Friday, April 06, 2007

More on the River Road Barrier

Courtesy of the Tenleytown Listserv and Karyn LeBlanc of DDOT:

Greetings everyone,

I wanted to address the additional questions that were posted to DDOT after my report on March 16, 2007. I hope this suffices to answer some questions that have been pending. If not, or if you have any further questions, as always, please feel free to let me know.

DDOT technical teams are continuing their design and pre-construction meetings and are still scheduled to begin work on the intersection in late April 2007. I expect to have a start date within the next week or so and will forward the information to the community as soon as it is available.

Best to all,

1. How much money will this project cost taxpayers?

The traffic signal and intersection improvements will cost an estimated $490K. The estimate includes the installation of the traffic signal as well infrastructure improvements, channelized median installation, sidewalk and curb upgrades, pedestrian improvements to include pedestrian countdown signals and crosswalks, streetlight and manhole installation. This estimate is based on using a wireless detection device in place of the previously recommended in-ground device. This represented a cost savings of $65K.

2. What definition does DDOT use for "Collector Streets?"

It is best to answer this question in two parts. The following information is located in "The Functional Classification of Streets in the District of Columbia," developed to be consistent with Federal Highway Administration requirements under Title 23, Chapter 1, Part 470.

How does DDOT classify the streets in the District of Columbia?

Purpose of Functional Classification

The roadway network in the District of Columbia is arrayed into a system of categories that represent the use and function of each street. This system is called the Functional Classification of Streets. The functional categories range from Principal Arterials which are major traffic carriers in the city, to Local Streets, which serve redominantly local traffic and carry little to no through traffic. The street network is classified for a number of reasons. The primary reason being to assure that street improvement funds are allocated in a manner that insures that those streets that are the most important in maintaining the daily flow of people and goods throughout the city are given priority for construction funding. The classifications also play an important role in traffic planning. A goal of traffic planning is to funnel as much traffic as possible onto the major arteries in the city and discourage traffic from using the narrow neighborhood streets that comprise the major portion of the city network. The classification system details the extent to which streets are functioning as traffic carriers and is therefore use das a framework for planning such improvements as traffic signalization, channelizations, and various sign and pavement marking details. Likewise, the classifications can be used in determining which streets are candidates for traffic restraints.

Description of Functional Categories

The street network is split into four categories and three sub-categories.
They are;
1. Principal Arterial System
a. Interstate Highways
b. Other Freeways and Expressways
c. Other Principal Arterials
2. Minor Arterials
3. Collectors
4. Locals

[I will forgo providing information on Principal Arterial Systems and focus on Numbers 2-4. (If anyone would like this information, please let me know)]

Minor Arterials - These streets provide the connections between the principal arterial network and may service major flows in an area with no clearly defined principal arterial street. The characteristics of streets in this classification are:

1. Interconnect with the augment the principal arterial network;
2. May function as a principal during the peak periods;
3. Serve greater land use access than principals but access is subordinate to traffic movement;
4. Average daily traffic is greater than 8,000 and less than 20,000 vehicles per day;
5. Minimum of sharp grades and steep curves;
6. Serve bus and truck movements; and
7. May have peak period parking restrictions.

A typical minor arterial is Piney Branch Road, N.W. which carries two lanes of traffic in the peak period and one lane at all other times. It carries 15,000 vehicles per day.

Collectors - These streets serve a variety of functions, including providing direct access to major traffic generators, i.e. a METRO station, or large complex of apartments. They may be a connection from a neighborhood to the arterial network or may provide a connection between arterial streets in an area where no clearly defined minor arterial is present to handle the

1. Serve a split function of land use access and traffic movement;
2. Collect and distribute traffic in residential and commercial areas;
3. Average daily traffic is greater than 2,000 and less than 8,000 vehicles per day;
4. May provide direct access to a major traffic generator;
5. Serve local bus and commercial traffic; and
6. No peak period parking restrictions.

A typical collector is Fort Lincoln Drive, N.E. which provides access into the Fort Lincoln New Town Development.

Local streets - These roadways provide direct access to abutting lane use with a minimum of through traffic. Traffic volumes are less than 2,000 vehicles per day and bus and truck use is only to provide local service or delivery. By definition local streets comprise all streets not on a higher category.

What are the procedures for assigning streets to a particular classification?

[Again, I will forgo the information on the the first two sub-categories of principal arterials (if anyone would like this information, please let me know)]

...The remaining classifications are comprised of city streets that are assigned to a category based on a combination of physical and operational characteristics. Each street is assigned after a review of the pertinent data for each section. The date includes street width, number of lanes, traffic volumes (both peak and off peak), bus routes, parking regulations,
land use, and the relationship of the street with the regional and city roadway network. The classifications are based on use, and therefore existing travel patterns play a major role in the determination of the classification assigned. The data assembled for each street is compared to the desired characteristics for each classification (listed in previous section) and assignments are made accordingly.

Use and extend of each system - A primary goal in traffic planning is to accommodate as much traffic as practical on a minimum mileage of streets. The D.C. street systems' operation in this regard is demonstrated in Table 1, which details the proportional use of the street network by each functional classification.

Table 1

Proportion of
Functional Classification Miles (% of Total)
Daily Traffic
Principal Arterial 128 (12) 51%
Minor Arterial 156 (14) 30%
Collectors 150 (14) 10%
Local Streets 668 (60) 9%

This demonstrates the effectiveness of the present system; as the Principal arterial network which comprises only 12 percent of the roadway mileage carries 51% of the traffic and the local street system which is the major portion of the D.C. network carries less than 10 percent of the traffic in the city.

Policy Regarding Changes to the Assigned Classification

The Functional Classification of a street is not regarded as a permanent assignment or a rigid plan that must be maintained. It is only to be used as a framework for traffic planning. A tenet of the Department's transportation planning process is that no significant change can be effected on the operation of a street without due consideration of it's effect on adjacent streets. For example, if a street is carrying a daily flow of 12,000 vehicles per day and is classified as a minor arterial and the Department is requested by a citizen's group to reduce the vehicular flow and the classification, the response would not be "the street is an arterial and we cannot restrict the flow." The operation of the street in question and others in the area can be reviewed to determine if the traffic can be diverted to other roadways. If it can be diverted, and the measures to restrict traffic area implemented, the classification will be lowered to the appropriate level. If, however, it is determined that no restriction can be implemented without overloading an adjacent arterial or diverting traffic to local streets, the operation and classification must be maintained. Likewise, if the traffic volume on a street is increased due to a major development or other change in the area the classification would be upgraded accordingly.

3. Had funding been secured for the traffic light when Jeff Jennings told us, months ago, that it had? (If DDOT obtained a financial commitment from the federal government for the funds when Jeff told us DDOT had secured funding, why has DDOT decided to give the money back? If DDOT had not secured a commitment, didn't Jeff pass along false information to the community and, if so, who was responsible? (Note that Noble indicated at a public meeting that the light would be federally funded.)

As the traffic light is being locally funded, I can only conclude by these statements that my colleagues, in good faith, may have assumed the light could be federally funded and indicated as such at community meetings. However, the light is not going to be federally funded, it will be locally funded. My apologies for any confusion.

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