TEMPORARY LOSSES OF HIGHWAY CAPACITY AND IMPACTS ON PERFORMANCE: PHASE 2

8. Railroad Crossings

8.1 Methodology

Railroad-highway at-grade crossings cause delays when vehicles must stop to yield the right of way to trains. This temporarily reduces the highway capacity to zero for a brief period of time, depending on the speed and the length of the train. Estimates of delays at railroad-highway crossings for TLC2 were based on data produced by a study conducted by the Federal Railroad Administration (FRA) Office of Policy and Program Development (unpublished data). The FRA delay estimates were based on data compiled in the FRA Highway-Rail Crossing Database (U.S. DOT/FRA 2003) and methodologies used in the Highway-Rail Grade Crossing Evaluation Software, or GradeDec 2000 (U.S. DOT/FRA 2002).

In general, the delay estimates are based on queuing theory. Highway vehicle delay depends on the highway vehicle arrival rate (highway traffic volume), frequency of the crossing blockage (railroad traffic volume), and the blockage time (train speed and length). The estimates produced by FRA are for all highway-rail at-grade crossings. Since delays on minor arterials, collectors, and local roads are beyond the scope of TLC2, only those delays incurred on principal arterials were tabulated—Interstates do not have at-grade crossings.

8.2 Results

This study estimates that at-grade highway-railroad crossings caused about 2.9 million vehicle-hours of delay on principal arterials in 1999. Most of this delay (91 percent) occurred in urban areas, and most of the urban delay occurred during off-peak hours. Crossings in small urban areas accounted for nearly half (48 percent) of the delay, followed by those in very large urban areas (23 percent). Delay at crossings in medium and large urban areas, combined, only accounted for about 20 percent. Crossings in rural areas accounted for 9 percent of delay. Overall, 96 percent of all delay occurred during off-peak or non-congested peak hours; only 4 percent occurred during congested, peak-hour traffic conditions.

Figure 26. Nearly half of the delay from highway-rail at-grade crossings was experienced in small urban areas.

Table 30. Delay from at-grade highway-railroad crossings, 1999
Highway type	Urban area size*	Peak period^†	Congestion level^‡	Delay (1,000 veh-hrs)
Urban other principal arterials	Very large	Peak	Congested	41.0
		Peak	Not congested	173.7
		Off-peak		457.4
	Large	Peak	Congested	20.8
		Peak	Not congested	107.6
		Off-peak		273.7
	Medium	Peak	Congested	7.9
		Peak	Not congested	47.0
		Off-peak		116.9
	Small	Peak	Congested	46.4
		Peak	Not congested	414.1
		Off-peak		981.1
	Total			2,687.6
Rural other principal arterials		Peak	Congested	3.4
		Peak	Not congested	71.8
		Off-peak		184.4
		Total		259.6
Total				2,947.2
Footnotes: * Urban area size categories are based on population: very large – more than 3 million; large – 1 to 3 million; medium 0.5 to 1 million; small – less than 0.5 million. ^† Peak periods: 6:00 am to 9:30 am and 3:30 pm to 7:00 pm Monday through Friday; all others considered non-peak. ^‡ A roadway section is considered congested during the peak periods if its Volume/Service Flow Ratio (V/SF) is greater than 95%.

8.3 Reliability

The estimates of delay due to at-grade highway-railroad crossings are taken directly from a database prepared by a Federal Railroad Administration study. The results of the study have been published in the 2002 Status of the Nation's Highways, Bridges, and Transit: Conditions & Performance, Report to Congress, but the baseline delay estimates used by TLC are not published in the Conditions and Performance Report. Potential improvements in delay under different investment scenarios are presented in that report. The baseline delay information used for TLC2 is qualified as having a medium degree of confidence.

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