Thursday, May 29, 2008

A Better Way to Measure Traffic, Part Two

In Part One, we discussed how GPS-based traffic measurement could work on a county-wide basis. The Planning Department has already done test drives on several corridors, plotting out distances, times and speeds in evening rush hour. When combined with critical lane volume (CLV) measurements, we can get a sense of which corridors are really the worst rush hour drives in Montgomery County.

In general, there are two types of problematic corridors. First, there are stretches of major roads characterized by high volumes and low speeds. Second, there are stretches characterized by modest volumes and low speeds. The modest-volume corridors are no less troubled than the high-volume corridors. In fact, some corridors may record lower volumes because chains of clogged intersections prevent large numbers of cars from getting through.

Using Planning’s preliminary data, we have identified four high-volume and four modest-volume corridors that all recorded low travel speeds. These are the true problem areas in Montgomery County, not the “most-congested intersection” list that is based on flawed, one-day CLV estimates.

Today, we report the worst high-volume corridors and tomorrow we report the worse modest-volume corridors. Unlike the Planning staff, we do not rank them; I am sure Wisconsin Avenue drivers are just as miserable as Georgia Avenue drivers like myself. For each corridor, we report the date, time and results for the test drives as well as any CLV measurements taken in its component intersections. We also report the policy area standard CLV. Any intersections with CLVs measured above their policy area standard are rated as “failing” by the Planning Department.

The Worst High Volume, Low Speed Corridors

The following four corridors are characterized by high auto volume (often exceeding allowable policy area standards) and low speeds. Lots of cars can and do get through these areas, but the experience is agonizing.

Connecticut Avenue, Bradley Lane to the Beltway

Test Run
6/4/07 at 6:20 PM, Northbound
2.01 Miles in 19.6 Minutes, 6.1 MPH

PM Critical Lane Volumes
Connecticut at Bradley: 1577 (Recorded on 3/17/04)
Connecticut at East-West Highway: 1829 (Recorded on 3/29/06), Exceeds Standard
Connecticut at Jones Bridge: 2017 (Recorded on 6/6/07), Exceeds Standard
Connecticut at Beltway: 1245 North, 1100 South (Recorded on 3/9-3/10/04)
Policy Area CLV Standard: 1600

Notes: This is the major commuter route between Chevy Chase, Kensington and Downtown D.C.

Georgia Avenue, Arcola Avenue to Randolph Road

Test Run
6/4/07 at 5:15 PM, Northbound
0.69 Miles in 8.03 Minutes, 5.2 MPH

PM Critical Lane Volumes
Georgia at Arcola: 1471 (Recorded on 2/23/06)
Georgia at Randolph: 1910 (Recorded on 2/23/06), Exceeds Standard
Policy Area CLV Standard: 1600

Notes: Georgia at Randolph had the second-highest AM CLV in the county. A grade-separated interchange at this intersection is the county’s top priority among state construction projects. The state announced it would fund the project in January 2008. The Glenmont Metro Station is just to the north.

Rockville Pike, Congressional Lane to Edmonston Drive

Test Run #1
6/7/07 at 5:42 PM, Northbound
0.69 Miles in 4.62 Minutes, 9.0 MPH

Test Run #2
6/7/07 at 6:02 PM, Northbound
0.46 Miles in 2.93 Minutes, 9.4 MPH

PM Critical Lane Volumes
Rockville Pike at Congressional: 1538 (Recorded on 6/3/04), Exceeds Standard
Rockville Pike at Edmonston: 1590 (Recorded on 10/13/04), Exceeds Standard
Policy Area CLV Standard: 1500

Notes: This corridor is just north of the Twinbrook Metro Station and is adjacent to the Woodmont Country Club.

Wisconsin Avenue, Battery Lane to Cedar Lane

Test Run
5/12/05 at 4:52 PM, Northbound
1.24 Miles in 11.0 Minutes, 6.8 MPH

PM Critical Lane Volumes
Wisconsin at Battery: 1745 (Recorded on 2/8/07)
Wisconsin at Jones Bridge: 1536 (Recorded on 12/22/05)
Wisconsin at Cedar: 1996 (Recorded on 9/7/06), Exceeds Standard
Policy Area CLV Standard: 1600 (1800 at Battery)

Notes: This corridor extends from the northern edge of Downtown Bethesda through the National Naval Medical Center and is just south of the Beltway interchange. The extremely-congested, high-volume traffic provides a strong justification for BRAC-related transportation work.

Tomorrow, we will look at corridors with modest Critical Lane Volumes and slow speeds.

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