May 6, 1999

Ms. Novina Wong

Clerk

City of Toronto

Toronto City Hall

Toronto, Ontario

M5H 2N2

Dear Ms. Wong:

At its meeting on Wednesday, May 5, 1999, the Commission considered the attached report entitled, "Standards For Structural Paving Rehabilitation Program."

The Commission received the above report for information which reaffirms the maintenance and replacement standards for the Commission's Structural Paving Rehabilitation Program, and directed that a copy be forwarded to the City Budget Committee in response to their request for the Toronto Transit Commission to report back prior to July 31, 1999 on the possibility of modifying its structural paving rehabilitation program on the basis of the standards applied by City Transportation in the rehabilitation of the arterial roads, including the projected change in expenditures for 2000-2003 resulting from such modifications.

The foregoing is foregoing is forwarded to the City Budget Committee for information.

Sincerely,

A.J. Chocorlan

Interim General Secretary

1-64

Attachment

TORONTO TRANSIT COMMISSION

REPORT NO. 15

MEETING DATE:May 5, 1999

SUBJECT: STANDARDS FOR STRUCTURAL

PAVING REHABILITATION PROGRAM

RECOMMENDATION

It is recommended that the Commission:

1.receive this report which reviews and reaffirms the maintenance and replacement standards for the Commission's Structural Paving Rehabilitation Program; and

2.forward this report to City of Toronto Budget Committee for information.

FUNDING

Not applicable.

BACKGROUND

At its meeting of March 2, 1999, City of Toronto Council adopted Clause 1 of Report No. 3 of the Strategic Policies and Priorities Committee which included, in part, approval of the Toronto Transit Commission's 1999-2003 Capital Works Program as recommended in a report dated January 14, 1999 from the Chair of the Budget Committee. Recommendation No. 5 of the Budget Committee's report required that:

"The TTC report to the Budget Committee prior to July 31, 1999 on the possibility of modifying its structural paving rehabilitation program on the basis of the standards applied by City Transportation in the rehabilitation of the arterial roads; and on the change to the projected expenditures for 2000-2003 (Project 332 Structural Paving Rehabilitation) resulting from the modifications;"

This report addresses that recommendation.

DISCUSSION

The Budget Committee's recommendation was based on the premise that:

"The repair program used by the TTC indicates a shorter life period and earlier first resurfacing than comparative standards used by City Transportation for the arterial roads".

The underlying assumption behind this statement is that TTC's "Structural Paving Rehabilitation" program is directly comparable to the City's "Arterial Road" program and that the same periodic maintenance and replacement standards should therefore apply. Following discussions between TTC and City staff it is clear that such a comparison is in fact invalid as the design features, in-service conditions and performance expectations for these two programs are entirely different. The City's arterial roadways consist generally of an asphalt wearing surface on an unreinforced concrete base on a granular sub-base whereas the TTC's structural pavements are those attached directly to elevated structural slabs over tunnels, subway stations or bridges where steel reinforcing, complex expansion joints and waterproofing membranes are normal components of the work and the consequences of shrinkage cracking, salt penetration, leakage and deterioration are of much greater significance.

If comparisons must be made it would be much more appropriate to compare the TTC's structural paving program with City standards for bridge decks which are subject to similar service conditions and provide for resurfacing at 15 to 20 years, asphalt and waterproofing membrane replacement at 25-30 years and slab replacement at 35-50 years depending on the type of concrete used in the original structure. This compares favourably with the TTC structural pavement standards of resurfacing at 15 years, replacement of asphalt and waterproofing membrane at 30 years and full slab replacement at 45 to 50 years as outlined in TTC's approved Capital Program submission. The referred standards are summarized in the attached table for information.

Based on this review, it is concluded that modifications to TTC's structural paving program standards are neither appropriate nor warranted and there should be no change in the projected annual expenditures detailed in the approved 2000-2003 Capital Program related to standards for this work.

JUSTIFICATION

The maintenance and replacement standards currently used for TTC's Structural Paving Program are considered appropriate for the type of work and service expectations involved.

- - - - - - - - - - - -

April 15, 1999

80-31-30

601387

APPENDIX 'A'

SERVICE STANDARD COMPARISONS

 

		Service Life (Years)
Item	City Bridge Decks	TTC Structural Paving (elevated slabs)	City Arterial Roads (On-Grade Paving)
Arterial Roadways - First resurfacing - Second resurfacing - Replacement			23-26 40 60
Elevated Structural Slabs - Resurfacing - Asphalt/membrane replacement - Slab replacement	15-20 25-30 *35-40	15 30 45-50

 (* For normal 30 MPa concrete; extends to 45-50 for silica fume concrete)

STAFF SUMMARY SHEET

601387