Traffic and Highway Engineering
5th Edition
ISBN: 9781305156241
Author: Garber, Nicholas J.
Publisher: Cengage Learning
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Chapter 5, Problem 9P
To determine
The total crash rate and the fatal crash rate for both locations
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Studies were conducted at two sits on rural roads with similar characteristics. The first site was 7.5 miles in length with an Annual Average Daily Traffic (AADT) of 7,400. Over the year-long study period, 42 crashes occurred on this portion of roadway, 5 of them resulting in fatalities. The second site was a 14-mile section with an AADT of 4,700. There were 67 crashes in this section with 5 fatalities. Determine the appropriate crash rates for both locations, and discuss the implications.
Determine the predicted average crash frequency, in crashes (per year), on a 7-mile segment of a rural divided multilane highway with 10-ft lanes and 8-ft paved shoulders that carries an AADT of 15,000 vehicles per day. The proportion of total crashes constituted by CMF-related crashes is 0.55.
A state transportation agency want to evaluate engineering countermeasures applied to a two-lane,two-way rural highway segment.This 4 miles segment has been identified as having 14,19,and 23 total crashes in the last three years,before the implementation of the countermeasures.The AADT at the segment for last three years is 5630 vehicles per day and the AADT for after implementation is 6240 vehicles per day.Compute the expected average crash frequency for the after period, assuming the treatment was not implemented.The segment has the same conditions as the base conditions established for SPF.
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- A 15 mile section of Kapayapaan Road had the following reported accidents for 6 years from 1992. It is required to compute the accident rates of all accidentsarrow_forwardDetermine the crash modification factor that can be used to estimate the change in frequency of the crash type targeted by a proposed improvement that will widen a two-lane rural highway from 9-ft-wide (per lane) to 11-ft-wide (per lane) if the highway has an AADT of 1500 veh/day.arrow_forwardThe crash rate on a heavily traveled two-lane rural highway is abnormally high. Thecorridor is 14 miles long with an ADT of 34,000. An investigation has determined thathead-on collisions are most common with an RMVMT of 4.5 and are caused by vehicles attempting to pass. Determine an appropriate countermeasure and calculate theestimated yearly reduction in total crashes.arrow_forward
- The number of crashes involving trucks (“truck crashes”) has continuously increased as thenumber of truck increases. To analyze the association of truck crash rates with the number oflanes, truck crash rates were compared between two-lane and multi-lane highways as shown inthe table below. Is the standard deviation of truck crash rates significantly higher for two-lanehighways than multi-lane highways?Note: Final answer should be either “The standard deviation of truck crash rates is significantlyhigher for two-lane than multi-lane highways” or “The standard deviation of truck crash rates isnot significantly higher for two-lane than multi-lane highways”.Truck crash rates (crashes/million vehicle-km)Site No. Two-lane highways Multi-lane highways12345670.2560.3420.8421.0210.3610.2620.8610.1880.3120.4210.2850.2250.183arrow_forwardA black spot funding program prioritised a project for widening a two-lane rural highway from 5.4 (=2x2.7) m to 6.6 (=2x3.3) m. This project aimed to reduce a particular set of CMF-related crash types such as single-vehicle-run-off-the-road and multiple-vehicles-head-on, opposite direction sideswipe, and the same direction sideswipes. Therefore the CMFs for lane width on the roadway segment given in Table 5.14 (Text 5.1) apply. Compute the expected average total crash frequency after the widening for the following conditions. The expected average crashes before widening = 25 total crashes/year. AADT on the highway segment, before widening = 1150 veh/day AADT on the highway segment, after widening = 1750 veh/day Proportion of total constituted by CMF-related crashes is 0.574. Answers: Expected average crash frequency after widening = total crashes/year Report your answers to the closest two decimal places without units (i.e., if your answer is 10.258, you should enter 10.26 or if your…arrow_forwardAn engineer wishing to obtain the speed characteristics on a bypass around her city at a confidence level of 95%, and an acceptable limit of 1.0 mi/h collected a total of 130 spot speed samples and determined that the variance is 25 (mi/h)2 . Has the engineer met with all of the requirements of the study?arrow_forward
- Using a surveillance camera, 15 vehicles were observed within 350 m section of the innermost lane of the North Luzon Expressway. Estimate the average spacing of these vehicles.arrow_forwardA two-lane rural roadway segment is expected to have 15 crashes (total) durch year with AADT of 1800 veh/day. The current width of the lane is 10 ft. It is prop width of the lane be increased to 12 ft. What should be expected number of crashes (total) the new condition?arrow_forwardFor a specific rural road segment in northeast Colorado, the total number of crashes as well as the number of fatal crashes have been recorded. Using the data provided with a traffic analysis within two standard deviations (or 95% confidence interval), determine if this site should be flagged for further study. Data: Length of road segment = 2 mi. AADT = 11,350 veh/day Total number of injury crashes for past 5 years = 55 Total number of fatal crashes for past 5 years = 5 Total number of property-only crashes for past 5 years = 100 Average number of statewide injury crashes for rural roads over past 5 years = 1.30 per 106 VMT Average number of statewide fatal crashes for rural roads over past 5 years = 0.02 per 106 VMT Average number of statewide property only crashes for rural roads over past 5 years = .033 per 106 VMT Weighted average crash rate of injury crashes for rural Colorado roads = 3 Weighted average crash rate of fatal crashes for rural Colorado roads = 8 Weighted…arrow_forward
- A 1.5-mile section of a two-lane road has an AADT of 10,000. In a three-year period, there have been 6 fatal accidents and 12 non-fatal accidents. The state allows 350 accidents per 100 mvm for three years, of which 100 are fatal. For which value of confidence level, this highway is considered safe? If the following countermeasures are implemented: widening the existing lane by 2 feet, and widening the existing shoulder by 2 feet paved, and widening the clear zone by 5 feet, what will be the number of accidents reduced if the AADT became 12,000?arrow_forwardA 11.5-mile section of HYW77 has an ADT of 6300. There were 32 crashes in this section with four crashes resulting in fatalities. Determine the total crash rate (all types of crashes) and the fatal crash rates.arrow_forwardThe accident rates for 100 million vehicles miles of travel caused by people attempting to pass a heavily traffic 2 lane rural highway is 6.0. The length of the road is 10 miles with an average daily traffic of 36000. Determine the estimated yearly reduction in total crashes if the crash reduction factor is 0.25.arrow_forward
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