City of Lawrence

Public Works Department

MEMORANDUM

 

TO:              David L. Corliss

          City Manager

FROM:          Steven M. Lashley, P.E.

                   Project Engineer – Infrastructure Management

DATE:           November 3, 2009

RE:               Pavement Maintenance Program Update – Cycle Two Status Report

& 2010 Street Maintenance Program

 

 

Introduction

In early October, 2009, the second cycle of the street pavement condition inventory for the Pavement Management Program (PMP) was completed.  The full cycle involved the analysis and collection of physical inventory on every rateable street segment within the City of Lawrence, which ended the four-year period since the completion of the first cycle in late October of 2005.  In Cycle One (C1), a total of 299 center-line miles of streets were rated (1,922 street segments) and in Cycle Two (C2), due to annexations and new construction, a total of 319.5 center-line miles of streets were rated (2,047 street segments).  The PMP provides Public Works with a management tool to maintain an inventory of street pavement, their respective condition and maintenance work history, and the ability to identify budget needs and impacts associated with pavement preservation strategies and asset management.  This tool has been successfully utilized in the contracted maintenance years 2006 through 2009 and has provided the basis for the Proposed 2010 Street Maintenance Program.

Impact of Program & Comparative Pavement Analysis

The impact and effectiveness of the PMP can be estimated based on several factors determined through pavement analysis.  One measure is the change in the average Pavement Condition Index (PCI).  Another measure is the change in the rate of deterioration of the pavements.  The overall progress of the program may also be reflected by the change in the percentage of streets with PCIs in the “unacceptable” range.  Direct impacts to these types of measures include preventative maintenance activities such as crack/joint sealing and pavement surface seals, minor or major rehabilitations such as full depth pavement repairs and milling and overlay, and the reconstruction of entire pavement segments.  Other impacts that affect overall pavement conditions and data analysis include the accumulation of additional City streets through new construction and annexations.  The following comparative pavement analysis was based on data collected from October of 2005 and ending in October of 2009, which was performed concurrently throughout the construction and maintenance period beginning in 2006 and ending in 2009.

 

Average PCI

The overall average PCI for Lawrence streets was 69.0 for C1 and 70.28 for C2 based on street center-line length and a “0-100” rating scale.  We saw an overall positive PCI increase of 1.86% from C1 to C2.  A score of “0” represents a pavement with all distresses present at their highest severity and extent levels.  A street pavement segment with a score of “100” represents a pavement segment that has no visible distresses.  The average PCI comparison between C1 and C2 for Brick, Composite, Flexible, and Rigid streets, respectively, was 38.1/42.9, 62.2/66.8, 75.4/74.0, and 58.7/61.0 (See Figure 1).  The average PCI comparison between C1 and C2 for Arterial, Collector, and Residential streets, respectively, is 68.7/71.2, 72.3/72.5, and 68.3/69.6 (See Figure 2).  The general trend from C1 to C2 displays sustainability of current pavement condition levels and a slight upward movement of pavement condition in most categories.  The slight decline in average PCI on flexible pavement types could be attributed to a negative impact of flexible arterial pavement deterioration (See “Deterioration Rates”, Page 3).  Please note that curb and gutter conditions on the pavement segments surveyed does not impact the PCI for the street.

 

 

 

Curb and gutter (both sides), if it exists along the various pavement segments surveyed, has a separate and simplified rating scale designation of Poor, Fair, and Good.  The PMP reports, for C1 and C2 pavement segments respectively, 79.5/52.4 miles of curb and gutter are in Poor condition, 174.9/172.6 miles in Fair condition, 291.2/359.4 miles in Good condition, and 52.4/53.3 miles of non-existing curb and gutter (See Figure 3).  Overall, the amount of curb and gutter in Good condition has increased significantly by approximately 68 miles while there was a decline in the combined Poor to Fair condition curb by 29 miles.

 

 

 

Deterioration Rates

Please see Table 1 for a comparison of the deterioration rates calculated from C1 and C2.  Updated C2 deterioration rates were calculated based on the change in PCI for each comparable street segment from C1.  A significant portion, 86%, of the C2 segments was comparable.  Variations in pavement segment designations limit comparisons based on factors such as construction limit changes from C1 and C2 and new street segments that did not exist prior to C2.  The data was analyzed and grouped by pavement type and street classification as shown.  The results in the data table reflect a significant slowdown in overall deterioration of streets in nearly all categories with some positive gain.  This is a clear indicator of positive movement towards pavement maintenance sustainability.  It is apparent that some of the strongest gain on deterioration rates was on composite pavement types and due to the increased amount of overall preventative and rehabilitation maintenance activities on composite pavements.  Please note that a “-” indicates a decline in pavement condition and a “+” indicates an incline in pavement condition.

 

 

 

TABLE 1

Pavement Type

Street Classification

C1 – Deterioration Rate

C2- Deterioration Rate

Flexible (Asphalt)

w/ No Past Overlay

Arterial

-2.40

-2.60

Collector

-2.38

-1.84

Residential

-2.40

-1.18

Flexible (Asphalt)

w/ Past Overlay

Arterial

-6.42

-2.66

Collector

-5.60

-1.00

Residential

-5.27

+2.28

Composite (Asphalt over Concrete/Brick)

Arterial

-8.70

+1.58

Collector

-5.62

+0.86

Residential

-3.84

+0.72

Rigid (Concrete)

Arterial

-1.97

-0.93

Collector

-1.50

-0.21

Residential

-1.41

-0.35

 

“Unacceptable” Streets

The initial goal of the Pavement Maintenance Program was to prevent further deterioration of streets beyond the point at which preventative maintenance measures would no longer be cost effective.  The critical point has been identified as a PCI of 65 for Arterials, 60 for Collectors, and 55 for Residential streets.  Streets with PCIs below those values have been termed “unacceptable.”  Cycle 1 indicated that 31.5% of streets in the City fell into the “unacceptable” range and would generally require a milling and overlay as a proper treatment and in some cases reconstruction is needed.  Cycle 2 indicated that 29.8% of the city street pavements were “unacceptable.”  The frequency graph (See Figure 4) displays the percentages of all rated streets that fall within various PCI condition ranges per cycle.  A positive shift in condition frequencies can be seen from C1 to C2.  For example, there is a cumulative total of 3% more streets above a PCI of 60 (>60-100) in C2 (69.3%) than C1 (66.3%).

 

 

Evaluation of Results and Analysis Summary

The comparative analysis has provided a significant insight into the impacts of street maintenance performed over the last four years and indicate that the maintenance programs are slowing and in some cases reversing the deterioration rates along with an overall PCI increase.  The positive impacts to the street network are a direct result of many factors including the following summation of maintenance and reconstruction dollars spent in the last four years (See Table 2).

 

TABLE 2

Actual Dollars (Approx.)

Description

Contracted Street Maintenance Program (2006 through 2009)

$16.05 million

Crack Sealing – 443.0 lane-miles

Microsurfacing – 69.0 lane-miles

Milling & Overlay – 87.3 lane-miles

Curb & Gutter – Approx. 31.4 miles

Public Works Internal Street Maintenance

$1.1 million

Asphaltic & Concrete

Material Costs Only

W 6th St - Folks Rd to K-10

$15 milllion

Reconstruction, Widening, Mill & Overlay – 2006 Completion

Kasold Dr – Bob Billings Pkwy to W 22nd St

$5.39 million

 Concrete Reconstruction – 2007 Completion

Ohio St – W 6th St to

W 8th St

$680,000

Brick Reconstruction – 2008 Completion

W 19th St – Tennessee St to Alabama St

$1.0 million

Reconstruction, Widening, Mill & Overlay – 2008 Completion

 

 

Results of the comparative rating analysis have displayed a positive move towards overall sustainability.  I believe that the increasingly more positive movement from C1 to C2 is due to the overall improved balance between contracted maintenance activities that include preventative maintenance and minor/major rehabliltation work, daily internal street maintenance activities including small projects, and the capital improvement and special project reconstructions.  This maintenance diversity has been summarized in Public Works “Guide to Street Maintenance in Lawrenece” public educational pamphlet that was produced and became available earlier this year (attached).  As an example to display the expansive use of the various maintenance applications, please see the attached map entitled “2006-2009 Comprehensive Street Maintenance Programs Map.”

 

One reason that the overall PCI increased from C1 to C2 while most deterioration rates still remain negative was that the overall PCI has been directly impacted and partially saturated by new street construction projects and annexation of other streets in an “acceptable” condition.  These types of streets have not impacted deterioration rates since they did not exist prior to the completion of C1.  For example, if new street construction were to dramatically increase, then overall PCI condition reporting may reflect an overall upswing of condition scores even though streets in the “unacceptable” condition have not been addressed and continue to affect overall deterioration rates from one cycle to the next.  This would be a situation where deferred maintenance continues and results in continual negative deterioration of some pavement segments resulting in a “backlog” of City streets.

The highest deterioration rates continue to exist on Arterial streets in most categories.  Arterial streets demand a higher level of service due to the significantly higher amount of daily truck traffic volumes.  It is apparent by review of work history that the repetition of milling and overlaying is becoming more frequent over the years and that the City has utilized the pavement beyond the expected design life cycle.  Several arterial pavement structures, such as Kasold Dr south of Clinton Pkwy and Bob Billings Pkwy from Iowa St to Kasold Dr, fit this profile and need to be included in a replacement/reconstruction program such as through the CIP.

 

Please note that new street construction costs and the valuations of acquired street assets in subdivisions, such as from street benefit district projects, and the expanded street network associated with street annexations, have not been included in this report.  These additional assets affect future maintenance funding needs.  If it is the goal of the City of Lawrence to sustain streets in the current overall conditions, funding must be increased over the current contracted maintenance funding levels.  This increase must be accompanied by the continuation of Capital Improvement and other special projects involving reconstruction of streets in “unacceptable” condition.  The street network has grown with new development and annexations so street maintenance funds are being spread more thin each year to maintain the whole.

 

2010 Street Maintenance Program

In August of 2009, the City Commission approved approximately $5.2 million to be utilized for the 2010 Street Maintenance Program.  The pie chart below gives a breakdown of the various funding sources.  The “Proposed 2010 Comprehensive Street Maintenance Program” map is attached to this document.  The map includes streets identified for crack sealing, microsurfacing, mill and overlay/curb and gutter, internal street maintenance project areas that include concrete rehabilitation work, and other project locations such as the KLINK and Sales Tax projects.  A further breakdown of where maintenance dollars are planned to be spent are included for each type of maintenance project in the map legend.

 

 

Kasold Dr from Trail Rd to Peterson Rd has been selected as the “2010 Sales Tax Project.”  Some details of the proposed work include partial to full depth asphalt pavement replacement, some curb and gutter removal and replacement, sidewalk installment along the east side of Kasold, consideration for the installment of pavement striping for shared bike lane use similar to Naismith Dr from 18th St to 23rd St, and the coordination with Parks and Recreation Dept to remove the existing asphalt median and replace with landscaping.  As in past years, internal street maintenance will also be involved with collaborative work efforts with some of the contracted projects such as intermittent curb replacement on a mill and overlay only project.  Similar coordinated efforts with Utilities Dept are expected to occur.  For example, during the 2009 9th St Sales Tax Project, Public Works and Utilities Dept coordinated work efforts to rehabilitate waterlines while the 9th St and Avalon Rd intersection was rebuilt.

 

The proposed 2010 program map has been sent out for preliminary review to other departments, local utilities, consultants, and other local authorities for determination of potential impacts, conflicts, and coordinated work efforts including scheduling.

 

 

Action Request

-       Approve 2010 Street Maintenance Program.

 

 

Respectfully submitted,

 

Steven M. Lashley, P.E.

Project Engineer – Infrastructure Management

Department of Public Works

 

 

Attachments: Public Works Pamphlet, 2006-2009 Map, 2010 Map