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Lecture #12

Lecture #12. Arterial Design and LOS Analysis. Objectives. Understand the factors in arterial design Understand how arterial LOS is determined. Kramer’s Ten Ideal Arterial Characteristics. Arterial split of 2/3 to ¾ at all intersections Progressive movement in both directions

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Lecture #12

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  1. Lecture #12 Arterial Design and LOS Analysis

  2. Objectives • Understand the factors in arterial design • Understand how arterial LOS is determined

  3. Kramer’s Ten Ideal Arterial Characteristics • Arterial split of 2/3 to ¾ at all intersections • Progressive movement in both directions • Protected left turns used to protect through traffic • Left turn bays provided, with protected phase • Accommodates large trucks • Protected pedestrian phases and frequent crossings • Transit operations that does not impede through traffic • Transit stops at locations close to protected pedestrian crossings • Accommodate future growth with minimal effect on through traffic • Variable timing and progression to accommodate variable traffic, special events, and emergency vehicles

  4. Arterial Performance • Average travel speed of through vehicles • length = arterial or segment length (miles) • running time per mile = total of running time per mile on all segments in the arterial or section (sec) • total intersection approach delay = totaled over all intersections within the arterial or section (sec)

  5. Signal Spacing • How can the arterial function be preserved? • Why is signal spacing is crucial? • How might signal coordination be better than physical improvements? • What tends to happen to arterial LOS as signalized intersections increase?

  6. Advanced Planning • What needs to be considered when planning an arterial? • What are the general planning alternatives?

  7. Reallocation of Arterial Space Parking • How can arterial space be reallocated?

  8. Other Aspects of Operation • What is the overall effect of intersection modifications? • Turn bays (left and right) • Existence • Length • RTOR • Turn prohibitions • Arrival patterns • Signalization

  9. Other Aspects of Operation (cont.) • What is the overall effect of arterial modifications? • Signal spacing • Parking • Transit • Delivery activity • Land access function • Special use lanes

  10. HCM Procedure for Arterials • What are the steps to the HCM procedure? • Establish arterial to be considered • Determine arterial class and free flow speed • Define arterial sections • Compute running time • Compute intersection approach delay • Compute average travel speed • Section • Facility • Assess the LOS

  11. HCM Procedure for Arterials (cont.) • What does the procedure do? • Why are there different arterial classes? • How are the arterial classes identified?

  12. Arterial Speeds • Free flow speed • How can running speed be determined? • How can intersection delay be determined? • Average travel speed • What is the correct delay to use in arterial evaluation? • D = 1.3d • Where • D = approach delay (sec/veh) • d = stopped delay for the through movement (sec/veh)

  13. Arterial vs Intersection Performance • How are arterial and intersection performance related? • Good arterial performance requires great intersection performance • How can good arterial performance be assured?

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