Capítulo 3: Situar esta investigación en el marco de la Sociedad Actual
2. El nuevo escenario social de la educación
No direct danger for other tunnel users or the construct results from the transportation of hazardous goods (GGVSE [52]) and freights that can be compared with these goods if the safety regulations applying for such transports are observed.
In case of accidents and fires in the tunnel resulting from these, situations can arise particularly for the transportation of goods of dangerous goods class 1 (explosives) and dangerous goods class 2 (gases), which can only be dealt with by the fire brigade with great difficulty or not at all. Vehicles transporting flammable liquid materials of dangerous goods class 3 (e.g. petrol) can also lead to events that can no longer be dealt with by the technical equipment of the tunnel and emergency services due to the very high thermal powers of their freights.
Cargos that have comparable thermal weights and burn with an especially high development of smoke, but are not hazardous goods in terms of the GGVSE, can have corresponding effects.
The traffic authorities are responsible for possible restrictions for hazardous goods transports in road tunnels.
Prior to specifying or altering the regulations and requirements of hazardous goods transports through a tunnel, it is necessary to make a risk analysis according to Section 0.5 for tunnels that are longer than 400 m. Here, the stipulations of the International agreement concerning the carriage of hazardous goods by road (ADR) [53] must be considered.
If alternative routes for transporting hazardous goods or, if applicable, comparable cargos are available, they must be included into the risk analysis.
The results can have the effect that the probabilities of such an incident can be reduced and/or the extent of incidents can be limited by means of additional constructional, technical and/or organisational measures.
Help for the examination methods for deciding on possible restrictions for hazardous goods transports or transports with comparable cargos in road tunnels are provided in the common OECD/PIARC project ERS2 [54] and, in parts, the Swiss emergency regulations [55].
Appendix A: Lighting A1. Terms
The definitions and terms of DIN 67524 apply.
Furthermore, the following definitions apply:
Approach zone
The approach zone is located in front of the tunnel entrance, in front of the beginning of a roofing or grid ceiling built on to the tunnel.
The length of the approach zone generally corresponds with the stopping sight distance [56].
The adaptation luminance on the approach zone is determined by the luminance of the threshold zone and the glare of the bright tunnel surrounding. The closer the driver gets to the tunnel, the lower the adaptation luminance is in general.
The veiling luminance (equivalent veiling luminance) in the approach zone, which must be used as a basis for determining the luminance in the tunnel, depend on
- the stopping sight distance - the viewing direction taken - the size of the tunnel opening
- the orientation of the approach zone and the glare during unfavourable positions of the sun - the built-up space in an angle range of 16°
around the viewing direction and the reflection properties
- the type of tunnel (e.g. short, long tunnels)
- the angle of vision under which the threshold zone appears from the stopping sight distance.
The veiling luminance is defined as the difference between the adaptation luminance and the road luminance. It results from the evaluation of the luminances of the environment according to the laws of the physiological glare, which describe the diffused light generation in the eye. The diffused light interferes with the retinal image, reduces its contrasts and increases the adaptation luminance.
Threshold zone
The threshold zone follows the approach zone. It begins at the tunnel entrance and must at least have the length of the stopping sight distance.
The adaptation luminance decreases in the course of the passage through the threshold zone.
Transition zone
The transition zone is located behind the threshold zone. In this area, the luminance level is reduced to the luminance of the interior zone. The length of the transition zone results from the reduction of the adap-tation luminance in the course of the passage through the threshold zone and the decreasing lumin-ance in the transition zone. It depends on the speed.
Interior zone
The interior zone follows the transition zone and leads close to the exit portal. The luminance level is kept constant in this entire zone, while sufficient visibility must be ensured.
Figure 26: Terms and schematic development of the luminance when passing through a tunnel at daytime
Exit zone
The exit zone extends from the end of the interior zone to the tunnel exit. It begins where the vision or the adaptation luminance is influenced by the brightness outside the tunnel.
Counter-beam lighting
Counter-beam lighting (CBL) is characterised by the fact that the luminous intensity distribution of the lights mainly is oriented against the direction of traffic.
Symmetrical lighting
Symmetrical lighting (SL) is characterised by the fact that the light intensity distribution of the lights is symmetrical in the direction of traffic and against the direction of traffic.
Maintenance value
The maintenance value of a light-technological quality characteristic is the value that must at least be achieved at any time of operation of the lighting system.
Planning value
The planning value of a light-technological quality characteristic is the value for which the planning of the lighting system must be designed in order to ensure that the minimum maintenance value of the quality characteristic always is achieved. A main-tenance scope and cycle corresponding to the latest developments of technology is presupposed here.
Luminance at the beginning of the approach zone L20
Average luminance in a circular area of observation, whose centre lies in the centre of the tunnel opening, but no more than 2.50 m above the road level, and which appears within an opening angle of 20° from the eye level of the approaching vehicle driver from the stopping sight distance before the tunnel portal.
Luminance in the transition zone Ltr
Average road luminance of a transverse strip of the road at a predefined position within the transition zone.
Luminance in the interior tunnel zone Lin
Average road luminance of a transverse strip of the road at a predefined position within the interior tunnel zone.
Luminance ratio k
Ratio that the luminance in the 20° evaluation field L20 bears to the road luminance in the threshold zone Lth. k is a measure for the luminance difference that a vehicle driver experiences at the tunnel portal when entering the tunnel.
Threshold value increase TI
The threshold value increase characterises the increase in the recognisability threshold due to the effects of the tunnel lights; it is a measure for the physiological glare. Further information on the threshold value increase TI can be found in [57].
Table 14: Typical values of the luminance in the approach zone
Average luminance L20 in a 20° field of vision (cd/m2) Proportion of sky
35% 25% 10%4) 0%4)
Low High Low High Low High Low High Brightness in
field of vision 1) 1) 2) 2)
Stopping sight distance
60 m 3) 4000 5000 2500 3500 1500 3000
Stopping sight distance
100 to 160 m 4000 6000 4000 6000 3000 4500 2500 5000
1) Effect mainly depends on tunnel orientation. Low: direction of traffic to north; high: direction of traffic to south. For entry from the west or east, an average value between low and high must be selected. For entry from the directions northwest, northeast, southeast and southwest, the luminance must be determined in the same way.
2) Effect mainly depends on the brightness of the environment. Low: low level of reflection of the environment; high: high reflection level of the environment.
3) For a stopping sight distance of 60 m, a proportion of sky of 35% does not occur in practice.
4) For regions with frequent snowfall, the luminance values at 0% and 10% proportion of sky must be set 10% higher.
A2. Calculation methods
Determination of the luminance in the approach zone at daytime
The luminance at daytime L20 in the approach zone is used as a calculation parameter for the visibility conditions in the approach zone, since it can be acquired at low costs and without errors in practice and because it is sufficiently exact for the control of a tunnel lighting system. For the luminance L20, that value must be specified that is not exceeded during 90% of the year. If this value cannot be determined from meteorological data, L20 can be determined by means of the approximation methods described in the following.
Other light-related planning values, e.g. the equivalent veiling luminance (for a definition, see DIN 67524-2), must not be used as calculation parameters as long as no suitable devices are available for measuring these values.
A2.1 Approximation methods for determining L20
in case of an unknown composition of the evaluation field
The approximation method displayed in Table 14 must be used if the composition of the evaluation field in not known, but the proportion of sky can be estimated. The method thus only represents a rough estimation. The values are based on empirical studies and are valid for a frequency of the operating time within one year for the most frequently arising operating conditions of a tunnel of 95% at the most.
A2.2 Approximation method for determining L20 if the composition of the 20° evaluation field is unknown
With this method, L20 is calculated with the help of a scaled drawing of the surroundings of the tunnel entrance or on the basis of photographs and the following formula:
L20 = γLC + ρLR + εLE+ τLth. (8) LC = the luminance of the sky;
γ is the proportion of sky in percent LR = the road luminance;
ρ is the proportion of the road in percent LE = the luminance of the surroundings;
ε is the proportion of the surroundings in percent Lth = the luminance of the threshold zone; τ is the
proportion of the threshold zone in percent.
At a good approximation, the influence of the luminance of the threshold zone can be ignored;
thus, the following applies:
L20 ≈ γLC + ρLR + εLE. (9) In order to determine the surface ratios which are required for calculating L20, a photo must be taken from stopping sight distance at every tunnel entrance. With a known size on the picture, e.g. the tunnel height, the diameter of the L20 cone in the photo can be determined. If the tunnel has not yet been built, it is still possible to use a photograph as long as the horizon will not be altered too much due by the construction. Otherwise, a scaled drawing should be used. The individual surfaces on the photo or the drawing (rock, sky, building) can be classified as proportions of the entire L20 area.
If the luminances of the surrounding are not available, the data for LC, LR and LE (in cd/m3) can be taken from Table 15.
Table 15: Luminance values for the proportions in the L20 area
LE (environment) in cd/m2 Direction of
traffic LC (sky)
cd/m2 LR (road)
cd/m2 Rock Building Snow1) Grass
North 8000 3000 3000 8000 15000 (V, H) 2000
East-west or west-east
12000 4000 2000 6000 10000 (V)
15000 (H)
2000
South 16000 5000 1000 4000 5000 (V)
15000 (H) 2000
1)V refers to vertical, H to horizontal surfaces.
Appendix B: Ventilation B1. Basics
The following specifications are based on average values of the traffic composition or the respective vehicle category (car (petrol), car (diesel), HGV).
B1.1 Basic values
In order to determine the fresh air demand, the basic values according to Table 16 can be used. Between the years 2000, 2005, 2010, 2015 and 2020 it is necessary to interpolate linearly. From the year 2020, the basic values remain unchanged according to today's regulation status.
The basic values refer to the emissions at sea level at an average speed of 60 km/h. They depend on the vehicle weight, motor construction, age and maintenance condition of the vehicle. Thus, only an average value of the vehicle group can be used.
B1.2 Calculation parameters of the air quality in road tunnels
The amount of additional fresh air that must be introduced into the tunnel in standard operation is calculated for a given traffic situation from the vehicle emissions and the predefined assessment concentrations of the determining contaminants according to Table 7. The amount of contaminants in the tunnel air is determined with the guide gas carbon monoxide CO and the visibility with the guide substance diesel smoke.
B1.3 Determining road accidents
The calculation of the CO or haze emissions is performed for every lane individually. The dimen-
sioning of the ventilation for flowing traffic generally must be adjusted to the forecast traffic figures in general, while the maximum average hourly values are decisive. In cases in which frequent stagnant traffic or traffic jams must be expected, the maximum possible traffic volume according to Table 6 must be used in consideration of the driving speed of the HGVs.
B1.4 Limit speed of the HGVs
The driving speed must be determined by the correlation VF = Vlimit or VF = 1.1 * Vperm. Here, the smaller value is decisive. Vlimit is provided by the values in Table 17.
For values between the specified tendencies, it is necessary to interpolate linearly.
B1.5 Proportion of cars with diesel engine
For the composition of the vehicle pool, the proportion of cars with diesel engines of the total number of cars is important. When dimensioning the ventilation, project-related data for the composition of traffic must be used if possible. If no detailed data is available, a proportion of the diesel vehicles of 20 percent of the cars can be assumed.
B1.6 Mass factor for HGVs
The basic emission values of the HGVs apply for an average weight of the heavy-goods vehicle traffic to be expected of 10 t. For heavier vehicles, a speed-related mass factor must be considered. 75% of the weight limit for the tunnel stretch (Table 18) must be used as average HGV mass. For values between the specified masses, a linear interpolation is required.
Table 16: Basic values of the CO emissions (qCO) and haze emissions (qτ) at a speed of 60 km/h at sea level
Year 2000 2005 2010 2015 2020
Medium CO
Table 17: Limit speed of HGVs for uphill and downhill grades
Inclination I [%] -6 -5 -4 -3 -2 -1 0 1 2 3 4 5 6
B1.7 Consideration of special conditions
Wind hitting a tunnel portal as well as thermally caused density differences between the tunnel air and the surrounding air can have significant effects on the tunnel ventilation. These effects thus must be checked and, if necessary, considered when dimensioning the tunnel ventilation.
- Wind pressure on the tunnel portals
In order to determine the wind pressure, the wind speed and direction distribution generally measured at 10 m above ground is assumed. The basis for dimensioning is the 95 percentile of the wind component directed vertically to the tunnel portal.
When determining the wind hitting the tunnel portal, the friction-related gradient of the wind speed as well as the location of the portal in a recess, if applicable, must be taken into consideration. The decisive wind pressure equals the resulting impact pressure of the wind hitting the portal surface.
- Effect of the natural lift and negative lift as well as the thermal lift in the event of a fire
In tunnels with longitudinal slope, temperature differences can cause a lift or negative lift, which must be considered for planning the ventilation. The determining natural temperature differences depend on the local conditions. The temperature difference decisive in the event of fire refers to the rated thermal power and the assumed expansion of the fumes at the time of the blazing fire.
B2. Carbon monoxide emissions
B2.1 Calculation procedure
The amount of fresh air required per lane for meeting the permitted CO concentration in the tunnel is calculated by means of the following formula:
QZL =
⋅
When calculating the CO emissions (ECO), differentiations are made between cars with petrol or diesel engines and HGVs. The calculation formula for a lane is as follows:while the following applies:
QZL = required amount of additional fresh air per lane and kilometre [m3/s, km, lane]
N = traffic density of the vehicles per kilometre and lane [veh/km, lane]
N = M/vf at flowing traffic with M = traffic volume [veh/h, lane]
vf = average driving speed on lane [km/h]
COperm = permitted CO concentration in ppm according to table 7
xHGV = proportion of HGVs [%]
B2.2 Influences by speed, inclination and height The required motor power and the working point in the motor characteristics change at other driving conditions compared with the basic value condition.
These influences differ according to vehicle and must be determined as average values.
B2.2.1 Influence of speed and inclination
Tables 19 to 21 show the influences with respect to the basic value for the driving conditions standstill (idling), stagnant driving with different average speeds and fast driving. Intermediate values must be interpolated linearly.
Table 19: Inclination and speed factor fiv [-] for CO of cars with petrol engine
Table 20: Inclination and speed factor fiv [-] for CO of cars
Table 21: Factor of inclination and speed fiv [-} for CO of HGVs
Inclination [%] B2.2.2. Influence of height
The factor for considering the height factor must be taken from Table 22. For values between the specified heights, it is necessary to interpolate linearly.
Table 22: Influence of the height above sea level on the CO emission
The permitted CO concentrations in Table 11 are expressed in ppm. The following applies: 1 ppm = 1 part per million = 1 cm3 exhaust per m3 air or 10-6 m3 exhaust per 1 m3 air.
Outside air has an initial level of carbon monoxide.
For interurban tunnels, it can be up to 2 ppm, for urban tunnels with high traffic volumes, it can be up to 5 ppm and in disadvantageous cases up to 15 ppm CO.
If outside air is pumped into a second tube or an additional-air construction directly next to a portal with escaping tunnel air, significant ventilation shorts can occur without the provision of certain measures.
A separating wall between neighbouring tunnel portals can help here.
External air suction stations should be positioned with sufficient distance to the air jet escaping from the tunnel.
B3. Impairment of vision
B3.1 Definition of the impairment of vision
A eam of light is weakened when it passes through clouded air, which can be recorded as follows:
E = Eo + e-K*L. (14)
where:
E = light flow after passage through clouded air Eo = light flow before passage through clouded
air
K = extinction coefficient [l/m], measure for clouding of vision
L = length of the penetrated layer [m].
B3.2 Calculation method
The calculation of the demand in air for thinning the smoke is based on the clouding emitted by a diesel engine. Due to the downward development of emissions of motor soot, the emissions from tyre abrasion and resuspension of particles must be considered for calculating the clouding of vision in the future. This must no longer be ignored. The demand in air thins the clouding to the permitted level of clouding K in the tunnel. The basic value of the clouding emission in m2/h per vehicle is the product of the emitted amount of exhaust fumes in m3/h and the level of clouding K in l/m.
The calculation formulation for a lane for determining the demand in additional fresh air for observing the permitted air clouding is as follows:
QZL = ⋅
where the following applies:
QZL = required amount of additional air per lane and kilometre [m3/s, km, lane]
N = traffic density of the vehicles per lane and kilometre [veh/km, lane]
N = M/Vf, for flowing traffic with M = traffic volume [veh/h, lane]
Vf = average speed on lane [km/h]
Kperm = permitted concentration of clouding [l/m]
according to Table 7
B3.3 Influence due to speed, inclination and height
The haze emission for other operating conditions of diesel engines than in the basic case is acquired with the help of tests with correction factors. Here, a differentiation is made between cars with diesel engines and HGVs. The haze emission at the exhaust pipe of the cars with petrol engine can be
The haze emission for other operating conditions of diesel engines than in the basic case is acquired with the help of tests with correction factors. Here, a differentiation is made between cars with diesel engines and HGVs. The haze emission at the exhaust pipe of the cars with petrol engine can be