Dear Valdir

I think that is very difficult to find statistics about this event.

In Italy i don't find statistics about this event.

For this case ( under ground) the Italian fire regulations impose :

A sprinkler plant (UNI 12845) for each level; (also for only one parking level, like under a building of 5 level. The trigger is 9 cars or 300 mq )

A REI 120 compartimentation for each level ( REI 120 Ceiling );

A protected escape way for people at each level.

Emergency light system, at least 30 minutes.

REI 120 Doors for each level with automatic closure driven by a fire/smoke revelation system. (This depend from the risk analisys)

On important depth, an automatic smoke evacuation system.

Considerations

If the ramp is enclosed in the structure ( case without open ceiling) it work like a bus between levels.

Is not certain the flames propagation from a level to superior levels.

It is very possible that smokes can invade all the levels.

I am sorry. I don't know! This is not in my research field.

A. Hajilouy Benisi

Dear Dr. Silva

I try to give you some suggestions from Italian fire prevention regulations.

Here garages are defined privates or publics and according to their size (surface, square meters).

In particular class EB defines garages of size ranges from 1000 and 5000 m2 and EC stands for garages of size greater than 5000 m2.

Moreover a garage could be defined "isolated" only if is placed in a dedicated building and if is separated from aother buildings with compartmentation measures of lperformance level equal to 2. According to italian regulations this stands for conditions in which propagation to other compartments or other activities is avoided and fire propagation in compartment is contrasted for an adequate period of time, coherent with fire duration.

All aother typologies of garages are defined as "mixed".

As regarding compartimentation there are two prescriptions: 

-mixed garages have to be placed in indipendent compartment with respect to the correspondant building;

-garages defined as EB, EC are to be placed in a smokeproof compartment with respect to the building in which are placed.

This could be useful to you just for doing a sort of filtering of cases which do not represent your situation.

If you want a statistical study on fire propagating in car park you could take a look at this work:

Li Y, Spearpoint M J. Analysis of vehicle fire statistics in New Zealand

parking buildings. Fire Technology

I hope this could help you, 

Best regards

Dear Valdir

Italy is home of law.

I attach the Italian fire prevention rule, DM 01/02/1986, the google translator may be useful.

The Italian administrative classes, released 01/08/2011, are 3 :

300-1000 mq, 1000-3000 mq , >3000 mq (Treshold on Surfaces)

The National rule, based on cars number, start from 1 cars. (Treshold 1-9 Cars, > 9 cars)

So happens that :

The parkings with area less than 300 mq are subject to national rule (DM 01/02/1986 art.2) but not to approval by National Fire services.

The parkings with area greater than 300 mq are subjects to approval by National Fire services, with rules principally based on number of cars.