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5.0 Highway Truck Bottlenecks

5.1 Overview

We located and estimated truck hours of delay for 14 types of highway truck bottlenecks. Table 5.1 lists the types of bottlenecks and the annual truck hours of delay associated with each type. The bottleneck types are sorted in descending order of truck hours of delay by constraint type (e.g., interchange, geometry, intersection, and capacity) and then within each group by the truck hours of delay for each bottleneck type.

Table 5.1 Truck Hours of Delay by Type of Highway Freight Bottleneck
Bottleneck Type National Annual Truck Hours
of Delay, 2004 (Estimated)
Constraint Roadway Freight Route
Interchange Freeway Urban Freight Corridor 123,895,000
      Subtotal 123,895,000*
Steep Grade Arterial Intercity Freight Corridor 40,647,000
Steep Grade Freeway Intercity Freight Corridor 23,260,000
Steep Grade Arterial Urban Freight Corridor 1,509,000
Steep Grade Arterial Truck Access Route 303,000
      Subtotal 65,718,000
Signalized Intersection Arterial Urban Freight Corridor 24,977,000
Signalized Intersection Arterial Intercity Freight Corridor 11,148,000
Signalized Intersection Arterial Truck Access Route 6,521,000
Signalized Intersection Arterial Intermodal Connector 468,000
      Subtotal 43,113,000
Lane Drop Freeway Intercity Freight Corridor 5,221,000
Lane Drop Arterial Intercity Freight Corridor 3,694,000
Lane Drop Arterial Urban Freight Corridor 1,665,000
Lane Drop Arterial Truck Access Route 41,000
Lane Drop Arterial Intermodal Connector 3,000
      Subtotal 10,622,000
      Total 243,032,000
* The delay estimation methodology calculated delay resulting from queuing on the critically congested roadway of the interchange (as identified by the scan) and the immediately adjacent highway sections. Estimates of truck hours of delay are based on two-way traffic volumes. However, the methodology did not calculate delay on the other roadway at the interchange. This means that truck hours of delay were calculated on only one of the two intersecting highways or two of the four legs on an interchange, probably underreporting total delay at the interchange. The bottleneck delay estimation methodology also did not account for the effects of weaving and merging at interchanges, which aggravates delay, but could not be calculated from the available HPMS data. Estimates have been rounded to the nearest thousand.
The HPMS sampling framework supports expansion of volume-based data from these sample sections to a national estimate, but does not support direct estimation of the number of bottlenecks. Estimates of truck hours of delay are based on two-way traffic volumes. Estimates have been rounded to the nearest thousand.
Source: Cambridge Systematics.

The bottlenecks accrue 243 million hours of delay annually. At a delay cost of $32.15 per hour, the conservative value used by the FHWA's Highway Economic Requirements System model for estimating national highway costs and benefits, the direct user cost of the bottlenecks is about $7.8 billion per year.1

The individual bottlenecks in each category are unique and assigned to only one bottleneck type or category. Bottlenecks are not double counted across categories.

5.2 Interchange Bottlenecks for Trucks

We located 227 interchange bottlenecks on freeways serving as urban freeway corridors. Most of these bottlenecks were at urban Interstate interchanges. The interchange bottlenecks include freeway-to-freeway interchanges and freeway-to-arterial interchanges. The bottlenecks were located by scanning the HPMS Universe database and represent a reasonably complete national inventory of this type of bottleneck. The total delay associated nationally with these bottlenecks in 2004 was estimated at about 124 million truck hours or 51 percent of the estimated total. At a delay cost of $32.15 per hour, the direct user cost of the bottlenecks is about $4 billion per year. The truck hours of delay were estimated using truck volumes and highway capacity calculations drawn from the FHWA's Freight Analysis Framework (FAF) database by Battelle.

Figure 5.1 shows the location of all highway interchange bottlenecks for trucks. The bottleneck locations are indicated by a solid dot. Most are located on urban Interstate interchanges. The size of the open circles accompanying each dot indicates the relative annual truck hours of delay associated with the bottleneck.

Figure 5.1 Interchange Capacity Bottlenecks on Freeways Used as Urban Truck Corridors

Map of the continental United States showing the interstate highway system as a network. Highway interchange bottlenecks are indicated by a solid dot, with open circles sized to indicate the truck hours of delay on an annual basis. Population centers along the East coast, in the Midwest, and on the West coast states account for the majority of bottlenecks for trucks.
Source: Cambridge Systematics, Inc.

Figure 5.2 is a histogram showing the distribution of truck hours of delay for all highway interchange bottlenecks for trucks. The individual bottlenecks, each represented on the horizontal axis by an identification number, are sorted in descending order of annual truck hours of delay, which are measured on the vertical axis. Of the 227 highway interchange bottlenecks, 173 cause more than 250,000 truck hours of delay annually (equivalent to a direct user cost of about $8 million per year). By comparison only a few dozen of all the other truck bottlenecks cause more than 250,000 truck hours of delay annually.

Figure 5.2 Distribution of Annual Truck Hours of Delay at Highway Interchange Bottlenecks, 2004

Histogram showing distribution of truck hours of delay for 227 interchange bottlenecks, sorted in descending order of annual truck hours of delay. The top five bottlenecks each account for more than 1.4 million truck hours of delay. The next 20 account for more than 0.8 million truck hours of delay. The trend for the remaining bottlenecks is a long curve approaching zero.
Source: Cambridge Systematics, based on FHWA Freight Analysis Framework data.

The delay estimation methodology calculated truck delay resulting from queuing on the critically congested roadway of the interchange (as identified by the scan) and the immediately adjacent highway sections. It did not calculate delay on the other roadway at the interchange. This means that truck hours of delay were calculated on only one of the two intersecting highways or two of the four legs on a interchange, potentially underreporting total delay at the interchange. The bottleneck delay estimation methodology also did not account for the effects of weaving and merging at interchanges, which aggravates delay, but could not be calculated from the available HPMS data.

The next two tables list the top highway interchange bottlenecks for trucks. Table 5.2 lists the top 25 interchange bottlenecks ranked by annual hours of delay for all trucks. Table 5.3 lists the top 25 interchange bottlenecks ranked by annual hours of delay for large trucks making trip greater than 500 miles.

There is overlap between the tables, but the ranking by all trucks tends to flag interchanges in the nation's major freight hubs and trade gateways that serve high volumes of metropolitan and intercity truck traffic. The ranking by large trucks making trips greater than 500 miles tends to flag interchange bottlenecks that sit astride many of the key intersections of the nation's long-haul and transcontinental freight corridors.

In the tables, AADT is the abbreviation for Annual Average Daily Traffic, the number of vehicles, including automobiles and trucks of all sizes, traveling the critically congested roadway each day. AADTT is the abbreviation for Annual Average Daily Truck Traffic, the number of trucks of all sizes traveling the critically congested roadway each day. For comparison, Table 5.4 lists the top 25 most congested highway interchanges as identified in the American Highway Users Alliance study. These bottlenecks are ranked in descending order of annual hours of delay for all vehicles, including trucks.

Appendix A provides the full set of tables—as listed in Table 5.5—along with detailed definitions of each of the column headings and information about the sources of the data reported in the tables.

Table 5.2 Top 25 Highway Interchange Bottlenecks for Trucks
Ranked By Annual Hours of Delay for All Trucks*
Bottleneck All Vehicles-2004 All Trucks-2004 "Large Trucks Making Longer Distance Trips"-2004
Location Urban Area Critically Congested Route No. No. of Lanes AADT Daily Minutes of Delay per Vehicle AADTT Percent of All Vehicles Annual Hours of Delay All Trucks All Trips Trips Greater Than 500 Miles
AADTT Percent of All Trucks Annual Hours of Delay Annual Commodity Tons Annual Commodity Value Percent of Large Truck Trips Annual Hours of Delay
I-90 @ I-290 Buffalo-Niagara Falls 90 4 136,500 8.3 33,100 24% 1,661,900 7,300 22% 367,000 2,632,500 $2,968,000 58% 212,900
I-285 @ I-85 Interchange ("Spaghetti Junction") Atlanta 285 8 265,300 10.0 27,100 10% 1,641,200 7,800 29% 472,600 2,943,700 $3,262,000 52% 245,800
I-17 (Black Canyon Fwy): I-10 Interchange (the "Stack") to Cactus Phoenix 17 6 217,300 9.2 28,900 13% 1,608,500 9,000 31% 501,600 3,326,700 $3,792,000 48% 240,800
I-90/94 @ I-290 Interchange ("Circle Interchange") Chicago-Northwestern IN 90 8 305,800 9.7 26,300 9% 1,544,900 9,200 35% 540,400 3,718,000 $4,218,000 53% 286,400
San Bernardino Fwy Los Angeles 10 8 268,700 7.2 34,900 13% 1,522,800 11,200 32% 488,700 4,094,500 $4,780,000 31% 151,500
I-94 (Dan Ryan Expwy) @ I-90 Skyway Split (Southside) Chicago-Northwestern IN 94 8 271,700 7.9 31,600 12% 1,512,900 11,100 35% 531,500 4,485,900 $5,089,000 53% 281,700
I-285 @ I-75 Interchange Atlanta 285 6 226,300 9.6 25,700 11% 1,497,300 7,400 29% 431,500 2,792,800 $3,095,000 52% 224,400
SR 134 @ SR 2 Interchange Los Angeles 134 8 247,900 8.3 29,600 12% 1,489,400 9,500 32% 477,500 3,473,000 $4,054,000 31% 148,000
I-77 @ Tryon Rd Charlotte 77 6 170,500 8.3 29,600 17% 1,487,100 7,300 25% 367,000 2,700,200 $2,983,000 45% 165,200
Long Beach Fwy Los Angeles 710 8 246,100 8.3 27,500 11% 1,380,300 8,800 32% 442,400 3,217,100 $3,756,000 31% 137,100
I-20 @ I-285 Interchange Atlanta 20 6 187,200 8.3 27,000 14% 1,359,400 7,800 29% 392,100 2,943,700 $3,262,000 52% 203,900
I-80/I-94 split (Southside) Chicago-Northwestern IN 80 4 139,600 8.6 25,600 18% 1,343,600 9,000 35% 472,400 3,637,200 $4,127,000 53% 250,400
SR 60 @ I-605 Interchange Los Angeles 60 8 233,000 8.3 26,100 11% 1,314,200 8,400 32% 422,300 3,070,900 $3,585,000 31% 130,900
Pulaski Rd @ I-55 Chicago-Northwestern IN 55 6 197,200 7.5 28,700 15% 1,300,400 10,000 35% 453,700 4,041,300 $4,585,000 53% 240,500
I-75 @ I-85 Interchange Atlanta 75 10 339,600 9.1 23,400 7% 1,288,800 6,800 29% 374,900 2,566,300 $2,844,000 52% 194,900
I-93 @ I-95 Interchange Boston 93 6 188,400 8.3 25,500 14% 1,280,100 2,800 11% 140,800 1,020,000 $1,220,000 36% 50,700
I-290 @ I-355 Chicago-Northwestern IN 290 6 223,100 8.3 24,800 11% 1,246,200 8,700 35% 437,300 3,515,900 $3,989,000 53% 231,800
I-405 (San Diego Fwy) @ I-605 Interchange Los Angeles 405 10 331,700 9.8 20,900 6% 1,245,500 6,700 32% 398,600 2,449,400 $2,859,000 31% 123,600
I-80 @ Central St. San Francisco-Oakland 80 8 270,200 8.3 23,800 9% 1,196,700 7,800 33% 392,100 2,851,500 $3,329,000 29% 113,700
San Gabriel River Fwy Los Angeles 91 10 295,700 8.1 24,100 8% 1,194,300 7,700 32% 381,100 2,815,000 $3,286,000 31% 118,100
I-20 @ Fulton St. Atlanta 20 6 207,300 8.1 23,700 11% 1,172,700 6,800 29% 336,500 2,566,300 $2,844,000 52% 175,000
*Annual Hours of Delay for All Trucks is the number of hours of delay accruing annually to all trucks delayed by congestion at the bottleneck. (e.g., Daily Minutes of Delay per Vehicle multiplied by 2004 AADTT for All Trucks). Because the underlying Highway Performance Monitoring System data do not detail traffic counts by time of day, the actual number of trucks exposed to peak-period congestion is unknown, and therefore the reported truck hours of delay shown here provide good index to the relative impacts of the bottlenecks, but are not reliable absolute numbers.
Table 5.3 Top 25 Highway Interchange Bottlenecks for Trucks
Ranked By Annual Hours of Delay for Large Trucks Making Trips Longer Than 500 Miles*
Bottleneck All Vehicles-2004 All Trucks-2004 "Large Trucks Making Longer Distance Trips"-2004
Location Urban Area Critically Congested Route No. No. of Lanes AADT Daily Minutes of Delay per Vehicle AADTT Percent of All Vehicles Annual Hours of Delay All Trucks All Trips Trips Greater Than 500 Miles
AADTT Percent of All Trucks Annual Hours of Delay Annual Commodity Tons Annual Commodity Value Percent of Large Truck Trips Annual Hours of Delay
I-24 @ I-440N Interchange Chattanooga (TN-GA) 24 4 118,200 8.3 18,500 16% 927,500 9,200 50% 462,500 3,330,000 $3,750,000 85% 393,100
U.S. 95 @ I-15 Interchange ("Spaghetti Bowl") Las Vegas 95 6 199,900 9.8 11,300 6% 670,400 5,600 50% 333,100 1,992,500 $2,286,000 90% 299,800
I-90/94 @ I-290 Interchange ("Circle Interchange") Chicago-Northwestern IN 90 8 305,800 9.7 26,300 9% 1,544,900 9,200 35% 540,400 3,718,000 $4,218,000 53% 286,400
I-94 (Dan Ryan Expwy) @ I-90 Skyway Split (Southside) Chicago-Northwestern IN 94 8 271,700 7.9 31,600 12% 1,512,900 11,100 35% 531,500 4,485,900 $5,089,000 53% 281,700
I-75 @ I-74 Interchange Cincinnati (OH-KY) 75 6 193,100 9.7 19,200 10% 1,128,900 6,900 36% 405,300 2,735,200 $3,044,000 63% 255,300
I-10 @ I-110 Interchange Baton Rouge 10 6 150,400 7.2 15,200 10% 665,000 8,600 57% 375,200 3,163,900 $3,591,000 68% 255,100
I-80/I-94 split (Southside) Chicago-Northwestern IN 80 4 139,600 8.6 25,600 18% 1,343,600 9,000 35% 472,400 3,637,200 $4,127,000 53% 250,400
I-285 @ I-85 Interchange ("Spaghetti Junction") Atlanta 285 8 265,300 10.0 27,100 10% 1,641,200 7,800 29% 472,600 2,943,700 $3,262,000 52% 245,800
I-17 (Black Canyon Fwy): I-10 Interchange (the "Stack") to Cactus Phoenix 17 6 217,300 9.2 28,900 13% 1,608,500 9,000 31% 501,600 3,326,700 $3,792,000 48% 240,800
Pulaski Rd @ I-55 Chicago-Northwestern IN 55 6 197,200 7.5 28,700 15% 1,300,400 10,000 35% 453,700 4,041,300 $4,585,000 53% 240,500
I-290 @ I-355 Chicago-Northwestern IN 290 6 223,100 8.3 24,800 11% 1,246,200 8,700 35% 437,300 3,515,900 $3,989,000 53% 231,800
I-40 @ I-24 Interchange Nashville 40 4 147,600 8.3 14,600 10% 735,200 5,800 40% 291,600 2,099,300 $2,364,000 77% 224,500
I-285 @ I-75 Interchange Atlanta 285 6 226,300 9.6 25,700 11% 1,497,300 7,400 29% 431,500 2,792,800 $3,095,000 52% 224,400
I-35 @ Martin Luther King Jr Austin 35 6 229,500 8.3 12,600 5% 635,000 11,200 89% 563,000 4,123,900 $4,768,000 39% 219,600
I-15 between Tropicana and Flamingo Las Vegas 15 6 165,900 6.4 12,400 7% 486,700 6,200 50% 242,800 2,206,000 $2,530,000 90% 218,500
I-12 @ Amite River, Baton Rouge Baton Rouge 12 4 105,000 6.4 14,400 14% 561,900 8,100 57% 317,200 2,980,000 $3,383,000 68% 215,700
I-75 @ U.S. 35 Interchange Dayton 75 4 127,400 8.3 18,400 14% 923,100 7,900 43% 397,100 3,131,600 $3,485,000 54% 214,400
I-90 @ I-290 Buffalo-Niagara Falls 90 4 136,500 8.3 33,100 24% 1,661,900 7,300 22% 367,000 2,632,500 $2,968,000 58% 212,900
I-20 @ I-285 InterchangeAtlanta 20 6 187,200 8.3 27,000 14% 1,359,400 7,800 29% 392,100 2,943,700 $3,262,000 52% 203,900
I-75 @ I-85 Interchange Atlanta 75 10 339,600 9.1 23,400 7% 1,288,800 6,800 29% 374,900 2,566,300 $2,844,000 52% 194,900
I-264 @ I-64 Interchange Louisville (KY-IN) 264 6 181,100 8.3 16,400 9% 825,500 5,400 33% 271,400 1,990,200 $2,218,000 69% 187,300
I-55 (Stevenson Expwy) @ I-294 Interchange Chicago-Northwestern IN 55 6 172,600 9.6 17,200 10% 1,001,600 6,000 35% 349,900 2,424,800 $2,751,000 53% 185,400
I-80 @ I-480 Interchange Omaha (NE-IA) 80 5 173,600 7.9 13,800 8% 658,500 4,500 32% 215,500 1,638,000 $1,856,000 86% 185,300
I-76 @ SR 77 Interchange+J179 Akron 76 4 122,600 8.3 14,000 11% 705,200 7,000 50% 351,900 2,774,800 $3,088,000 52% 183,000
I-15 @ I-215 Interchange (the "Fishbowl") Las Vegas 15 6 165,600 6.6 10,100 6% 403,200 5,000 50% 200,300 1,779,100 $2,041,000 90% 180,300
*Annual Hours of Delay for All Trucks is the number of hours of delay accruing annually to all trucks delayed by congestion at the bottleneck. (e.g., Daily Minutes of Delay per Vehicle multiplied by 2004 AADTT for All Trucks). Because the underlying Highway Performance Monitoring System data do not detail traffic counts by time of day, the actual number of trucks exposed to peak-period congestion is unknown, and therefore the reported truck hours of delay shown here provide good index to the relative impacts of the bottlenecks, but are not reliable absolute numbers.
Table 5.4 The Worst Physical Bottlenecks in the United States, 2002
American Highway Users Alliance Study
Rank City Freeway Location Annual Hours
of Delay
(Hours in Thousands)
1Los AngelesU.S. 101U.S. 101 (Ventura Freeway) at I-405 Interchange 27,144
2HoustonI-610I-610 at I-10 Interchange (West)25,181
3ChicagoI-90I-90/94 at I-290 Interchange ("Circle Interchange")25,068
4PhoenixI-10I-10 at SR 51/SR 202 Interchange ("Mini-Stack")22,805
5Los Angeles I-405I-405 (San Diego Freeway) at I-10 Interchange22,792
6Atlanta I-75I-75 south of the I-85 Interchange 21,045
7Washington (DC-Maryland-Virginia)I-495I-495 at I-270 Interchange 19,429
8Los Angeles I-10I-10 (Santa Monica Freeway) at I-5 Interchange18,606
9Los Angeles I-405I-405 (San Diego Freeway) at I-605 Interchange18,606
10Atlanta I-285I-285 at I-85 Interchange ("Spaghetti Junction") 17,072
11ChicagoI-94I-94 (Dan Ryan Expressway) at I-90 Skyway Split (Southside) 16,713
12PhoenixI-17I-17 (Black Canyon Freeway) at I-10 Interchange (the "Stack") to Cactus Road16,310
13Los AngelesI-5I-5 (Santa Ana Freeway) at SR 22/SR 57 Interchange ("Orange Crush")16,304
14ProvidenceI-95I-95 at I-195 Interchange15,340
15Washington (DC-Maryland-Virginia)I-495I-495 at I-95 Interchange15,035
16TampaI-275I-275 at I-4 Interchange ("Malfunction Junction")14,371
17AtlantaI-285I-285 at I-75 Interchange 14,333
18SeattleI-5I-5 at I-90 Interchange14,306
19ChicagoI-290I-290 (Eisenhower Expressway) Between Exits 17b and 23a 14,009
20HoustonI-45I-45 (Gulf Freeway) at U.S. 59 Interchange13,944
21San JoseU.S. 101U.S. 101 at I-880 Interchange12,249
22Las VegasU.S. 95U.S. 95 west of the I-15 Interchange ("Spaghetti Bowl")11,152
23San DiegoI-805I-805 at I-15 Interchange10,992
24CincinnatiI-75I-75, from Ohio River Bridge to I-71 Interchange10,088
Source: Unclogging America's Arteries: Effective Relief for Highway Bottlenecks, American Highway Users Alliance, February 2004. Delay is the extra time it would take to travel through the bottlenecks compared to completely uncongested conditions. The report did not consider many severe bottlenecks from the New York City area. As most travelers know, congestion in and around the boroughs of New York can be significant. However, a very large amount of delay in the New York area is related to bridge and tunnel crossings into Manhattan, most of which are toll facilities. Also, while the New York metropolitan area is laced with Interstates, parkways, and expressways, they seldom reach the proportions seen in other major areas, except where multiple highways converge on bridge of tunnel crossings. (A typical lane configuration for a New York area freeway is six lanes, three in each direction. But there are many of these.) Toll facilities were excluded from the study because toll facilities are fundamentally different from other physical bottlenecks (such as freeway-to-freeway interchanges) that are prevalent around the country. Delay comparisons between toll facilities and other types of bottlenecks might not be consistent since different modeling techniques would be used. If objective field measurements of delay could be made at all locations around the country, several river crossings into Manhattan would no doubt be included in a list of the nation's worst bottlenecks.

Table 5.5 List of Appendix A Tables of Highway Interchange Bottlenecks for Trucks
Appendix A Table Number Bottlenecks Ranked in Descending Order of Annual
Truck Hours of Delay for …
Table A.1Top 25All Trucks
Table A.2Top 25Large Trucks Making Longer Distance Trips ("FAF Trucks")
Table A.3Top 25Large Trucks Making Longer Distance Trips ("FAF Trucks") Greater Than 500 Miles
Table A.4All top-ranked bottlenecks as identified in Tables 6.1, 6.2, and 6.3, eliminating duplicate listingsLarge Trucks Making Longer Distance Trips ("FAF Trucks") Greater Than 500 Miles
Table A.5AllAll Trucks

5.3 Steep-Grade Bottlenecks for Trucks

We located 859 bottlenecks created by steep grades on freeways and arterials. These bottlenecks were located by scanning the HPMS Sample database for roadway sections with grades greater than 4.5 percent and more than a mile long. These bottlenecks represent a partial inventory of this type of bottleneck. Using HPMS expansion factors, we estimate that the total delay associated nationally with this type of bottleneck in 2004 was about 66 million truck hours or 27 percent of the total truck hours of delay. At a delay cost of $32.15 per hour, the direct user cost of the bottlenecks is about $2.1 billion per year.

The estimates were made by applying the sample expansion factors provided in the HPMS Sample database to truck hours of delay for each the identified bottlenecks. The statistical framework for the HPMS makes it possible to estimate the total truck hours of delay associated nationally with freight bottlenecks on these roadway but not to estimate the actual number of bottlenecks or pinpoint all their locations.2 The truck volumes and highway capacity calculations were based on the HPMS Sample statistics.

Steep-grade bottlenecks on arterial roadways serving as intercity freight corridors accounted for 40 million of the 66 million truck hours of delay attributed to steep-grade bottlenecks. Figure 5.3 shows the location of the steep-grade bottlenecks on arterial roadways serving as intercity freight corridors. The bottleneck locations are indicated by a solid dot. Most are located on urban Interstate interchanges. The size of the open circles accompanying each dot indicates the relative annual truck hours of delay associated with the bottleneck. Again, because of the constraints of the HPMS Sample database, the map does not identify all bottlenecks of this type.

Figure 5.3 Steep Grade Bottlenecks on Arterials Used As Intercity Truck Corridors
HPMS Sample Sections Only

Map of the continental United States showing locations of steep grade bottlenecks on arterial roadways serving as intercity freight corridors. Dense clusters are shown in Vermont and New Hampshire; in West Virginia, Kentucky, Virginia, North Carolina, and South Carolina; in Georgia; in Tennessee and Indiana; in Michigan; in California; and in Washington, Idaho, Montana, Wyoming, Utah, and Colorado.

Figure 5.4 shows the distribution of truck hours of delay by bottleneck for all steep-grade bottlenecks. The vertical-axis scale has been adjusted downward to the highest delay value in the chart. The figure shows only those bottlenecks identified from the HPMS Sample database and therefore undercounts the actual number of these bottlenecks. The delay hours shown are the unexpanded estimates for the individual bottlenecks.

Figure 5.4 Distribution of Annual Truck Hours of Delay at Steep Grade Bottlenecks
2004, HPMS Sample Sections Only

Line chart showing annual truck hours of delay over more than 800 steep grade bottlenecks. The curve starts about 0.5 million and swings down to less than 0.1 by bottleneck 75, and rapidly approaches 0 by bottleneck 400.
Source: Cambridge Systematics, based on FHWA HPMS 2002 data.

5.4 Signalized Intersection Bottlenecks for Trucks

We located 517 bottlenecks caused by signalized intersections on arterials. These bottlenecks were located by scanning the HPMS Sample database for signalized roadway sections with a volume-to-capacity ratio greater than 0.925. These bottlenecks also represent a partial inventory of this type of bottleneck. Expanding the sample, we estimate that the total delay associated nationally with this type of bottleneck in 2004 was about 43 million truck hours of delay. At a delay cost of $32.15 per hour, the direct user cost of the bottlenecks is about $1.4 billion per year. The truck volumes and highway capacity calculations were based on the HPMS Sample statistics.

Signalized-intersection bottlenecks on arterials serving as urban freight corridors accounted for 25 million truck hours of delay or 58 percent of the total for Signalized-intersection bottlenecks. Figure 5.5 shows the location of signalized-intersection bottlenecks on arterials serving as urban freight corridors. The bottleneck locations are indicated by a solid dot. Most are located on urban Interstate interchanges. The size of the open circles accompanying each dot indicates the relative annual truck hours of delay associated with the bottleneck.

Figure 5.5 Signalized Intersection Bottlenecks on Arterials Used As Urban Truck Corridors
HPMS Sample Sections Only

Map of the continental United States showing locations of signalized bottlenecks on arterials used as urban corridors. Dense clusters are shown in western Pennsylvania, New Jersey, Connecticut, and Rhode Island; in Washington, D.C.; in North and South Carolina; in Louisiana; in Wisconsin, northern Illinois, and northern Indiana; and in Washington state.

Figure 5.6 shows the distribution of truck hours of delay by bottleneck for all signalized-intersection bottlenecks for trucks. Again, the vertical-axis scale has been adjusted downward to the highest delay value in the chart. The figure shows only those bottlenecks identified from the HPMS Sample database and therefore undercounts the actual number of these bottlenecks. The delay hours shown are the unexpanded estimates for the individual bottlenecks.

Figure 5.6 Distribution of Truck Hours of Delay at Signalized Intersection Bottlenecks
2004, HPMS Sample Sections Only

Line chart showing annual truck hours of delay over more than 500 signalized intersection bottlenecks. The curve starts about 325 thousand and swings sharply down to less than 50 thousand by bottleneck 50 and gradually approaches 0 by bottleneck 500.
Source: Cambridge Systematics, based on FHWA HPMS 2002 data.

5.5 Lane-Drop Bottlenecks for Trucks

Finally, we located 507 bottlenecks created by lane drops and restricted capacity on arterials and freeways, typically locations where a roadway necks down from three lanes to two or two lanes to one and the volume-to-capacity ratio is greater than 0.925. These bottlenecks were located by scanning the HPMS Sample database. Expanding the sample, we estimated that the total delay from this type of bottleneck nationally in 2004 was about 11 million truck hours of delay or 5 percent of the total. At a delay cost of $32.15 per hour, the direct user cost of the bottlenecks is about $354 million per year. The truck volumes and highway capacity calculations were based on the HPMS Sample statistics.

Lane-drop bottlenecks on freeways serving intercity freight corridors accounted for 5.6 million annual truck hours of delay or about 53 percent, Figure 5.8 shows the location of lane-drop bottlenecks on freeways serving intercity freight corridors. The bottleneck locations are indicated by a solid dot. Most are located on urban Interstate interchanges. The size of the open circles accompanying each dot indicates the relative annual truck hours of delay associated with the bottleneck.

Figure 5.7 Capacity Bottlenecks on Freeways Used As Intercity Truck Corridors
HPMS Sample Sections Only

Map of the continental United States showing the interstate highway system as a network. Freeway bottlenecks are indicated by a solid dot, with open circles sized to indicate the truck hours of delay on an annual basis. Corridors along the East coast, in the Carolinas, in the Midwest, and in the West coast states account for the majority of bottlenecks for trucks.

Figure 5.9 shows the distribution of truck hours of delay by bottleneck for all lane-drop bottlenecks for trucks. The vertical-axis scale has been adjusted downward to the highest delay value in the chart. The figure shows only those bottlenecks identified from the HPMS Sample database and therefore undercounts the actual number of these bottlenecks. The delay hours shown are the unexpanded estimates for the individual bottlenecks.

Figure 5.8 Distribution of Annual Truck Hours of Delay at Lane-Drop Bottlenecks
2004, HPMS Sample Sections Only

Line chart showing distribution of annual truck hours of delay at 245 lane drop bottlenecks. The curve starts at above 600 thousand hours and drops steeply to less than 100 thousand by bottleneck 10, swings to about 20 thousand by bottleneck 50, and rapidly approaches zero by bottleneck 200.
Source: Cambridge Systematics, based on FHWA HPMS 2002 data.

1 The FHWA Highway Economic Requirements System model uses a current value of truck time of $32.15 per hour. Other researchers have suggested higher rates, typically between $60 and $70 per hour.
2 Our best professional guess is that the total number of steep-grade, signalized-intersection, and lane-drop bottlenecks reported in this paper represent 30 to 50 percent of the actual total of these types of truck bottlenecks. However, this guesstimate is based solely on our experience working with State and Federal roadway inventory data bases such as the Federal Highway Performance Monitoring System. We would not be surprised to find that the actual total was higher.

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