Method and apparatus for transporting and housing tunnel workers active in high pressure environments

A method and apparatus for increasing the safety and productivity of tunnel workers active in high pressure environments is disclosed. The workers are housed at an intermediate pressure over a "work week" of at least several days and are transported between the tunnel face and the life support chamber in which the workers are housed in a pressurized personnel transport chamber. The housing contains sanitary, sleeping, decompression, storage and dining facilities and is generally located at the tunnel entrance. In the preferred embodiment, the intermediate pressure is about half of the tunnel working pressure but not more than about 20 psig and preferably less than 17 psig. It is expected that a decreased incidence of bone related diseases and bends will result due to the reduced number of full decompressions from the tunnel work environment.

This invention relates to a method and apparatus for increasing the safety 
and work output of persons working in a tunnel having a high pressure 
environment, and in particular to a method and apparatus for housing 
workers at a pressure intermediate the tunnel pressure and atmospheric 
pressure and for transporting them between tunnel work area and the 
housing structure. 
BACKGROUND OF THE INVENTION 
Tunnel workers often engage in activities in a high pressure environment, 
for example, a tunnel extending beneath a body of water or a tunnel 
extending into and through a mountain. Tunnel pressures in these 
environments often range as high as about 50 psig; and at pressures above 
about 11 psig, the tunnel workers are typically subjected to a daily 
compression/decompression cycle between tunnel pressure and atmospheric 
pressure. 
Tunnel workers, whether they work in a high pressure environment or not, 
typically follow a similar schedule. They work an eight hour shift; and if 
they are working at high pressures, a portion of the shift is spent in 
compressing from atmospheric pressure to the working pressure and another 
portion of the shift is spent in decompressing from the effects of high 
pressure according to readily available schedules or tables. However, 
repeated full decompression after each work period is time consuming, may 
provide the worker with a psychological crutch tending to promote 
absenteeism, and necessarily limits the effective work output per man-day 
by limiting the number of working hours per "eight hour work day". In 
addition, repeated full decompression exposes the worker to a higher 
incidence of the bends and is believed to result in a higher incidence of 
bone related diseases, for example, osteonecrosis bone neurosis. 
By borrowing from deep water diving technology, one might have expected 
that the effects of repeated full compression/decompression cycles could 
be successfully avoided. That technology teaches that the worker should be 
maintained at or near the high pressure found at the work area for an 
extended period of time, including non-work or "rest times". However, 
these diving systems have generally been directed to work activities at a 
depth of up to 1000 feet or more, where working pressures may be as great 
as 400 or more psig. Thus, while such systems have proven feasible and 
successful in connection with deep water projects, they still provide a 
relatively long decompression time when the worker leaves the pressure 
system because a full decompression from substantially the working 
pressure is still required. Thus the tendency to have adverse reactions 
such as the bends and increased incidence of bone related disease 
persists. The problem is compounded because the tunnel worker, unlike the 
diver, does not "stay under" until the job is done. Instead, he continues 
to work substantially his usual "work week". Additionally divers generally 
work in small groups, three to six man crews, whereas tunnel workers 
typically work in larger groups, for example, crews of twelve men or more. 
Consequently, the problem of repeated substantially full 
compression/decompression from tunnel work areas having high pressure 
environments remains and workers must either engage in work activities at 
high pressures less often or ignore the problems of repeated substantially 
full compression/decompression. 
It is therefore a principle object of this invention to provide a method 
and apparatus for allowing tunnel workers to engage in high pressure work 
activities without subjecting them to the increased risk of bone related 
disease. Other objects of the invention are to provide an efficient work 
structure whereby tunnel work in a high pressure environment may continue 
on a twenty-four hour basis, if desired, to increase work productivity, to 
provide apparatus which is relatively simple in structure and easy to 
maintain, to provide comfortable rest facilities for the tunnel workers, 
and to provide reliable apparatus capable of performing its function over 
long periods of time. 
A further object of the invention is to avoid a substantially full 
decompression from the tunnel pressure. 
SUMMARY OF THE INVENTION 
The invention relates to a method and apparatus for transporting and 
housing tunnel workers working in a tunnel work area having a high 
pressure environment. The method features the steps of housing the workers 
during non-work hours, over a plurality of working days, in a pressurized 
chamber maintained at an intermediate pressure less than the high pressure 
of the work area and greater than atmospheric pressure, and transporting 
the workers between the higher pressure work environment (or tunnel face) 
and the pressurized chamber in a pressurized personnel transport chamber. 
In preferred embodiments of the method, the intermediate pressure in the 
pressurized chamber is often less than about 20 psig and preferably less 
than about one-half the pressure at the work area, and the pressure in the 
pressurized transport chamber may be changed or varied between the 
intermediate pressure and the high pressure during the transporting step. 
The apparatus according to the invention features a pressurized life 
support chamber to house the workers for a plurality of days during 
non-work hours and pressure maintaining apparatus for maintaining the life 
support chamber at an intermediate pressure greater than atmospheric 
pressure and less than the high pressure of the work area. Also featured 
is a pressurized vehicle means to transport the workers between the life 
support chamber and the work area. The pressurized means and the life 
support chamber each have a connection means adapted to form a pressure 
tight seal between the chamber and the vehicle. In this way workers can 
transfer between the chamber and the vehicle and the ambient pressure of 
the chamber is maintained and is unaffected by the connection of the 
vehicle. The pressurized vehicle means and the work area each also have 
means to connect the vehicle to the work area to form a pressure tight 
seal between the work area and the vehicle. Thus the ambient pressure of 
the work area is maintained and is unaffected by the connection, and 
workers can transfer between the work area and the vehicle. 
In a preferred embodiment, the invention further features means associated 
with the pressurized vehicle to change the pressure in the vehicle in a 
controlled manner between the intermediate pressure and the work area 
pressure.

DESCRIPTION OF A PREFERRED EMBODIMENT 
According to the invention, a pressurized housing unit is provided, at a 
relatively low pressure which avoids the detrimental effects of repeated 
full compression/decompression. By housing the workers at a relatively 
low, intermediate pressure for an entire "work week", they soon become 
"saturated" at the intermediate pressure. Furthermore, even though the 
intermediate pressure is low, only relatively short 
compression/decompression times, if any are required, are needed during 
the excursions to and from the higher tunnel pressure. These excursions to 
and from the higher pressure are insufficient to cause bends or bone 
related disease and are short enough so that compression and 
decompression, if necessary, can be easily scheduled to take place during 
transport in a pressurized transporting vehicle. Furthermore, when a 
worker leaves the system, decompression from the "saturation" or 
intermediate pressure requires less time than decompression from the 
tunnel pressure, and more importantly, if the "saturation" or intermediate 
pressure is less than about 11 psig, it is believed that no decompression 
will be necessary. 
Referring to FIG. 1, the invention includes a human occupancy pressure 
vessel (HOPV) 10, which is a life support chamber comprised of a plurality 
of individual pressurized tanks 12a, 12b, 12c, 12d, 12e interconnected by 
a plurality of air locks 14a, 14b, 14c, 14d (See FIG. 2), and a personal 
transfer chamber 16, a pressurized transport vehicle designed, in the 
preferred embodiment, to transport workers between vessel 10 and the 
tunnel face of a work area (not shown) along tracks 18. 
Each of the pressurized tanks 12 is mounted on a mobile carrier 20 for easy 
transit from one working location to another. Typically the tanks 12 are 
positioned at or near the entrance to the tunnel and are raised on jacks 
22 to decrease wear of tires 24 and to level the tanks. A control facility 
26, at atmospheric pressure, is also provided on a mobile carrier for easy 
transport between work sites. The control facility provides the necessary 
communications with the vessel 10, safety monitoring and control equipment 
to maintain proper pressures in the vessel, control over decompression 
when needed, scheduling of various functions for the system, and any other 
required control function. 
Referring to FIG. 2, according to the preferred embodiment, the human 
occupancy pressure vessel comprises two storage and sleeping chambers, 
tanks 12b and 12d, a storage/decompression chamber, tank 12a, a sanitary 
chamber, tank 12c, and a dining and recreation chamber, tank 12e. The 
storage and sleeping chambers are identical in design and are identical 
with the storage/decompression chamber, tank 12a. Each of these chambers 
has a plurality of beds 30 (6 two level bunk style beds are shown), tables 
32, and lounge chairs 34. The pressure in the storage/decompression 
chamber, tank 12a, can be separately controlled by control facility 26 to 
effect a proper decompression schedule for workers who have completed 
their stay in the HOPV. In other embodiments of the invention, it may be 
desirable or necessary to change the configuration, number, or function of 
the tanks 12, for example, to provide each storage/sleeping chamber, or 
the entire chamber 10 with the capability of going through a decompression 
cycle. 
The sanitary chamber, tank 12c, includes means 36 for showering and all 
washroom facilities 38. The dining and recreation chamber, tank 12e, 
includes a table and chairs 40, and the various implements, dishes, and 
other equipment which a kitchen area would require. 
The HOPV 10 has, in the preferred embodiment, two entrances. The main 
entrance to the vessel 10, vessel entrance 50, is through an entrance air 
lock 52. The entrance area 53 is equipped with toilet facilities 54 for 
use by workers in tank 12a who are undergoing a decompression cycle as 
described in more detail below. The second entrance to the vessel, kitchen 
entrance 56, provides direct access to the dining area so that food and 
other provisions may be brought in without passing through the living 
quarters of the HOPV. 
The operation and control of the HOPV is directed from the control facility 
26 located near the HOPV. As noted above, facility 26 is not required to 
be maintained in a high pressure environment. The control facility is 
electrically connected to the HOPV and maintains the proper pressure and 
electrical requirements in the HOPV. An isobaric decompression control 102 
is provided to properly control decompression in tank 12a at the end of a 
"work week". A computer apparatus 104 is provided to maintain and monitor 
atmosphere and pressure and all other functions within the HOPV in order 
to insure proper safety for the men therein. A manual instrumentation 
control console 106 is provided whereby a single operator may monitor and 
manually control all functions within the HOPV. 
Entrance to the control unit is provided along entrance ways 106, 108 
leading from cat walk 110. The control chamber itself is generally an 
air-conditioned room in order to maintain temperature stability of the 
equipment therein. 
The HOPV disclosed in the preferred embodiment is designed to house 
thirty-six men for a substantial period of time. The thirty-six men would 
typically be divided into three twelve man crews, each crew working an 
eight hour shift. In this way, work can continue in the tunnel on a 
twenty-four hour basis if desired. 
If it is desired to have work continue at the tunnel twenty-four hours a 
day, seven days a week, one possible work schedule would provide for five 
twelve man crews, each crew working for six days, then resting for four 
days. The "on time" would be staggered so there would never be more than 
three crews in the HOPV at any one time. Other applications may require 
larger or smaller crews having the same or different work schedules. 
According to the preferred embodiment, a first twelve man crew, crew A, 
would begin by entering the lock at the face of the work area at day one, 
hour one. They undergo pressurization (compression) as is currently done, 
as is well known in the art, and work a normal shift of a total of eight 
hours. At the end of the shift, they would proceed to the face of the 
tunnel and enter the personnel transport chamber 16 which will transport 
them to the HOPV at the surface. The personnel transport chamber and the 
tunnel face 112 each have connections 114, 116 which when mated form an 
air tight seal and pressure lock. The pressure in the transport chamber is 
equalized if desired or necessary to the pressure at the tunnel face so 
that the workers may freely pass between the tunnel face and the transport 
chamber. As the transport chamber travels between the tunnel face and the 
HOPV, the workers may be decompressed to the storage pressure in HOPV 10. 
This may typically take one hour or less. If decompression is not 
necessary because the duration of the excursion to the higher pressure was 
sufficiently short, no decompression during transport will occur. 
Upon arrival at the HOPV, the personnel transport chamber is connected to 
tank 12c, the sanitary chamber. Coupling is effected by connections on the 
transport chamber and the HOPV which together form an air tight seal and 
pressure lock. By the time the transport chamber reaches the HOPV, its 
pressure is preferably equal to HOPV pressure and the workers may freely 
pass into the HOPV. In the HOPV, the crew typically first showers, 
changes, and then proceeds to the dining chamber, tank 12e. Since crew A 
will be decompressed first (they were the first to begin), they will 
occupy the storage/decompression chamber, tank 12a, during their "work 
week". This sequence of events is repeated for crew B (starting at hour 9) 
and crew C (starting at hour 17) except that they occupy the storage and 
sleeping chambers, tanks 12b and 12d respectively. 
On the twenty-third hour of the first day, crew A is transported back to 
the tunnel face in the personnel transport chamber to relieve crew C. The 
sequence continues in this manner until the decompression of crew A from 
the intermediate pressure begins. 
Decompression of crew A which normally starts after the sixth work period, 
begins on the second day for the first "work week" only. This allows the 
proper rotation of crews in the decompression chamber. Decompression 
starts immediately after the crew returns from the tunnel face. During the 
time required to decompress from the HOPV intermediate pressure to 
atmospheric pressure, the storage/decompression chamber, tank 12a, is 
sealed from the rest of the vessel. Meals are provided to the crew through 
the main entrance 50. The sanitary facilities 54 of entrance 50 are also 
accessible to the crew. When decompression is completed, crew A leaves the 
vessel 10, and a new crew, crew D, takes crew A's place in the tunnel. 
Crew D will work the full six day "week". 
The decompression chamber will be occupied by crew B when they return from 
their shift on the third day of the week and decompression of crew B 
begins after their work shift on the fourth day. A fifth crew, crew E, 
replaces crew B after decompression. Crew C occupies the tank 12a for 
decompression beginning on the fifth day of the week and begins 
decompression after their work shift on the sixth day. In this way a work 
schedule is designed to accommodate sequential change of crews so that 
work never stops in the tunnel. A new crew goes "under" every two days, 
when the oldest one decompresses. 
The number of crews and the hours they work can be arranged to meet 
whatever schedule is desired or needed. In the disclosed embodiment, each 
crew works for six days and is then off for four days. In addition, the 
crews rotate shifts, that is, a crew that works the first shift one 
"week", will work the third shift during the next "work week". 
Typically the pressures at the tunnel work area may be as high as 50 psig. 
It is believed that the HOPV should typically operate at a pressure 
approximately half the tunnel pressure, but not greater than about 20 
psig, preferably less than about 17 psig, and more desirably less than 
about 11 psig. It is believed that at HOPV pressures less than 11 psig, no 
decompression is necessary to leave the HOPV and at pressures less than 17 
psig, the occurrence of bone related disease as a result of decompression 
is eliminated. 
MAJOR ADVANTAGES AND UNOBVIOUSNESS OF THE INVENTION 
The invention is directed to a novel and non-obvious method and apparatus 
for transporting and housing tunnel workers who work in a high pressure 
tunnel environment. It provides a practical solution to the problem of 
increasing worker production while maintaining acceptable and satisfactory 
working and housing conditions. The method and apparatus depart 
significantly from the practices used in deep sea diving operations 
wherein divers are maintained substantially at the working pressure. In 
the claimed invention, the divers are housed and become saturated at a 
relatively low intermediate pressure, a pressure at which the risk of 
decompression sickness and the incidence of bone related disease is 
believed to be minimal (See e.g., Behnke and Jones, Preliminary BART 
Tunnel Results, In: Beckman, E. L. and D. H. Elliott, eds. 
Dysbarism-related osteonecrosis. Proceedings of a symposium of dysbaric 
osteonecrosis, Marine Biomedical Institute, University of Texas Medical 
Branch, Galveston, Tex., February, 1972, p. 25-40). 
The invention thus provides a method and apparatus for reducing the 
incidence of bone related disease and the bends due to repeated full 
decompression from tunnel pressures. The invention further advantageously 
provides a method and apparatus for working a tunnel which has a high 
pressure environment on a twenty-four hour basis, seven days a week, with 
a minimum number of men and maximum efficiency. 
The method and apparatus further advantageously provide sufficient rest and 
recreation facilities for successfully satisfying the psychological needs 
of tunnel work crews engaged in activities in high pressure environments. 
The method and apparatus of the preferred embodiment of the invention 
further advantageously provide apparatus which is mobile and which can be 
moved from one location to another with relative ease and facility. 
Other embodiments of the invention, including different constructions of 
the apparatus, will occur to those skilled in the art and are within the 
following claims.