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Plan Development Process

Transportation deficiencies were identified for congestion, safety, bridges, transit, pavement and non-motorized facilities using the methods detailed below. Financial forecasts were developed at the regional level by SEMCOG staff and provided to WATS as noted above. WATS staff then worked with the operating agencies using the deficiencies and the financial forecasts to develop proposed improvements. The proposed improvements were then divided into funded and unfunded categories within the limitations of the financial forecasts. The list of funded improvements was amended prior to final approval to reflect changes made based on the public comments.

A map of the funded improvements is included in this report on page 49. Charts depicting the 2030 planned improvements by number of improvements and cost of improvements are provided on pages 104 and 105. The list of funded improvements begins on page 56. The unfunded improvements are provided in Appendix B. Although a list of unfunded improvements has been included, it is not comprehensive because some of the agencies did not provide unfunded improvements even though needed improvements were identified by the deficiencies and through public comment. A description of how each type of the plan deficiencies was identified is included below.

Congestion Deficiencies

The primary purpose the WATS travel model serves for the development of the Long Range Plan is the designation of congestion deficiencies. For the 2030 Plan, WATS staff used a new computer model operating in TransCAD GIS software. The new model is a full mode choice model with an operating transit route system, the highway (includes all federally funded roads) network and a non-motorized component. For more detail on the model see the "New TransCAD mode choice model with transit route system" section in Appendix C.

The WATS model is used to project future travel on the model network using socio-economic data (households, employment, land use, etc) and equations derived from the 1994 regional household travel survey data for each time period. The Southeast Michigan Council of Governments (SEMCOG) using the local communities master plans, zoning plans and the sewer service areas, completes the socio-economic projections. WATS staff allocates these projections to the County traffic analysis zones (TAZ). The model is calibrated in the base year so that it closely matches the transportation system on an average day. This allows us to show and project congestion throughout the system into the future.

The model was run for each five-year period using the socio-economic data. Congestion deficiencies were identified for each of those time periods. Once the future trips were assigned to the countywide network and transit route system, the deficient facilities were defined using a volume to capacity (V/C) ratio. Freeway segments were designated as deficient if the volume shown in the model reaches 100% of the road's capacity. A table that takes into account the number of lanes, area type and the National Functional Classification (NFC) of the link determines capacity. Because access to freeways is limited to entrance and exit ramps, delay is not apparent until the capacity of the road is reached. Non-freeway roads have stop signs, traffic lights and multiple driveways and because of these, congestion is reached and delays occur before the road has actually reached its capacity. For this reason WATS defined a non-freeway road as congested when it reached 80% of its capacity.

This congestion designation was calculated for each time period and the data was displayed using the time period during which the segment first becomes deficient. It was assumed that the segment would be deficient in future years unless some improvement is made, i.e. widening of the facility or improvements to alternatives such as increases in transit service or the construction of a park and ride lot.

Analysis was completed on the transportation system examining the deficiencies by the national functional classification as well as by community. Table 8 shows that nearly 34 percent of the total system of collectors or above are congestion deficient. Of the deficient miles, over 65 percent of the total system is already deficient in 2005.
The majority of the deficient miles occur on the freeway system that includes I-94, US-23 and M-14 with 56.31 percent of miles with traffic at or above the capacity. The principal arterials such as Washtenaw, Ellsworth, Jackson and Plymouth and the minor arterials such as M-52, Ford Road, Dexter-Ann Arbor and Ann Arbor-Saline follow close behind at 50.46 and 42.22 percent miles congested respectively. Congestion deficiencies by community are provided in Table 9.

Map 1 ~ 2030 Congestion Deficiencies by Year First Deficient

Safety Deficiencies

The Southeast Michigan Council of Governments provided WATS with intersection crash data for the years 1997-2001. Due to problems with the way the State of Michigan reported the crash data, only the data from 1997-1999 was useable because approximately thirty percent of the 2000 and 2001 crashes were not located. WATS chose the 1997-1999 three-year period to be the sample of crashes for the identification of intersection crash deficiencies because it was the most recent three-year period with nearly 100% of the crashes located.

A selection was made of all intersections within the Washtenaw County that averaged two or more crashes between 1997-1999. A total of 856 intersections in Washtenaw County averaged two or more crashes between 1997-1999. For this analysis any crash within a 150 feet of an intersection was classified as an intersection crash.

At the time the 2030 Plan was being developed data on crashes occurring on a street segment (more than 150 feet from an intersection) was not available in a Geographic Information System (GIS) format. As a result, staff was not able to perform an analysis on segment crashes as in the 2025 Plan.

To effectively evaluate the intersections, WATS staff used a combination of crash frequency and crash rate to offset the over representation of low volume locations in the crash rate analysis and the over representation of high volume locations in the frequency data.

Crash rate that normalizes the crash data by the number of vehicles entering an intersection. WATS used the following crash rate formula:

Traffic count data for vehicles entering the intersections was available for only 285 of the 856 intersections that had at least 6 crashes over the three-year study period. As a variable in the crash rate formula, this data is critical to calculate deficiencies based on exposure. The intersection deficiencies were ranked by adding the rankings of crash frequency and crash rate together and giving the lowest total number the raining of 1 (the intersection needing the most examination), the next lowest 2 and so on. Using this process, staff was able to rank all 285 intersections based on both frequency and rate.

This combined ranking identified the intersection which ranked highest using both frequency and rate as the intersection of Hogback/Carpenter and Washtenaw (M-17). Between 1997 and 1999, 172 crashes occurred within 150 feet of this intersection and based on the number of vehicles entering the intersection on a given day the crash rate was 3.9. This is to say that there are 3.9 crashes for every 1,000,000 vehicles that enter the intersection. Table 10 lists the 25 intersections with the highest combined ranking in Washtenaw County. All of the ranked intersections are shown on Map 2 on page 33.

It is important to remember that these intersections only represent those for which WATS had traffic counts for all entering vehicles. A complete list of crashes is available in the 1997-1999 Crash Report.

Future Improvements

In 2003, the WATS Policy Committee approved the use of funds to purchase scanning equipment capable of reading UD-10 crash reports. WATS is now scanning data on crashes occurring within the County and works with local law enforcement agencies to insure the reliability of the data. Initiated in 2004 data, process will allow for nearly 100% of the crashes occurring within the County to be located to a unique intersection or road segment. With a complete data set, WATS will again be able to perform a more in-depth analysis of both intersection and segment crash deficiencies.

Map 2 ~ Safety Deficiencies

Bridge Deficiencies

Working in collaboration with the Southeast Michigan Council of Governments (SEMCOG) and the Michigan Department of Transportation (MDOT), WATS staff was able to gather bridge data from the state database for Washtenaw County. Bridge facilities are inventoried biennially by local road agencies and the data is entered into the State's Michigan Structure Inventory and Appraisal (MSIA) database. Facilities are identified as functionally obsolete or structurally deficient. A functionally obsolete bridge is defined as in need of repair or upgrade because it no longer meets the transportation system's needs. An example of a functionally obsolete bridge would be one that needs the bridge widened to match the adjacent road or may be out of date by current construction standards. A structurally deficient bridge is defined as one in need of extensive repair or replacement. An example of a structurally deficient bridge would be a bridge with weight restrictions such as the Main St. Bridge in Dexter over Mill Creek. Bridge's that were both functionally obsolete and structurally deficient were classified as structurally deficient.

As in past plans the 2030 Long Range Transportation Plan identifies facilities that are currently structurally deficient or functionally obsolete. There are a total of 122 bridges that are currently deficient in Washtenaw County. The deficient bridges are shown on Map 3 on page 36. This map includes 66 bridges classified as functionally obsolete and 56 classified as structurally deficient. Of these, approximately 13 are on the Critical Bridge "on-system" and "off-system" lists and eligible for federal funding. These bridges are listed in Tables 11 and 12 respectively. Eleven bridges are "on-system" or located on major roads classified as part of the federal aid network. While two bridges are "off-system", these are located on local roads and not a component of the federal aid network. Bridges found on the off-system Critical Bridge list typically experience lower traffic volumes.

In 2004, the top three bridges from the "on-system" and the first ten bridges from the "off-system" Critical Bridge lists were awarded funding. On-system bridges will receive $1,631,000 while off-system bridges will receive $4,983,750. The 2004 Critical Bridge awards did not fund improvements on any bridges in Washtenaw County.

Future Improvements

The selection of bridges for bridge funding is currently done at the State level and only complete replacement of bridges is funded. The State is currently developing a new program that will split the existing program into two parts with replacement and rehabilitation components. The program also currently has a problem with a backlog of "funded" bridges that are not being designed and constructed. The new process also recommends bridge selection on a regional basis. If this process is implemented, there will be a need to refine the bridge deficiencies and improve the bridge prioritization process. This would require more information on the deficiencies and recommended improvements for each.

Map 3 ~ 2030 Bridge Deficiencies

Transit Deficiencies

Transit deficiencies analyzed using three different methods for this plan. WATS staff completed an analysis of the transit capital needs using a federally recommended bus replacement schedule, a level of service (LOS) transit analysis and a GIS analysis using census data to locate areas with transit dependent households located outside the existing fixed route area.

The federal bus replacement schedule provides the Ann Arbor Transportation Authority (AATA) with a life expectancy for each bus in its fleet according to age and size. The replacement schedule gives a 12-year life span to large buses, a seven-year lifespan to medium size buses and five years for small buses. AATA becomes eligible for funding to replace buses in its fleet according to the age of the bus. Chart 1 below shows the anticipated bus replacements for AATA throughout the life of the 2030 Plan.

AATA is scheduled to replace a total of 221 buses over the 25 years of the plan; 142 large, 24 medium and 55 small.

For the second analysis, SEMCOG provided WATS with the process for evaluating transit LOS based on the Transit Capacity Service Quality Manual (TCSQM). Using the guidelines in the TCSQM, WATS determined LOS in two ways, as both a composite rating, which used Headway, hours of service and weekend service and also by peak period headway only. Chart 2 illustrates AATA and University of Michigan (UofM) LOS based on a composite ranking.

The composite ranking reveals that AATA's service averages a LOS of D with some routes operating as LOS E. It is important to note that the demand does not exist in the AATA service area to warrant a LOS higher than D. The AATA routes also charge a fare of $1.00 although tokens and monthly passes are available at a reduced rate. UofM has routes operating at LOS of B, C and D, this is due to the fact that students, faculty and staff use UofM service and there is no fare. Transit routes operating at a higher LOS reflect the higher demand.

Chart 3 on page 38 depicts the UofM and AATA LOS based only on peak hour headway. Again UofM has higher demand and fares are subsidized while AATA still provides service averaging an LOS D.

In the third transit analysis, WATS staff also identified areas with the largest number of households without access to an automobile using census data. WATS used TransCad GIS to determine the number of households without access to automobiles by traffic analysis zones (TAZ).

This analysis revealed several "hot spots" or areas that had significantly higher numbers of households without access to automobiles. Northfield Township, Manchester Township and the City of Milan all have relatively high numbers of households without access to automobiles. The data does however give local transit service providers an idea of the areas that have the highest concentrations of households without access automobiles.

This data maybe somewhat unreliable because it is a census long form sample question that is not given to every household. The U.S. Census Bureau uses expansion factors to apply the results from the long form questions across a geographic area. These geographic areas are census block groups. Due to confidentiality requirements, block groups are the smallest disaggregation available for the households without access to a personal vehicle. The expansion factor used by the Census Bureau and applying the data to the WATS TAZ layer through an overlay process makes the data somewhat less reliable.

Future Improvements

In the future, WATS hopes to expand on these transit analyses using the WATS model. Staff will use the model to test alternatives including the effect of a park and ride lot on the congestion streets. Staff will also use the model to estimate the increase in ridership as a result of a new route or the extension of an existing route. While the effects may be minimal, the WATS model is also capable of modeling change in ridership based on fare changes or changes in the parking costs through the mode choice portion of the model.

Map 4 ~ Transit Deficiencies

Pavement Deficiencies

Roads and highways are under the jurisdiction of the MDOT, the Washtenaw County Road Commission (WCRC), cities and villages. For Act 51, the cities and villages certify the higher classified roads as major while the Road Commission certify them as primary. The cities, villages and the road commission all use the local road classification. The MDOT has jurisdiction over the trunklines such as I-94, M-14 and US-23 as well as the business routes and highways such as M-52, BL-94/Washtenaw and M-153/Ford Road. A break down of the mileage for these classifications is listed in Table 13.

Local agencies responsible for maintaining roads within Washtenaw County provided the Agency with their individual pavement ratings or projected paving projects. Currently there is no single pavement evaluation program that is used throughout Washtenaw County; two commonly used are MicroPAVER and RoadSoft. The City of Ann Arbor provided information from their MicroPAVER program, the Washtenaw County Road Commission provided information from their RoadSoft GIS and the remaining agencies provided a variety of lists and maps of pavement deficiencies as identified by consultants. We were not able to obtain rating information from the MDOT and as a result our evaluation does not include deficiencies for MDOT controlled routes. Methods of evaluating pavement conditions vary between these programs; however, all provide a rating scheme that can be standardized to the following categories: very poor, poor, fair, good, very good, and excellent. The pavement is considered deficient when it can no longer service the traffic it was designed to carry. The categories of very poor, poor, fair and good were considered deficient now or in the future.

Information provided by the agencies was compiled with the ratings compiled into poor, fair and good condition. Road segments that received a very good or excellent rating were new roads or those that had been recently reconstructed. For this analysis the assumption that these roads would receive regular maintenance was made and as a result would not become deficient within the 30-year life of this plan. For the more detailed segment analysis, where sections of roads were subdivided and rated differently, we calculated the length of road in each rating category. If one third or greater of the segment fell within the lower rating, the entire section of the road was given that rating. Agencies not included in the ranking did not report deficiencies.

Table 14 summarizes the total pavement deficient miles for those agencies that provided WATS with pavement ratings. This does not include MDOT deficiencies for roadways under their jurisdiction. Roadways that are currently rated poor are considered deficient in 2005, those rated fair are considered deficient in 2015 and those rated good are considered deficient in 2030.

Future Improvements

MDOT, with the cooperation of all the Counties, has begun a process that will uniformly evaluate roadways throughout the State. Roadways are evaluated using a visual inspection and given a PASER rating. The Asset Management Program incorporates these ratings into the RoadSoft program for database management and further analysis. This program was initiated in 2003 and a 3-person team consisting of MDOT, WATS and Road Commission personnel inspected all the Washtenaw County roads, eligible for federal funds. Similar inspections were held in all 83 Michigan Counties. The Cities were given the option to have staff participate when evaluations were being performed within their jurisdiction. During this first phase, the cities within Washtenaw County chose not to participate.

The Asset Management Program is an ongoing program. In