APPENDIX A

NCHRP Synthesis 54-19 - Practices for Controlling Tunnel Leaks - DOT Survey

Dear State DOT Engineer,

TRB is preparing a synthesis on water leakage in highway tunnels. This is being done for NCHRP, under the sponsorship of AASHTO, in cooperation with FHWA.

The objective of this synthesis is to learn about the extent of the problem in state department of transportation (DOT) -owned highway tunnels, and the practices used by DOT tunnel owners to detect, identify, and control tunnel leaks. The information gained will be shared in a synthesis report at the conclusion of the study. The survey applies to tunnels and long enclosed roadways such as decks supporting parks and other infrastructure. If you do not have any of these structures, you only have one question to answer.

This survey is a primary means of gathering information for the synthesis. We would greatly appreciate a response from your agency. If you are not the appropriate person at your DOT to complete this questionnaire, please forward it to the correct person. Note that DOT survey responses will be shown in the published synthesis report. However, the identity of individuals will remain anonymous.

Please complete and submit the survey by March 24. We estimate the survey will take approximately 30 minutes to complete, although for some agencies less time will be required. If you have questions, please feel free to contact me.

Thank you for participating in the survey!

Martha Averso, P.E.

Principal Investigator

* Required

1. Name *

2. Position/Title *

3. Agency *

4. Phone Number *

5. Email Address *

Definitions

Curtain Grouting - a technique where holes are drilled trough the tunnel liner and chemical grout is pumped behind the liner at high pressure to eliminate the permeability of water directly behind and through the liner.

Cut and Cover Tunnel - this type of tunnel construction involves excavating from the ground surface down, constructing a box structure, and then backfilling to cover the tunnel. Cut and cover tunnels are often rectangular, but may be other shapes as well.

Deck-Over Structure - an enclosed roadway formed by a deck constructed to connect both sides of a depressed roadway, often supporting a plaza, park, buildings or other facilities.

Drill and Blast Tunnel - a tunnel that is excavated by drilling into the rock subgrade and blasting to facilitate removal of subgrade for installation of the tunnel liner. Drill and blast tunnels are often horseshoe shaped.

Ground Penetrating Radar - a geophysical probing of the liner and substrate using radar pulses to identify voids and irregularities.

Immersed Tube Tunnel - a tunnel that is constructed and floated into position in a body of water, then sunk into final position. Immersed tube tunnels are often rectangular but may be other shapes.

Jacked Tunnel - often used to cross under a roadway or railway, a jacked tunnel advances a tunnel liner hydraulically through the ground. Jacked tunnels are typically rectangular but may be circular or oval.

LiDAR - a method of obtaining a 3-dimensional representation of a surface using a laser and measuring the time for reflected light to return to the receiver.

Photogrammetry - a high resolution photography method used to obtain physical information, used as an aid in assessing the conditions of structures.

Sequential Excavation Method (SEM) Tunnel - a tunnel that is excavated sequentially in cross section, mining a portion of a ring at a time and reinforcing the exposed ground with shotcrete, until a complete ring is completed. An SEM tunnel is typically oblong or circular in shape.

Shield Driven/Bored Tunnel - a tunnel that is constructed using a tunnel shield/tunnel boring machine to excavate the ground for installation of the tunnel liner. Bored tunnels are typically circular in shape.

Substrate - the material or ground conditions behind the tunnel liner.

Thermography - also called thermal imaging, this method is used to evaluate temperature fluctuations to aid in identifying otherwise undetectable issues, such as the flow of water behind a tunnel liner.

6. Does your DOT have any tunnels or long enclosed roadways (>300 ft in length) such as deck structures over depressed roadways? *

Yes

No

If NO, skip to p. 25 of the survey.

Prevalence and Degree of Severity

7. In addition to your DOT’S tunnel inventory, does your DOT have tunnel-type structures with specialized systems for lighting, fire protection, or other systems? *

Yes

No

8. How many tunnels in your state’s tunnel inventory are owned by your DOT? *

9. How many of your DOT’S tunnels and tunnel-type structures have water infiltration or have experienced water infiltration in the past ten years? *

If none of your tunnels have experienced water Infiltration skip to p.25.

10. What problems does the water infiltration cause or has it caused in your DOT’S tunnels? (Check all that apply) *

Structural Deterioration

Functional System (and/or their Supports) Deterioration

Icicles

Slippery Roadways

Mineral deposits in drainage systems

None

Other

11. What techniques does your DOT use to manage these secondary challenges? *

12. How many tunnel-type structures exist within your state that are not owned by your DOT? *

13. How many of the non-DOT owned tunnel-type structures have experienced water infiltration issues? *

14. How many of your DOT’S tunnel-type structures currently have water infiltration or have experienced water infiltration in the past ten years? *

15. If GPR, thermography, LiDAR scan or photogrammetry were used, how effective were these non-destructive testing (NDT) methods in detecting leak locations? *

Very effective

Somewhat effective

Somewhat ineffective

Very ineffective

N/A

16. What is the primary source of water into your DOT’S tunnels or long enclosed roadways? (Check all that apply) *

Groundwater

Utility

Direct Surface Runoff

Other

17. What methods has your DOT used to identify the source of water infiltration? (Check all that apply) *

Investigating construction documents and details

Sampling and chemical testing of water infiltration

Dye testing of water infiltration

Other

18. What methods has your DOT used to identify the locations of water infiltration? (Check all that apply) *

Hands on visual inspections

GPR

Thermography

Photogrammetry

LiDAR scan

Other

Tunnel Types and Typical Leaks

For each series of questions below, provide responses for each tunnel which has experienced or is experiencing water infiltration. Information should be provided for three tunnels with the heaviest water infiltration.

19. Tunnel Name *

20. Tunnel shape and construction method (check the type where worst leakage occurs): *

Cut and cover rectangular box

Circular shield driven

Rectangular immersed tube

Horseshoe or oval drill and blast

Horseshoe or oval sequential excavation method

Unlined rock

Not certain

21. For your DOT’S tunnel(s) with the worst leakage, what is your level of concern/priority of repair with the current infiltration? *

1 - Top concern/needs remediation within two years

2 - High concern/remediation planned in next five years

3- Concerning but not high priority

4 - Not a concern nor top priority

22. What is the primary makeup of the substrate behind the tunnel liner? *

Rock

Soft Ground

Mixed conditions

Not certain

23. What are the primary sources of water infiltration in this tunnel? (Check all that apply) *

Groundwater

Utilities

Surface runoff

Unknown

Other

24. At what locations in the tunnel does water infiltration occur? (Check all that apply) *

Joints - either expansion, contraction or construction

Cracks

Transitions in structure types

Penetrations through the liner

Unknown

Other

25. What location contributes the heaviest leakage (considering volume and frequency) into the tunnel? *

Joints

Cracks

Transitions in structure types

Penetrations through the liner

Unknown

Other

26. Does your DOT have another tunnel to enter? *

Yes

No

27. Tunnel Name *

28. Tunnel shape and construction method (check the type where worst leakage occurs): *

Cut and cover rectangular box

Circular shield driven

Rectangular immersed tube

Horseshoe or oval drill and blast

Horseshoe or oval sequential excavation method

Unlined rock

Not certain

29. What is the primary makeup of the substrate behind the tunnel liner? *

Rock

Soft Ground

Mixed conditions - rock and soft ground

Not certain

30. What are the primary sources of water infiltration in this tunnel? (Check all that apply) *

Groundwater

Utilities

Surface runoff

Unknown

Other

31. At what locations in the tunnel does water infiltration occur? (Check all that apply) *

Joints - either expansion, contraction or construction

Cracks

Transitions in structure types

Penetrations through the liner

Unknown

Other

32. What location contributes the heaviest leakage (considering volume and frequency) into the tunnel? *

Joints

Cracks

Transitions in structure types

Penetrations through the liner

Unknown

Other

33. Does your DOT have another tunnel to enter? *

Yes

No

If NO, skip to Question 40

34. Tunnel Name *

35. Tunnel shape and construction method (check the type where worst leakage occurs): *

Rectangular box- Cut and Cover

Circular- shield driven

Rectangular or Circular- immersed tube

Horseshoe or oval - drill and blast

Rectangular or Circular - Jacked

Horseshoe or oval - Sequential Excavation Method

Unlined Rock

Not certain

36. What is the primary makeup of the substrate behind the tunnel liner? *

Rock

Soft Ground

Mixed conditions

Not certain

37. What is the primary source of water infiltration in this tunnel? (Check all that apply) *

Groundwater

Utilities

Surface runoff

Unknown

Other

38. At what locations in the tunnel does water infiltration occur? (Check all that apply) *

Joints - either expansion, contraction or construction

Cracks

Transitions in structure types

Penetrations through the liner

Unknown

Other

39. What location contributes the heaviest leakage (considering volume and frequency) into the tunnel? *

Joints

Cracks

Transitions in structure types

Penetrations through the liner

Unknown

Other

40. Which of the following methods has your DOT utilized to mitigate water infiltration in existing tunnels? (Check all that apply) *

Redirecting drainage with troughs, pipes, etc.

Injecting cracks with chemical grouts

Coatings applied on the inside of the liner

Replacing joint material and/or repairing/replacing gaskets

Installing a waterproofing membrane on the inside of the tunnel liner (umbrella)

Excavating and installing waterproofing membrane on the outside of the tunnel

Curtain grouting by drilling holes through the liner and injecting chemical grouts behind the liner

Other

41. Which of the following methods has been successful as a long term (>10 years) remediation for water infiltration? (Check all that apply) *

Redirecting drainage with troughs, pipes, etc.

Injecting cracks with chemical grouts

Coatings applied on the inside of the liner

Replacing joint material and/or repairing/replacing gaskets

Installing a waterproofing membrane on the inside of the tunnel liner (umbrella)

Excavating and installing waterproofing membrane on the outside of the tunnel

Curtain grouting by drilling holes through the liner and injecting chemical grouts behind the liner

Other

42. Which method has been most successful for your DOT in resolving leaks? *

Redirecting drainage with troughs, pipes, etc.

Injecting cracks with chemical grouts

Coatings applied on the inside of the liner

Replacing joint material and/or repairing/replacing gaskets

Installing a waterproofing membrane on the inside of the tunnel liner (umbrella)

Excavating and installing waterproofing membrane on the outside of the tunnel

Curtain grouting by drilling holes through the liner and injecting chemical grouts behind the liner

Other

43. What problems has your DOT experienced attempting to mitigate leakage in your tunnels? *

44. Has your DOT experienced any unintended consequences from the techniques used to remediate water infiltration?*

Yes

No

45. Describe the unintended consequence noted in the prior question.*

46. What information would be most valuable to your DOT as a tunnel owner with regard to water infiltration? *

47. What is the threshold for leakage at which your DOT would initiate water remediation? *

48. Does your DOT have specific acceptance criteria for leakage into a tunnel structure which is part of the new tunnel design criteria? *

Yes

No

Unknown

49. What is your DOT’S acceptance criteria for leakage in a new tunnel per the question above?

50. Does your DOT have specific criteria for a tunnel leakage remediation/rehabilitation project for acceptance of the leakage remediation work?

Yes

No

51. What is your DOT’S acceptance criteria for a tunnel leakage remediation/rehabilltation project per the previous question?

52. Would you be willing to participate in a brief interview to learn more about your experience with tunnel leakage and remediation? *

Yes

No

Thank You

THANK YOU FOR TAKING THE TIME TO PARTICIPATE IN THIS SURVEY. THE RESULTS WILL BE DOCUMENTED IN THE SYNTHESIS REPORT FOR NCHRP 54-19 PRACTICES FOR CONTROLLING TUNNEL LEAKS.

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