Preliminary Future Plan

Following the process outlined in the section below, pavement condition will be surveyed again starting in the fall of 2018, and the prioritization will be updated again to define next year’s plan. However, based on the current data, the table below presents the streets anticipated to be included in future years’ repaving contracts:

Pavement Management Plan Roadway Prioritization

The Engineering Department, with the aid of an outside consultant, maintains a database that defines several characteristics for every City-owned street. Three factors that strongly influence the prioritization of roads for repaving are:  “Functional Classification,” which ranks roadways from major arterial ways to residential side streets; “Average Daily Traffic,” and “Pavement Condition Index,” which describes the physical condition of the pavement. The City reassesses those factors on an annual basis, including conducting field surveys to update Pavement Condition. Those factors are then used in a formula to prioritize roads for inclusion in the annual improvement contracts.

The formula assigns the highest weight to Functional Class as it has been the City’s policy to prioritize main roads that receive the most use by the greatest number of travelers. Figure 1 provides the functional classification for each street in the database.  The factors used for Average Daily Traffic are also consistent with those used by the City for other transportation studies and are generally associated with the functional class categories. Pavement Condition Index is constantly degrading as roads experience wear over time. Consequently, the PCI is updated every year.

Only public rights-of-way are included in the database and are used for determining pavement priority. Private roads are not included in the database, and conditions are not assessed. Similarly, roads owned and controlled by Massachusetts DOT, including Alewife Brook Parkway, Mystic Avenue and McGrath Highway, are not included in the City’s Pavement Management Program.

Figure 1 - Functional Classification Map

2018 Data Update

Since the initial data was collected in 2014, the City’s consultant has conducted annual surveys to update the Pavement Condition Index (PCI). Our goal is to re-survey one-third of the City each year. Figure 2 provides the limits of the survey and when the survey occurred. Generally, the eastern side of Somerville was surveyed in the fall of 2016, and the western end of the city was surveyed in the fall of 2017. The central portions of Somerville last surveyed in 2015 will be surveyed again in the fall of 2018.

Figure 2 - Pavement Condition Index Survey Update

Based on this year’s survey, the average PCI in Somerville equals 58.8 on a scale of 0 to 100. This score is fairly typical of municipalities in Massachusetts. But like a grade of 59%, could be considered an F, which is also consistent with infrastructure grades throughout the country.

The PCI also informs the engineering decision on the best approach to repair the full-depth streets with very low scores will require full depth reconstruction or mill and pavement overlay. Streets with higher scores can be treated with crack sealing or pavement patching to extend their service life. Somerville has adopted the approach that it will simultaneously fund both types of projects so that degraded roads can be addressed at the same time pavement is cost-effectively managed to prevent slightly impacted roads from becoming worse. Figure 3 illustrates the inverse relationship between pavement aging and management cost.

Figure 3 - Age - Condition - Solution - Cost Relationship

Figure 4 illustrates the Pavement Condition Index (PCI) for each road in Somerville

Coordination with other Programs

Per Department of Public Works policy, once a road is resurfaced under the Pavement Management Program, that road remains on a moratorium for roadway opening for five years. Excavations in moratorium streets are discouraged, and when allowed require full pavement restoration a minimum of five feet on either side of any trenches with an overlay from curb-to-curb. Consistent with that policy for private services, and in the interest of intelligent management of City funds, areas targeted for other infrastructure improvements in the next five years are excluded from eligibility in the Pavement Management Program.

The Union Square Infrastructure Improvement Program identifies several improvements to the City’s combined sewer and drain system. The first project under that program, the Somerville Avenue Infrastructure and Streetscape Improvement Project, will begin construction in 2018. Two other projects, the Poplar Street Stormwater Pump Station Project and the Spring Hill Sewer Separation Project, will begin design in 2018. As that sewer-related capital investment program continues, several streets will be exempt from the Pavement Management Plan:

The City’s Capital Investment Plan for improving the water distribution system was initiated in 2013 and identifies several water mains for renewal or replacement. High-priority locations have been addressed, and generally the pace of the program is dependent upon funding. In 2017, the two programs were coordinated, for example deferring pavement of Properzi Way until the water work was completed in 2017, and prioritizing water work in Pearl Street so pavement work can be completed shortly after 2018. There are no specific Water CIP-related exclusions to include for the 2018 Pavement Management Program analysis.

The City is currently developing a master plan for Central Hill including the High School, City Hall and the Central Library. Similarly, the City is working with developers to identify additional developments in the Assembly Square area. Those planning efforts could result in recommended streetscape changes to improve multi-modal transportation. Consequently, the following segments are excluded from the Pavement Management Plan analysis:

Following gas main construction in 2015 and 2016, National Grid completed permanent trench patches in Broadway between McGrath Highway and Central Street. Per City policy, the warranty period on those repairs is two years. To maintain the benefit of that warrantee and avoid patches in newly paved roadway should the National Grid trenches develop an issue, the following segments are exempt from the Pavement Management Program through 2019:

The Pavement Management Plan will be reevaluated in the winter of 2018/2019 and an updated plan posted before the 2019 construction season begins.