Machine for transport of passengers and cargo

RELATED APPLICATIONS

This application is divisional of application Ser. No. 09/475,867, filed on Dec. 30, 1999, now patent 6,401,625; which is a continuation-in-part of application Ser. No. 08/921,180, filed on Aug. 29, 1997, now U.S. Pat. No. 6,039,135; which claims benefit of application No. 60/025,451, filed on Sep. 5, 1996.

TECHNICAL FIELD

This invention relates in general to mass transportation devices and in particular to a mass transportation system including a guideway and vehicles capable of use both on conventional roadways and the guideway of the mass transportation system.

BACKGROUND ART

Mass transportation systems have been developed and proposed for a variety of transportation vehicles. In one, the system uses vehicles that are carried by a cable or track and which stop for passenger or cargo pick-up and drop-off automatically upon demand. The demand is made known to the system by either human input of some type or computer program. Such systems have been used and proposed for use in high traffic density situations. These systems have been designed for relatively low-speed operations and for relatively short distance applications such as within airports and in downtown areas. Vehicles for such systems have been carried on tracks or guideways. Switching of vehicles from track to track or guideway to guideway has generally been accomplished by employing movable track or guideway elements.

Vehicles designed for such use may be used only on the tracks or guideways for which they are designed. Use of the tracks or guideways is also restricted to system captive vehicles designed only for track or guideway use. Some limited-use vehicles have been designed for dual road and track use under manual control. Examples of such a vehicle are normal road use trucks equipped with separate wheels to allow them to be driven by railroad maintenance personnel along railroad tracks under manual control. Some normal road-use motor vehicles have been adapted with either mechanical steering arms designed to cause the car to follow a steering rail mounted along a special roadway, or electronic sensors designed to cause the car to follow magnets or electrified wires embedded in road pavement. Several disadvantages are inherent in these past systems, including the following:

1. Some of the systems are capable of providing service only between stations and are incapable of providing door-to-door service to passengers and cargo.

2. Systems designed to allow specially equipped motor vehicles to operate on automated guideways have not provided on-demand or scheduled station-to-station service for non-motor vehicle passengers.

3. Inability to provide door-to-door service for passengers and cargo greatly restricts the usefulness of station-to-station systems that use track or guideway only vehicles. Provision of such systems makes it necessary to employ other means such as conventional motor vehicles or trucks either instead of or in addition to the system. Such motor vehicles and trucks cause pollution of the atmosphere and require expensive and usually parallel networks of roads and highways.

4. In order to enable operation under the full range of weather conditions, track or guideway based systems must either be located in expensive tunnels or completely covered.

5. Trackways or guideways for past systems have been expensive to build because of needs to provide extensive land grading or massive structural supports for heavy elevated trackways or guideways.

6. Because past automated track or guideway based systems have been designed for relatively short range or low speed operations, they have not been practical for high-speed, long-distance operation. Thus, it is necessary to transfer passengers and cargo between vehicles for transportation over other than relatively short distances.

7. Because of items (1) and (6) above, past rail or guideway based systems using captive vehicles have not provided capability for long-distance, door-to-door service for passengers or cargo.

8. Individual passenger security and privacy are not provided during travel in systems in which relatively large vehicles are used.

9. Automatic point-to-point transportation of cargo is not provided via the same systems providing passenger travel.

10. Systems capable of providing station-to-station passenger service have been unable to accommodate dual mode road use and trackway or guideway use vehicles.

Another system uses special railroad cars equipped with wheel ramps arranged to allow motor vehicles to be driven onto and off of the railroad car for transport. Such cars and ramps are designed to carry several motor vehicles over conventional railroads. Ramps are also used at loading and unloading points to allow the cars to be driven onto and off of the rail cars. This system has several disadvantages, including the following:

1. The railroad cars are designed to carry a multiplicity of empty motor vehicles rather than one motor vehicle with passengers.

2. The special railroad cars are designed to operate on conventional railroads rather than on an automated guideway.

3. The ramps for entry and exit of motor vehicles to the railroad cars are not designed to allow empty railroad cars designed to transport motor vehicles to pass freely under the entry and exit ramps to reach and leave the motor vehicle loading position.

4. The railroad cars are designed to be pulled by conventional railroad engines as parts of conventional railroad trains rather than operating alone under automated control under their own power and control on an automated guideway system.

Still another system proposed makes use of dual mode cars for both conventional road and guideway use. This dual mode car is conveyed by a monorail and has a set of separate street wheels for street use. This car has a wide, lengthwise section down the center of the car to accommodate the monorail and can only fit passengers on either side of the car. The monorail drive wheels are complex.

What is needed is a single system for rapid and efficient transportation of passengers and cargo both on a door-to-door and station-to-station basis for either short range or long-distance.

DISCLOSURE OF INVENTION

This invention relates to a set of machines for automated transportation of passengers and cargo along special guideways, and for nonautomated transportation of passengers and cargo on conventional streets and roads with provisions for use of the same vehicles for both guideway and road applications and without transfer of passengers or cargo between vehicles when transferring between roads and guideways. The guideway has a pair of rails enclosed by a shroud. A slot extends longitudinally through an inner side wall of each of the shrouds. The vehicle wheels are carried within the shroud on wheel contacting surfaces, with ends of the axles extending through the slots. An electrical bus bar is located within the shroud for providing power to the vehicle. A communication strip is located within the shroud for transmitting to and receiving signals from the vehicle.

The dual-mode vehicles of this invention have axles that are extensible from a retracted position to an extended position. In the extended position, the wheels will locate within the enclosed rails. In the retracted position, the wheels recess within wheel wells of the vehicle for conventional street use. Other vehicles of this invention are dedicated for use only on the guideway. Conventional vehicles may also be used on the guideway by loading them on automated ferries that move along the guideway.

Both dual-mode and guideway only vehicles are automatically controlled during guideway use. The vehicles and guideways are designed to provide protection from weather elements including snow, sleet, ice, and rain accumulation that would interfere with operation of the vehicles on the guideways. The design of the vehicles and guideways are such that switching of vehicles between guideways and on and off of the guideways is accomplished without discontinuities or moving parts in either the guideways or the guideway switching mechanisms.

The automated car ferry vehicle is designed to hold and carry a single conventional motor vehicle with passengers on the tracked automated transportation system. The system also has special ramps for loading and unloading the motor vehicles onto the ferries from conventional streets and roads. A cargo version of the ferry is adapted to carry conventional sea-land cargo containers.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1

is a perspective view of a dual-mode vehicle constructed in accordance of this invention and shown with the wheels in a retracted position.

FIG. 2

is a perspective view of the vehicle of

FIG. 1

, showing the wheels in an extended position.

FIG. 3

is a perspective view the vehicle of

FIG. 1

shown within a guideway constructed in accordance with this invention.

FIG. 4

is a perspective view of the guideway shown in FIG.

3

.

FIG. 5

is a schematic view of the vehicle of FIG.

1

and the guideway of

FIG. 3

, the guideway being shown in cross-section.

FIG. 6

is a schematic cross-sectional view of the guideway as shown in

FIG. 5

, but showing a cargo vehicle located on the guideway.

FIG. 7

is an enlarged sectional view of one of the rails of the guideway of

FIG. 4

, with one of the wheels of the vehicle of

FIG. 1

shown therein.

FIG. 8

is a side sectional view schematically illustrating a platform and ramp for loading conventional motor vehicles onto ferries for use on the guideway of FIG.

4

.

FIG. 9

is a view of the platform and ramp of

FIG. 8

, but showing a dual-mode vehicle being driven onto the guideway.

FIG. 10

is a schematic view illustrating electrical controls for the ferry used with the guideway of this invention and also illustrating controls for a conventional motor vehicle to be carried on the ferry.

FIG. 11

illustrates a keypad that is a portion of the driver control unit of FIG.

10

.

FIG. 12

is a top view of one of the rails of the guideway of

FIG. 4

, showing an end joint.

FIG. 13

is the schematic view of an inspection station for the guideway of FIG.

4

.

FIG. 14

is a top view of the guideway of

FIG. 4

, showing a ferry located thereon, with a motor vehicle loaded on the ferry.

FIG. 15

is a schematic front view of the ferry and motor vehicle of FIG.

14

.

FIG. 16

is a perspective view of a sea-land cargo container being carried on a ferry on the guideway of this invention.

FIG. 17

is a schematic sectional view of the cargo container, ferry, and guideway of FIG.

16

.

FIG. 18

is a side view of the cargo ferry of

FIG. 16

, with the container removed and wind resistance reducing end caps in a storage position.

FIG. 19

is a side view of the cargo container of

FIG. 16

being loaded on the ferry.

FIG. 20

is a side view of the cargo container of

FIG. 16

shown in a loaded position.

BEST MODE FOR CARRYING OUT THE INVENTION

Referring to

FIG. 1

, a dual-mode vehicle

11

is constructed for use on conventional roads and also for use on an automated guideway system. Vehicle

11

has a body

13

with four wheel wells

15

. Wheels

17

are recessed as shown in

FIG. 1

for conventional road use. Wheels

17

are extensible to the position shown in

FIG. 2

for use on the automated guideway system of this invention.

Referring to

FIG. 7

, wheels

17

are supported on axles

19

. Each axle

19

is extensible from the retracted position shown in

FIG. 1

to the extended position shown in FIG.

2

. The extension and retraction may be accommodated in several manners. Preferably the mechanism will include telescoping members that are moved between the two positions by hydraulic cylinders (not shown). Also, each axle has a hub end

19

a

that is offset and higher than a central portion

19

b

. The axis of rotation of central portion

19

b

will be located below the axis of rotation of wheel

17

and hub end

19

a.

Referring again to

FIGS. 1 and 2

, vehicle

11

also has a set of electrical power and communication devices

21

mounted on each side adjacent to the front wheel

17

. Electrical devices

21

also move between extended and retracted position as shown in

FIGS. 1 and 2

. Electrical devices

21

will recess within one of the wheel wells

15

while in the retracted position. In the extended position, electrical devices

21

extend out to the outer edge of wheel

17

for receiving power and communicating with the automated guidance system. As shown schematically in

FIG. 7

, electrical devices include three power conductors

21

a

and a communication device

21

b

, such as an antenna or an optical signal transmitter/receiver. Referring to

FIG. 5

, dual-mode vehicle

11

has an electrical motor

23

, shown schematically. Motor

23

supplies the power to drive wheels

17

both while on conventional roadways and also on the automated guideway. While on conventional roads, a series of batteries

25

provide power for motor

23

. A controller

27

controls the speed of motor

23

through a transmission (not shown). Controller

27

also controls a brake system

29

. For conventional roads, a throttle pedal (not shown) will be used by the driver to control controller

27

, and a brake pedal (not shown) will be used to control the brake system

29

. Furthermore, a steering wheel

30

is employed on conventional roads for turning front wheels

17

. On the automated transport system, controller

27

cuts off power from batteries

25

and power from the automated system will be supplied to motor

23

. Furthermore, signals from the automated guideway system will operate the brake system

29

and steering system

30

through the electrical devices

21

.

FIGS. 3 and 4

illustrate guideway

31

of the automated system. Guideway

31

comprises a pair of parallel rails

33

. Rails

33

are supported by cross members

35

, which in turn are mounted to posts

37

. The spaces

39

between rails

33

and between cross members

35

are open to allow sunlight to pass through to the ground. The longitudinal distance from one cross member

35

to another is substantially greater than the width from one rail

33

to another. As shown in

FIG. 3

, wheels

17

of dual-mode vehicle

11

will locate within each of the rails

33

.

Referring again to

FIG. 7

, each rail

33

has a main support member that is a channel member

41

. Channel member

41

is preferably steel and has upper and lower flanges

43

,

45

and a sidewall

47

. Flanges

43

,

45

are parallel to each other and perpendicular to sidewall

47

. Sidewall

47

is located on the outer side with flanges

43

,

45

extending inward.

A support member

49

mounts to channel member

41

for providing support to wheels

17

. Support member

49

has a flat base

51

with a tread or track

53

located on top. Base

51

has a depending lip

55

on its outer side. Lip

55

fits within a slot provided by a bracket

57

mounted to the inner side of sidewall

47

. Support member

49

has a depending leg

59

that extends from the inner edge of base

51

downward into engagement with channel member lower flange

45

. Support member

49

can be readily removed by pulling lip

55

upward from bracket

57

.

Support member

49

defines a chamber

61

between it and lower flange

45

. Power cables

63

for supplying power extend through chamber

61

. Also, communication or signal cables

65

extend through chamber

61

. Power cable

63

and communication cables

65

could be joined in a single cable, if desired. Power cable

63

communicates with a power bus bar

67

. Also, in addition to communication cables

65

for control of vehicles on guideway

11

, space exists for telecommunication cables for general purpose use, independent of guideway

11

. In this embodiment, three separate longitudinally extending conductors

68

make up bus bar

67

, because the preferred power supply is three-phase AC. Each of the conductors

68

is mounted to an insulator

69

. Insulator

69

secures to the interior of sidewall

47

by means of clips

71

. Clips

71

locate within a bracket

73

secured to sidewall

47

. Conductors

68

are adapted to be slidingly engaged by the three power contacts

21

a

mounted to dual-mode vehicle

11

(FIG.

1

). Each contact

21

a

has a spring within it that biases it laterally outward into sliding contact with one of the conductors

68

.

Communication cable

65

is connected to a longitudinal communication array or strip

75

. Communication strip

75

might be an antenna for electromagnetic transmission to and reception of signals from communication device

21

b

. Alternately, strip

75

might be an optical transmitter and receiver for transmission to and reception of signals from communication device

21

b

. Communication strip

75

is secured by a clip to a bracket

77

on the interior of sidewall

47

.

As shown in

FIG. 5

, each of the rails

33

has one of the power bus bars

67

and one of the communication strips

75

. Also, each dual-mode vehicle

11

has electrical devices

21

on both sides. Consequently, when vehicle

11

locates closer to one rail

33

than the other, the closer rail will assure power and communication between the vehicle and the guidance system through one set of electrical devices

21

even though the electrical devices

21

on the other side may have lost communication and power.

Referring again to

FIG. 7

, each rail

33

has a shroud

79

mounted to it. Shroud

79

is preferably of a weather resistant material, such as stainless steel. It has an upper portion

81

on an inner side that extends downwardly and inwardly. In the embodiment shown, it is located at an angle of about 20% relative to vertical, although this angle can vary. Upper inner sidewall

81

has a free edge that terminates about midway between track

53

and upper flange

43

. Shroud

79

has a lower inner sidewall

83

that extends upward in a vertical plane. The upper free edge of lower inner sidewall

83

terminates somewhere below a midpoint between track

53

and upper flange

43

and also at an elevation lower than the free end of upper inner sidewall

81

. This results in a slot or gap

85

that faces downward and inward for receiving the inclined portion of axle

19

located between hub in

19

a

and central portion

19

b.

Shroud

79

also has a top wall

87

, an outer sidewall

89

, and a bottom wall

91

. Top wall

87

overlies upper flange

43

and joins upper inner sidewall

81

. Outer sidewall

89

is located in contact with the exterior side of channel member sidewall

47

. Bottom wall

91

locates below lower flange

85

and joins lower inner sidewall

83

.

Referring again to

FIG. 5

, the offset axle

19

and enclosed shrouds

79

allow a low center of mass

99

to prevent tipping on curves. Center of mass

99

is located at a distance

95

from support member

49

. Distance

95

is substantially less than track width

96

. In

FIG. 6

, a freight vehicle

97

for use on the guideway is shown. Freight vehicle

97

has a higher center of mass

99

than dual-mode vehicle

11

. However, even though higher, the distance

101

to support member

49

is considerably less than track width

96

. Freight vehicle

97

, similar to dual-mode vehicle

11

, has wheels

101

that are received within enclosed rails

33

.

Referring to

FIG. 12

, rails

33

are constructed to accommodate thermal expansion. This is handled by constructing enclosed rails

33

in sections

33

a

,

33

b

. Sections

33

a

,

33

b

have diagonal or beveled ends

105

a

,

105

b

. Ends

105

a

,

105

b

are an acute angle relative to the longitudinal axis of rail

33

. End

105

b

of rail

33

b

, is allowed to move laterally relative to the fixed end

105

a

of rail section

33

a

. Thermal expansion may cause the movable end

105

b

to slide relative to the fixed end

105

a

. A spring

107

urges movable end

105

b

of section

33

b

laterally into engagement with the fixed end

105

a

. Spring

107

is perpendicular to the longitudinal axis and is lodged against a stop plate

109

. Slotted mounting holes

111

in rail section

33

b

near end

105

b

limit the amount of lateral movement that end

105

b

can make.

In addition to dual-mode vehicles

11

(

FIG. 1

) and freight vehicles

97

that are meant only to run along the guideway, ferries

113

, as shown in

FIG. 14

, operate on the guideway. Each ferry

113

is a flat platform having axles

115

(

FIG. 15

) and wheels

117

. Axles

115

do not extend and retract because they are not meant to operate on conventional roadways. However, axles

115

do have offset ends and a lower central portion for extending through slot

85

. Ferry

113

has an electrical motor

119

, a braking system

121

and a controller

123

. Controller

123

controls the speed of motor

119

, preferably through a transmission, and also controls braking system

121

and a steering system. Signals from the guidance system will be received by controller

123

for operation along the guideway.

As shown in

FIG. 14

, ferry

113

has on its bed or frame one narrow channel or track

125

and one wider track

127

. Each track

125

,

127

is a channel member with upward facing flanges for receiving wheels

129

of a conventional motor vehicle

131

. The width of channel member

125

is slightly greater than the width of the largest expected tire of a conventional motor vehicle wheel

129

. There are a wide variety of widths of tires for wheels

129

, and track

125

will be set to accommodate the widest expected width. Track

127

is considerably wider than track

125

, such as two to three times as wide. This accommodates different distances between the wheels

129

on one side and the wheels

129

on the other side of a conventional motor vehicle

131

. Tracks

125

,

127

assure alignment of motor vehicle

131

in a longitudinal direction.

Referring again to

FIG. 5

, the guideway system has a guideway controller

133

that is connected to the signal cable

65

(

FIG. 7

) and in turn to communication strip

75

. Similarly, a power supply

135

is connected to power cable

63

(

FIG. 7

) and in turn to conductors

68

. Referring to

FIG. 10

, each conventional motor vehicle

131

will have a driver control unit

137

within the vehicle for communicating with guideway controller

133

. Driver control unit

137

may be stationarily installed in motor vehicle

131

or portable. Driver control unit

137

will communicate with a communication unit

139

located on ferry

113

, preferably by electro-optical or radio frequency signals. Communication unit

139

communicates with a ferry guideway communication unit

141

located on ferry

113

. Ferry guideway communication unit

141

communicates with guideway control system

133

via electromagnetic or optical signals through communication device

75

. This allows the driver of a conventional motor vehicle

131

to inform ferry

113

which station that the driver wishes to exit the automated guideway.

FIG. 11

illustrates a keypad

143

that may be a part of driver control unit

137

. Keypad

143

preferably has alpha numeric keys

145

to input destination codes and a display

147

. Furthermore, there may be function keys

149

for entering certain functions, such as entering or exiting. Keypad

143

may also be used in dual-mode vehicle

11

(

FIG. 1

)

Referring to

FIGS. 8 and 9

, conventional motor vehicles

131

may be driven onto a ferry

113

from a platform

151

. Platform

151

is located at an entrance to the guideway system, immediately in front the enclosed rails

33

(FIG.

3

). Platform

151

is located at an elevation above an entrance track

152

leading into the enclosed rails

33

. This distance is slightly greater than a distance from entrance track

152

to the tops of wheels

117

of ferry

113

, so that ferry

113

can roll on entrance track

152

under platform

151

. A ramp

153

is connected by a hinge to platform

151

for tilting between an upper ferry-loading position, and a lower dual-mode loading position. Ramp

153

has a free end

155

that will contact the bed of ferry

113

while motor vehicle

131

is being loaded as shown in FIG.

8

. As the ferry

133

moves away after loading, free end

155

will tilt downward to the dual-mode loading position shown in FIG.

9

. It will remain in this lower position unless another ferry

113

comes along, in which case the incoming ferry

113

will push the ramp

153

back upward to the upper position for receiving another conventional motor vehicle

131

.

If a dual-mode vehicle is to be loaded as shown in

FIG. 9

, ramp

153

must be in the lower position. Ramp

153

is preferably in the lower position normally, and in the upper position only while loading a conventional vehicle

131

onto a ferry

133

. In the lower position, free end

155

is lowered to the entrance track

152

leading to the enclosed rails

33

(FIG.

3

). Prior to leaving platform

151

, dual-mode vehicle

11

will move its wheels

17

to the expanded position for entering the enclosed rails

33

. Platform

151

is used for both conventional motor vehicles

131

and dual-mode vehicles

11

.

Referring to

FIG. 13

, an inspection station

157

is shown prior to an entrance gate

159

. Entrance gate

159

, when opened, allows a conventional motor vehicle

131

or a dual-mode vehicle

11

to pass to enter the guideway. Electronic video cameras

161

are placed on both sides of inspection station

157

. Video cameras

161

will record the external shape of motor vehicle

131

or of a dual mode vehicle

11

(FIG.

1

). The images will be processed by an image processor

163

. A computer

165

having a data base will compare the images to those in the data base to make sure that the vehicle

131

is capable of being driven onto the guideway. Computer

165

controls a gate controller

167

which opens and closes gate

159

.

Referring to

FIGS. 16-20

, a cargo container

169

is shown being carried on the guideway. Cargo container

169

is a conventional sea-land container such as carried on ships, railcars, and truck trailers. In this invention, cargo container

169

is carried on a ferry

171

, which is similar to motor vehicle ferry

113

(FIGS.

14

and

15

). As shown in

FIG. 17

, ferry

171

has a frame or bed

173

onto which container

169

is loaded. Ferry

171

is powered by an electrical motor

175

that is controlled by a controller

177

. Ferry

171

also has a brake system

179

controlled by controller

177

. Ferry

171

has at least two axles

181

, each having wheels

183

that roll on support members

49

within enclosed rails

33

. Axles

181

are offset for passing through slot

85

. Ferry

171

also has power and communication devices that receive power and control signals in the same manner as ferry

113

of FIG.

15

.

Latches

185

(

FIG. 19

) are mounted to frame

173

near each end for releasably securing cargo container

169

. Latches

185

may be of a variety of types, including types that secure sea-land containers to railcars or truck trailers. Also, end caps

187

are located at each end for reducing wind resistance. Each end cap

187

is connected to frame

173

by a hinge that allows movement between a storage position (FIG.

18

), a loading position (

FIG. 19

) and an operational position (FIG.

20

). Each end cap

187

has an inner side

189

, which may be flat or hollow, and an outer side

191

that is generally convex and aerodynamically contoured. The outer side

191

may be smoothly curved, as shown in

FIGS. 18-20

or it may be made up of several flat portions arranged in a generally convex shape as shown in FIG.

16

.

The storage position is employed while no container is located on ferry

171

. In this position, inner side

189

faces downward and lies against frame

173

. For loading, end caps

187

tilt outward to allow a crane (not shown) to lower container

169

onto frame

173

. In the operational position, end caps

187

locate upright, with inner side

189

abutting one of the ends of container

169

. A latch

193

may be employed on each end cap

187

to latch end caps

187

to container

169

in the operational position. In the operational position, convex sides

191

face in opposite directions, with one facing forward and the other rearward. The one facing forward serves to reduce wind resistance of the container

169

. The one facing rearward will do the same when ferry

171

is running in the opposite direction. Preferably, while in the upright operational position, the height of each end cap

187

is substantially the same as the height of container

169

.

In the operation with dual-mode vehicle

11

, as shown in

FIG. 1

, the driver will drive the vehicle to inspection station

157

(FIG.

13

). Its image will be recorded, compared to those in a database, then gate

159

will be opened. The operator drives vehicle

11

onto platform

151

and extends wheels

17

and power and communication devices

21

to the position shown in FIG.

2

. Ramp

153

will normally be in the lower position, allowing the dual-mode vehicle

11

to drive onto entrance track

152

leading into enclosed rails

33

(FIG.

3

). The operator then drives into the enclosed rails

33

, with wheels

17

driving on the support members

49

as illustrated in FIG.

3

.

Once in enclosed rails

33

, guideway controller

133

and power supply

135

will communicate with the electrical devices

21

of dual-mode vehicle

11

, as shown in FIG.

5

. Guideway controller

133

will signal vehicle controller

137

to disengage batteries

25

. Power will be supplied by the external power supply

135

, flowing through conductors

68

and

21

a

. (FIG.

7

). Signals will be provided either optically or electromagnetically through communication devices

75

,

21

b

. The driver will input his destination via keypad

143

. Guideway controller

133

will control the speed, braking and steering as dual-mode vehicle

11

proceeds to its destination. At the destination, dual-mode vehicle

11

will proceed out of the enclosed rails