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Deficiency Analysis

Deficiency Analysis

The MPO developed the Deficiency Analysis for the 2040 Long Range Transportation Plan. See the Web page for maps and tables. The following link is a presentation on the Deficiency Analysis. This Web page provides the detailed tables and maps that comprise the Deficiency Analysis and presents the Socioeconomic Data (SE Data) used to generate the analysis.

Congestion Maps

The congestion maps estimate the level of congestion in the year 2040 if no additional transportation projects are implemented. This is often called the No Build Scenario. In this case, the travel demand model puts the trip demand for the 2040 population and 2040 employment on to the current transportation network that might also have a few additional approved projects (e.g., East End Connector) that are close to beginning construction. The attached maps depict the level of congestion by dividing the traffic volume by the road capacity. So, if the road has 8,000 vehicle trips per hour and the road capacity is 10,000 vehicles; the V/C (volume to capacity value) will be 0.80. Note that the MPO's travel demand model uses a Level of Service (LOS) of "E," or the V/C = 1.0. Most motorists would experience LOS E as highly congested and the overall travel delay would be great especially in urban areas and those areas with intersections and driveways. Thus, most users of these maps will want to consider a roadway as congested and needing improvements as the V/C approaches 0.85, which is an approximation for the threshold for LOS D.

Afternoon Peak

The congestion maps below show the V/C for both directions of each roadway for the afternoon peak period (3:30pm to 7:30pm). Keep in mind that these congestion levels are an average of the four-hour afternoon period. Thus, the actual congestion at a specific time or during a specific hour in the afternoon might be better or worse than that shown on these maps. For example, the congestion level at 5:30pm (i.e., the peak of the afternoon peak) will likely be worse on most roads than that shown on these maps.

Daily

The congestion maps below show the daily V/C for both directions of each roadway. These values are an average for a day and use the "no build" scenario, which includes the 2040 population and employment using the current transportation network.

Isochrone Maps

An isochrone map shows lines that connect the points that have the same travel time from a specified point. The isochrone maps below show the travel time to key destinations in the Triangle region in fifteen minute increments. The destinations for the most part are in the downtowns.

Performance Measures

The Performance Measures are a broad set of calculations that provide an indicator of the mobility, trip volume, mode choice and congestion in the overall transportation system. The measures are not specific to a travel corridor or transportation project but are useful for broad comparisons of different transportation system alternatives. The first table below compares the 2010, no build and 2035 LRTP transportation systems for the DCHC MPO. The remaining three tables provide a breakdown of these same transportation systems by MPO and county.

SE Data

The DCHC MPO forecasts Socioeconomic Data (SE Data; such as dwelling units, population and employment) to the year 2040 and uses the data as a key input into the Triangle Regional Model (TRM -- the regional travel demand model). The TRM is a principal tool for identifying the future transportation deficiencies in our area and proposing transportation projects and improvements to address those deficiencies. This model is used for long range plans, major transit and transportation studies and transportation project environmental analyses. The MPO released draft Socioeconomic Data at the March TAC meeting for input from the public, staff and local governments. Based on this feedback, changes have been made to the draft SE Data for its use in generating the Deficiency Analysis. The updated SE Data generally allocated a more realistic proportion of households and jobs to the suburban and urban areas (the draft SE Data had allocated too much growth in the city and town centers). The updated SE Data is depicted in the tables and maps below. The first document is a table that presents the household and employment growth by jurisdiction. The first set of maps shows the location of household and job growth between 2010 and 2040 in a detailed grid pattern. The remaining sets of maps use so called dot maps to show the relative location of 2010, Growth and 2040 households and jobs.

2010 SE Data Estimate

Note: each dot equals ten households or ten jobs.

2040 SE Data Forecast

Note: each dot equals ten households or ten jobs.

Growth (from 2010 to 2040)

Note: each dot equals ten households or ten jobs.

Growth (from 2010 to 2040) Shown by Grid

Travel Time

The table below shows the travel time between key destinations in the Triangle region in 2010 and 2040, and calculates the change in that travel time. These travel times are for the afternoon peak period, which is 3:30pm to 7:30pm. The map shows the average travel time for the morning and afternoon peak period, the connector lines becoming a "hotter" color as the percentage increase in travel time from 2010 to 2040 becomes greater (i.e., congestion increases).