Simulation of the traffic situation in Tallinn

Simulations were done by using Airviro program specially developed by Swedish company Indic. Before to start simulations you have to describe situation on the streets and make necessary approximations.

To describe roads and streets two kinds of road were defined:

1.         Through road:
            10% of Heavy vehicles (Trucks and busses)
            15% of Light vehicles with catalysator (assumed that catalysator works properly)
            30% of cars produced in Russia or former Soviet Union
            45% of imported cars without catalysator.

2.         Residential road:
            1% of Heavy vehicles (Trucks and busses)
            18% of Light vehicles with catalysator (assumed that catalysator works properly)
            33% of cars produced in Russia or former Soviet Union
            48% of imported cars without catalysator.

 Calculations are done by three scenario:

1.       Current situation;

2.       Situation in the year 2005 if traffic regulation is not changed but there is some changes in the cars (number of cars equipped with catalysator will increase, number of old Russian cars will decrease).

3.       Changes in the traffic regulation and in the cars are taken into consideration.

Data for streets (cars per day, length of link) are from Stratum company. Day type variation is presented in the figure 1 and it is assumed that those data can be used for both road types. Day variation for Saturday and Sunday is calculated from Swedish database using relative ratios. Yearly variations for roads are given in tables 1 and 2 below.

Figure 1

Number of cars per day for concrete street is calculated from model developed by Stratum company. It is assumed that number of cars during morning rush hour is 10% from all cars using the link.
Gases emitted from Russian cars was taken according to the report of Moscow Institute for Traffic and Engines and data for other cars were transferred straight from Swedish database.

Vabaduse puiestee

Vabaduse puiestee, Hiiu, Õie and Valdeku streets were defined as through road. All other streets and roads crossing or parallel with Vabaduse puiesetee were defined as resident roads. Average speed of through road was 50 km/h and 1 stop per link. Average speed of resident road was 40 km/h and 3 stops per kilometer.

Table 1. Change of cars in the Through Road (%)

Table 2. Change of cars in the Residential Road (%)

Northern Tallinn

Narva road (from Russalka to Jõe street), Tartu road (to Pronksi street), Jõe, Pronksi, Ahtri streets and Põhja puiestee are defined as through roads. All other are resident roads. Streets in the City center are defined as resident roads because heavy traffic is limited there (except busses). According to the scenario, by year 2005 Narva road is changed to resident road assuming that most heavy traffic will use new Põhja-Väil road. Average speed on the Põhja-Väil road is assumed to be 50 km/h.

Results

Two different way to present data is used:

* Mean             Average substance concentration in the calculated time period.

* Perc99           The highest concentrations of substances, omitting 1% of the highest values as possible errors.

Meteorological data are taken from database collected during summer from Meteomast. Because of lack of wintertime data, calculations were done only for summer time.

Threshold Limit Values (TLV) for substances:

NO_X:     TLV_max - 400 mg/m³; TLV_24h -150 mg/m³

CO:        TLV_max - 5000 mg/m³; TLV_24h - 3000 mg/m³

TLV for VOC is not determined because of complicated composition of gases.

Figure 2

Conclusions

Vabaduse puiestee: Reconstruction of Vabaduse puiestee does not improve environmental situation in the region. Better impact to the environment will be due the changes in the cars.

Northern-Tallinn: One of the results is shown in the Figure 2. In the picture mean concentrations of NO_X are presented. Threshold Limit Value is exceeded only on the cross-road with Narva road where the new road will start. Overall situation in the centre of Tallinn, specially on the Narva road where TLV is exceeded in many places already nowadays, is definitely improving. Isolines shows concentrations where there is higher concentration of substance inside of the isoline and smaller outside. Value of the isoline is shown on the line. Building a new road will make significant change from the point of view of air quality.

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