PDH Online

Inspection of Highway and Rail Transit Tunnels

Quiz Questions

1.The shape of rail transit tunnels often varies along a given rail line. These shapes typically change at the transition between the station structure and the typical tunnel cross section. However, the change in shape may also occur between stations due to variations in ground conditions.
2. The ________________ tunnel is one in which no lining exists for the majority of the tunnel length.
Unlined rock
Ribbed Systems
3.Shotcrete is primarily used as a temporary application prior to a final liner being installed or as a local solution to instabilities in a rock tunnel. However, shotcrete can be used as a final lining.
4.The ____________________ can be used as a thin cover layer over the primary liner to provide a finished surface within the tunnel or to sandwich a waterproofing membrane. They can be reinforced or unreinforced. They can be designed as a non-structural finish element or as the main structural support for the tunnel.
Placed concrete linings
Segmental Linings
5. The invert of a tunnel is the slab on which the roadway or track bed is supported. There are two main methods for supporting the roadway or track bed; one is by placing the roadway or track bed directly on grade at the bottom of the tunnel structure, and the other is to span the roadway between sidewalls to provide space under the roadway for ventilation and utilities.
6. The oval tunnel with a single track and one safety walk is represented in ______________.
Figure 2.8
Figure 2.9
7.The horseshoe tunnel with a structural slab that provides space for an air plenum below is represented in ______________________.
Figure 2-11
Figure 2-12
8. The ___________ method is commonly used for older tunnels and is still used when it is determined cost effective or in difficult ground conditions.
Drill & Bast
Shield Driven
9.The method of jacking a large tunnel underneath certain obstructions (highways, buildings, rail lines, etc.) that prohibit the use of typical cut-and-cover techniques for shallow tunnels has been used successfully in recent years. This method is considered when the obstruction can be moved or temporarily disturbed.
10. ____________________are extremely fire resistant, economical, easily cleaned, and good reflectors of light due to the smooth, glazed exterior finish.
Porcelain-Enameled Metal Panels
Ceramic tiles
11.Epoxy coatings have been used on many tunnels during construction to reduce costs.
12.Figure 2.13 shows a typical profile of a ____________________________tunnel.
Naturally ventilated
Semi-Transverse Ventilated
13.The ___________________method is used primarily for longer tunnels that have large amounts of air that need to be replaced or for heavily traveled tunnels that produce high levels of contaminants.
Semi-Transverse Ventilation
Fully transverse Ventilation
14.There are two main types of axial fans—tube axial fans and vane axial fans. Both types move air parallel to the impellor shaft, but the difference between the two is the addition of guide vanes on one or both sides of the impellor for the vane axial fans.
15. _________________ are rolled steel plates or a rubberized material designed to protect the timber crosstie from localized damage under the rails by distributing the wheel loads over a larger area. They assist in holding the rails to gage, tilt the rails inward to help counteract the outward thrust of wheel loads, and provide a more desirable positioning of the wheel bearing area on the rail head.
Tie plates
Rail Joints
16.Plinth pads are concrete support pads or pedestals that are fastened directly to the concrete invert. These pads are placed at close intervals and permit the rail to span directly from one pad to another.
17. The typical third rail insulated anchor arm is represented in _________________.
Figure 2.19
Figure 2.20
18.The tunnel drainage system including sump pumps should be inspected to determine if the tunnel drains are clear of debris to permit water runoff to flow freely through the drains.
19.The maximum cross level on the outside rail of a curve may not be more than _______________on Track Classes 1 and 2 and 175 mm on Classes 3 through 5.
200 mm
300 mm
20.Timber crossties should be inspected to insure that they are not: broken through, split or otherwise impaired such that ballast can work through or spikes and rail fasteners cannot be held, so deteriorated that the tie plate or base of rail can move laterally 12 mm relative to the crosstie, or cut by the tie plate through more than 40 percent of the crosstie’s thickness.