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Pages 28-45

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From page 28...
... 28 S e c t i o n 4 The Transportation Research Information Database (TRID)
From page 29...
... Literature Review 29 • The HCM methods, MOEs selected, LOS thresholds, and so forth are based on expert opinion and not validated with freight drivers except for the Urban Streets Method (Chapter 17)
From page 30...
... 30 incorporating truck Analysis into the Highway capacity Manual a performance perspective, none of these covers weight-to-horsepower ratios, which are a key measure of performance. The impacts of trucks on other modes are modeled differently in the HCM according to the facility type: • On freeways, multilane highways, and two-lane highways, the grade affects the PCEs for trucks.
From page 31...
... Literature Review 31 Control delay at signalized intersections in the current HCM methodology does not consider the probability distribution of heavy vehicles within the queue; it only takes into account saturation flow rate using PCE factors. No provision is available to adjust start up loss or end gain with heavy vehicles in different queue positions.
From page 32...
... 32 incorporating truck Analysis into the Highway capacity Manual as high as 300 lb/hp. It is also important to consider that effective horsepower can vary considerably with various weather, pavement, and vehicle conditions.
From page 33...
... Literature Review 33 HCM 2010 Does Not Deal with Travel Time Reliability A factor of great concern to movers of commercial goods is travel time reliability, which is especially important today because many businesses adhere to what is known as "just-in-time delivery," so they do not have to have large warehousing facilities. This delivery method requires coordination and the ability to accurately determine shipping time.
From page 34...
... 34 incorporating truck Analysis into the Highway capacity Manual In economic analyses used to prioritize projects for investments, separate values of time (VOT) have been assigned to truck movements within the traffic stream.
From page 35...
... Literature Review 35 For freeway conditions, drivers were worried about factors such as road marking in construction zones, narrower lanes, snow being cleared promptly, and evenness of pavements. Drivers tend to prefer the middle lanes, which offer the "smoothest ride." For traffic conditions, a key issue mentioned repeatedly was steady traffic flow.
From page 36...
... 36 incorporating truck Analysis into the Highway capacity Manual average speeds than cars because they cannot perform as many discretionary lane changes to maintain their desired speed. This research did not perform measurements of this presumed preference of drivers to change lanes to maintain desired speed nor did this research attempt to measure or capture the perceptions of motor vehicle carriers or shippers.
From page 37...
... Literature Review 37 They found that drivers and carriers tended to place greater emphasis on different aspects of the highway experience. Drivers placed greatest importance on the quality of the ride and ease of driving (pavement smoothness, fewer maneuvers required, and ease of maneuvers)
From page 38...
... 38 incorporating truck Analysis into the Highway capacity Manual weight above 3.5 metric tons are considered as heavy vehicles (the maximum allowable weight is 40 metric tons, width is 2.6 m, and length is 18.75 m with some exceptions)
From page 39...
... Literature Review 39 Brilon and Bressler (2004) analyzed traffic flow characteristics on freeway upgrades in Germany.
From page 40...
... 40 incorporating truck Analysis into the Highway capacity Manual Saturation Flow Adjustment Factors The Canadian Capacity Guide suggests a number of adjustment factors to adjust the basic saturation flow values for heavy vehicles including other adjustment factors in the absence of directly measured saturation flows at the analyzed intersection. The adjusted saturation flow depends on the basic saturation flow and is a function of the applicable adjustment factors: Equation 5adj basic adjS S f F )
From page 41...
... Literature Review 41 In the same study corridor, Abdelgawad et al.
From page 42...
... 42 incorporating truck Analysis into the Highway capacity Manual 4.2.5 Indonesia The Indonesian highway agency realized that the existing capacity manuals from developed countries could not be successfully implemented in Indonesia because Indonesian traffic characteristics differ from those of developed countries (Indonesian Directorate General of Highways, 1993)
From page 43...
... Literature Review 43 4.2.6 Australia Austroads published Guide to Traffic Management for traffic studies and analysis. The guide provides guidance on traffic analysis for uninterrupted and interrupted flow for various types of intersections.
From page 44...
... 44 incorporating truck Analysis into the Highway capacity Manual and speed of the traffic. Most of the research has provided significant insight about mixed traffic operation in India, but has recommended only static PCE values for trucks and other vehicle categories for different roadways and control conditions.
From page 45...
... Literature Review 45 of trucks -- China, Indonesia, Singapore, Thailand, and Canada subdivide trucks into three or four subtypes.

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