessment of the real situation. The very low difference between the scenarios and between the scenarios and the background can be explained with the small dimensions of the area under analysis that is strongly affected by the surroundings, the pollutant sources that have not been modeled.
At the end of the simulation the Emission, Dispersion, Exposure and Health effects models within the Ishtar suite were used. The part of the Ishtar suite used in this simulated case study supports the possibility of analysing different scenarios and organises data in an integrated way.
This study recorded the situation that existed prior to the construction of Attica Road motorway and compared it with environmental (air quality and sound pollution), traffic and health conditions following the opening of the motorway.
The case study helped the actors involved to mitigate the impacts caused by the motorway, thereby improving its operation status.
Introduction
In Attica region, where Athens is one of the major municipalities (114 municipalities in total for the whole region), there are more than 2.000.000 vehicles running on the network and more than 5.500.000 person trips (all purposes) every day.
The total area of Attica was modelled using a GIS platform and was available for the Ishtar applications. In this model there were than 50.000 links (basic roadway network). The total area was divided into a number of traffic zones (700 to 1300 depending on the focus of the application) where data exist in databases for all the traffic zonal system.
The application used for the Ishtar suite case study, dealt with the new roadway construction the so-called 'Attica Road' or 'Attica Periphery Road'. This new toll highway was assessed in terms of traffic, toll strategy and pricing, environmental conditions on the highway and all of its entry points and exits.
In addition, all new projects that impact, one way or another on this new motorway were assessed as part of the total traffic condition in Attica region. The 2004 Athens Olympic Games, resulted in new projects being constructed (stadiums, accesses, roadway links, light rail, etc). All of these projects as well as the additional required infrastructure have been used in the database.
The application envisaged is two fold:
1. The largest domain (45 x 45 km2): to provide regional conditions (traffic, air quality, noise, etc.) where the results will be given by the current TRANSCAD Transport Model (with a resolution of 500m)
2. The smallest domain (5 x 5 km2 or less): to be assessed by the ISHTAR suite modules (at a street level, accesses, etc. district, area, etc).
The data used for implementing the project included:
Traffic data,
average vehicle flow measurements,
average vehicle speed measurements,
occupancy rates,
level of Service (HCM 2000 HCS 2),
numerous measurements of effectiveness.
Meteorological and air quality data
Meteorological data included wind direction, wind speed, standard deviation of wind speed, temperature, relative humidity, solar radiation, precipitation. In Attica region there are nine stations for calculating air pollution concentration.
Air Pollution
Air Pollution Analysis was undertaken using TEE 2003 model and LAKES Environmental Software with the Support of the Aria Impact Models
Noise Analysis
Noise Analysis has been undertaken with the SoundPlan Model
Traffic Analysis
Apsis Ltd., as mentioned above, primarily uses TRANSCAD as the basic tool for the implementation of the Transportation Model of Attica Region. This tool offers the possibility to reduce the modelling (study) area and create an OD-matrix for the sub area chosen.
Conclusions
Ishtar provided various benefits to:
- Ministry of Planning, Environment & Public Works, Attica Road JV, and overall
- the citizens of Athens (especially those living in areas adjacent to the highway) with the analytical structure of the models and the results, by explaining in clear manner the highway's operation and its impacts (before & after).
One major issue that has to be noted, is that with the operation of the highway, (after case study analysis), 250.000 vehicles travel in Attica Road at an average of 15 km per trip, meaning (250.000 veh x 15 km) 3.750.000 vehxkm daily. All of these vehicles are now in the highway, providing a major relief to the local network of 3.750.000 vehicles km daily.
In the cases where the noise caused by the traffic was proven to be above the limits for the surrounding settlements, noise barriers have been installed along the motorway, benefiting residential and other sensitive areas (schools, hospitals, etc.).
Analysis of air pollution and noise impacts indicated that the motorway would have a major negative impact on the environment. People previously opposed to such an enormous project were re-assured and since no great health impacts were about to be placed on their lives. The report also noted that accidents have been reduced in the Attica region.
The aims of the case study are the following:
??analyse pollution concentration records for the Brussels area,
??design crisis scenarios with different levels of severity, these scenarios include banning some categories of vehicles from driving in the Brussels region,
??forecast the behaviour of the travellers facing the different scenarios, through preliminary surveys,
??design accompanying measures: parking provision at the edge of the banned zone, increased public transport services,
??estimate traffic impacts calculated by mean of traffic models,
??estimate noise and pollution emissions in the Brussels area using the Ishtar suite of models, both with and without implementing the crisis scenarios.
The main objective was to test the feasibility and the efficiency of a Car Free Day (CFD) in Brussels. Car free days were supposed to be part of a global ozone plan for the Brussels Capital region. Since the beginning of the "In town without my car!" event, the Brussels Capital Region has been participating. As a result, on average, noise was reduced by ten decibels; while the highest level of NOx emissions recorded at the city's busiest traffic intersection was eight times lower than for a normal weekday. CFDS are an efficient way to reduce concentrations of NOx, CO and particles but are useless for decreasing ozone levels over the short-term.
Until now, despite their success, the CFDs were planned only on Sundays to limit impacts on economic activities. It is clear that, if a CFD had to take place a workday, some important accompanying measures would be necessary to avoid complaints. This report will review these particular measures and determine the real impacts of such actions in terms of road traffic volume and of emissions and concentrations of pollutants in the city. We will also compare measures regarding different factors such as measure implementation costs, environmental impacts or exposed population size.
If the conclusions of the study were positives, public authorities would be encouraged to practice CFD also during the week.
L%Study
In each scenario, there were exceptions to the prohibition on cars, including public transport, fire brigade, ambulance service, police force, electric or hybrid vehicles and LPG or natural gas vehicles.
To model the impact of the ban a survey was carried out on car and almost half of those canvassed (47%) consider these actions to be awkward or very awkward. However, it is important to note that nearly 30 % of the people do not perceive any inconvenience due to car banning policies. Before applying measures, it was necessary to determine suitable measures for limiting impacts on economic factors and facing the environmental crisis. The following aspects have been analysed:
??Definition of parking areas: crisis car parks were created in the most strategic locations, so that people could easily reach the city centre by public transport;
??Public transport crisis plan: a public transport plan specifically adapted to a much higher demand has been developed;
??Accompanying and monitoring measures: techniques making it possible to refuse infringing vehicles from accessing the Brussels-Capital Region as well as measures aimed at avoiding problems for residents of close to the Region (restrictions on travel, channelling of vehicles towards crisis car parks), were examined;
? The public must be informed about the measures adopted. Different forms of communication have been investigated, including television, radio, internet, etc.
Thanks to survey data analysis, it was possible to model the effects of their behaviour on the Brussels Network. It also allows fuel consumption to be expressed as in kilograms and as litres. Simulations were carried out to differentiate between the two main emission reduction factors, i.e.
1. reduction in vehicle numbers,
2. more environment-friendly vehicles.
Conclusions
??Each of the four scenarios showed a significant reduction in emissions;
??The Greenhouse Gas Emissions reduction (CO2) was only due to the traffic flow reduction, but not to fleet specificities. Fleet technical characteristics have however a favourable impact on the others pollutant emissions;
??The Diesel scenario has got a very significant impact in terms of PM10 emissions reduction.
The reduction, in comparison with the Reference scenario is about 80 %;
??The fleet evolution has at least as much impact as the traffic banishment in itself.
A tunnel was built to connect two major roads in order to reduce traffic congestion in residential areas. One of the tunnel's entrances was situated close to residential buildings, therefore, an environmental impact study was commissioned to show that the effects of this project were in accordance with noise pollution and air quality standards.
The Graz case study concerned a traffic calming measure for a residential district between two major roads in the north of the city of Graz. Due to the construction of a 600 m long tunnel the traffic - which was formerly directed through narrow streets within this residential district - can now bypass this area. Unfortunately one portal of the tunnel had to be situated in close vicinity to a housing area. To minimise the negative effects of the concentrated pollution exchange at the portal special measures have been implemented. These measures cover the erection of an up to 7 m high noise barrier and a special ventilation control at times with a high air pollution load.
The effect of this improvement of the road network on the traffic flow within the city of Graz is relatively small. Hence only a few km of the road network had to be considered and the study domain covers some 2 times 2 km only. Effects on air quality are remarkably only directly at curb side. Effects on noise are much bigger.
The measurement programme covered noise and air quality measurements before and after the opening of the tunnel. The noise measurements showed a remarkable reduction in noise levels in the residential areas 'as the traffic load could be reduced dramatically at that locations' but also alongside the main road which bears now much more traffic. This reduction is related to the noise barrier which was part of the project. The changes in air quality can not easily be allocated to the project as the before and after tunnel measurements did not cover the same time of the year. The after measurements benefited also from the improved dispersion conditions during the measurement time (spring time vs. late winter time). However, there is an indication that air quality improved at least in the residential areas, while it didn't grew worse alongside the east portal region of the tunnel, where much more traffic prevails due to the tunnel.
As the study domain (the effected area) is relatively small only modules of the Ishtar suite were applied. A full Ishtar suite application for such a small area and limited measure would not make any sense (e.g. there is no effect on monuments to be expected).
Within this study the following the following Ishtar tasks were performed:
-validation of the emission model TEE,
-validation of the dispersion tool ARIA Impact,
-application of TEE to the case study region,
-application of the dispersion tool ARIA impact to the case study region,
-comparison of the model results with other dispersion tools.
The general conclusion for the tested Ishtar suite modules is as following:
The emission module (TEE) delivers reliable emission rates for calculations in street networks. The fleet composition has to be adjusted manually for each country and base year.
The dispersion module ARIA Impact is designed for dispersion purposes in non-built up areas. It delivers reliable results for line sources. The model is not designed for special cases like tunnel portals and noise barriers.
The general conclusion for the Graz test case is as follows:
The measure was set in order to restrict traffic in a residential zone and divert it into a road tunnel. The positive effect of this measure was proven by noise and air quality measurements. Even in zones with a traffic increase an improvement in noise pollution could be achieved as noise barriers were included into the measure. The effect on air quality was also proven by application of dispersion models. The Ishtar dispersion module ARIA Impact was able to show the general trend. The trend on the small scale (portal regions) was confirmed by application of more detailed model.
The Grenoble case study, defined in 1999, concerned the impacts of measures for improving the traffic flow and supporting public transport. Hence, new traffic lights and reserved lanes for public transportation on very central boulevards were set in operation. The objective of these measures was:
??to test the possibility of reducing the number of lanes dedicated to car traffic (from 6 to 4),
??to improve the average speed of public transport,
??to reduce car speeds, and monitor the impact on traffic flow.
Within the Ishtar work the measure should have been assessed in terms of traffic, air pollution and noise. The objective of this Ishtar case study was to compare the results of the simulations done with the modules of the Ishtar suite to the measurements done before the project in 1999 and afterwards in 2000.
Collected data
Data was collated concerning the geographical, traffic, environmental (air quality and noise pollution), and meteorological situation. Traffic data was available for the roads Joseph Vallier and Marechal Foch. The measures taken led to a traffic reduction of some 10 %, accompanied by an average speed reduction in the same size. Unfortunately no information was collected in other parts of the adjacent road network.
Noise measurements were performed on two locations in April 1999 (before) and April 2000 (after the implementation).
An average reduction in noise level of about 1.5 dB(a) was recorded. The second monitoring location showed no difference between in the situation before any measures were taken. In order to check the influence on air quality a mobile monitoring station was installed in the eastern part of the domain. The western part is monitored by a permanent station. Unfortunately the monitoring in the eastern part lasted only for 14 days, which is too short a period to determine the influences due to changes in meteorological conditions. The station in the western part should give more reliable data. In order to see the influence of a general trend in air pollution between the two monitoring periods January to June 1999 and January to June 2000 data from a background station was used.
Ishtar modules used in the case study
The following tools were used to assess environmental impacts:
traffic nnumbers (manual input from DAVISUM results), GIS system SIG Geomedia transferred to ISHTAR-GIS,
emissions TEE2003 (ISHTAR module), not adjusted to the French fleet,
pollution dispersion ARIA Impact (ISHTAR module), noise (no measurements available).
Results
The implementation of the measure (reserved lanes and improved traffic lights) led overall to a small reduction in emissions (approx 3 % for CO, NOx and VOC). The effects on air quality have been calculated but could not be displayed due to software problems. However it can not be expected that the small changes in emissions in a restricted area will have a big impact on air quality. The monitoring programme concerned noise measurements at one locations and air quality at two locations. Referring to noise pollution a reduction of 2 dB(a) is reported for one part of the domain while in a second part no changes could be found. Referring to air quality a reduction of some 8 % in NOx and up to 40 % (!) in PM for short term and 2 % in long term were found. The short term (14 days) reduction was definitely biased by the different general meteorological conditions between the monitored period in 1999 and 2000. The long term values (6 months) are much more reliable.
Conclusion
The Grenoble case study concerned a measure which combined traffic management with an improvement in public transport. As the study domain (the effected area) is relatively small only modules of the Ishtar suite were applied. A full Ishtar suite application for such a small area and limited measure would not make any sense (e.g. there is no effect on monuments to be expected).
Within this study the following Ishtar modules were used:
??the full Ishtar interface as a module manager
??the ISHTAR GIS module
??the emission model TEE
??the dispersion tool ARIA Impact
Every September 22nd, the City of Paris takes part in a car free day called 'En Ville Sans Ma Voiture'.
In 2002 and 2003, the experiment was implemented in the historical centre of Paris (area concerned: 3 x 2 km). Between 7 a.m. and 7 p.m., this central area was only accessible to public transport, taxis, 'green' vehicles (LPG and electric cars) and professional users.
The experiment focused on assessing the impact of short-term road-side air quality. The background pollutant concentration, which is a regional parameter with strong weather dependence, sets the context. Airparif's experience prior to Ishtar has shown that the modelling tools must take into account detailed road geometry and traffic characteristics, in particular fleet composition and traffic congestion. The objective of the Ishtar case study was to test improvements to the modelling tools contained in the Ishtar suite.
Simulation results
Traffic, emission and dispersion of pollutants were estimated using models.
Traffic results
The traffic data were measured by loop detectors. The composition of vehicles in the central area of Athens was also available (e.g the proportion of two-wheelers and taxis increased in the central zone where other types of vehicles were banned).
Using these sources, Airparif's existing traffic model produces a coherent output for the car-free day in the central area. The traffic model provides hourly results with information regarding vehicle flux (number of vehicles by hour), mean speed (in km/h), capacity of the highway (in veh./h), saturation rate (in %) and cold start estimation (in % of vehicles).
The traffic model estimated that the traffic decreased by 11.5 % in volume (13.1 million of veh.km vs. 14.8 one week before) over all Paris. The drawback of this estimation is that to some extent it extrapolates the traffic change in the central area to the surrounding boulevards, while in reality these are more congested than normal during the traffic ban.
During the Ishtar project, an initial assessment was made using the VISUPOLIS traffic model.
Emission results
Impacts on emissions were estimated by our model. This model is based on COPERT 3 methodology and can provide emissions for 6 pollutants (NOx, CO, COV, SO2, PM and CO2) for each traffic link.
Global Assessment given by simulation a decrease of 13.6 % in emission of NOx (12.7 tons of NOx vs. 14.7 one week before).
Air quality results
The car free day impacts directly on the concentration of pollutants in the central area. For example, the concentration of NO2 measured at Quai des Célestins monitoring station significantly decreased reaching background levels, compared to the week before any measures were taken.
Conclusion
The Ishtar project provided the opportunity begin modelling congested traffic, using a new tool called Visupolis. Researchers also tested a new dispersion model (Aria Impact). An evaluation the impact of Car Free Day 2003 on Air Quality in the central area could be estimated at around a 60 % decrease in roadside pollution.
The case study concerns an Environmental Impact Assessment of a new infrastructure for the city of Imola, a municipality belonging to the province of Bologna.
The Ishtar modules used to carry out the case study are the Direct Impacts Module (TEE2004), the pollutants dispersion module ARIA IMPACT and the noise propagation module SOUNDPLAN.
The project estimated the impact on air quality of a new infrastructure framework for Imola, in order to provide a high level of environmental protection. Different infrastructural scenarios were studied to see which had the least environmental impact. It involved both direct interventions of traffic management (new paths, roadway adjustment, intersection regulation) and indirect interventions (public transport services, etc.).
The air concentrations of NOx, CO and PM10 from road emissions were modelled. These pollutants were chosen because of their important contribution to the photochemical smog and ozone formation. It offered the opportunity to test the suite as an integrated tool for supporting decision-makers in adopting environment-conscious actions.
Case study area/location
The proposed work concerns the 'Pedagna est-ovest' and will facilitate the movement of vehicles in the north-south direction.
Public participation involved a series of meetings during which citizens/committees proposed additional alternatives. Among the alternatives, some proposed by the Municipality and some by the local citizens, three have been modelled using the Ishtar Suite.
Collected data
The three scenarios were run for one single day, the 16th of January 2003, a day with a particular high concentration of PM10 due the unfavorable meteorological conditions. Hourly values for wind speed and direction, temperature and humidity were used.
Traffic data
The traffic data were provided by the Bologna province through measurement in the field and the simulation with the strategic model VISUM as it was already calibrated for the area under analysis. The average daily speed and flows profile was applied to all of the network links to obtain hourly flow rates and speed.
Traffic composition was determined using data from ACI (Automobil Club dItalia), which took into account the percentage of heavy duty vehicles measured on main roads.
ISHTAR modules used in the case study included:
Emissions
The CO, NOX, PM10 total emissions resulting from the TEE calculation in the morning and afternoon rush hours can give a quick comparison between the different scenarios. Alternative 5 was found to present the worst scenario in terms of emissions for all the pollutants.
Air Quality
The concentration of CO was reported without taking into account the background concentration at 5 pm for the Alternative 5 and the definitive Project. Alternative 5 has both a higher maximum value and a wider area with concentration higher than 300 mcg/m3 of CO.
Noise
The noise propagation simulation performed by Soundplan on the bases of the noise emissions calculated by TEE2004 provides the noise levels during the day (Lden) and during the night (Lnight) on the loudest side of each building. Soundplan requires as input, besides the noise emission levels, a detailed 3 dimensional map of the buildings and the population distribution (that can be made automatically by Soundplan on the basis of the number of inhabitants for a given area).
Conclusion
The province of Bologna case study tested the three core tools of the suite integrated in the Ishtar Suite. The case study was already run by the province but with the tools not integrated, and the results were obviously similar, with a clear advantage for the Definitive Project.
The three scenarios have been run using only the Ishtar Suite Interface. This test has been really useful for and the identification of bugs and necessary development and improvement of the integration SW. We expect to run also other tools based on this case study, in order to test the integration of the integration software for TEX, HIT, and the CBA.
This will be done in a follow up demo project of Ishtar.
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