HSM Equations: Urban/Suburban Arterials
ARTERIAL SEGMENTS:
1. The crash prediction models for roadway segments are presented in Equations 12-2 and 12-3:
a. Equation 12-2:
b. Equation 12-3:
2. Equation 12-2 shows that roadway segment crash frequency is estimated as the sum of three components: Nbr, Npedr, and Nbiker. The following equation shows that the SPF portion of Nbr, designated as Nspf rs, is further separated into three components as shown below.
Equation 12-4:
3. Equation 12-10: The SPF for multiple-vehicle nondriveway collisions for base conditions using a and b coefficients from Table 12-3
4. Equation 12-13: The SPF for single-vehicle crashes for base conditions on roadway segments using a and b coefficients from Table 12-5
3. Equation 12-16: Estimates the predicted number of multiple-vehicle driveway-related collisions within a roadway segment using the coefficients in Table 12-7
Crash Modification Factors for Urban/Suburban Arterial Segments:
4. Equation 12-32: CMF for on-street parking, where present, using coefficients in Table 12- 19
5. Equation 12-33: CMF for roadside fixed objects using factors in Tables 12-20 & 12-21
6. CMF for median widths on divided roadway segments of urban and suburban arterials is presented in Table 12-22
7. Equation 12–34: CMF for lighted roadway segments using values in Table 12-23 (recommend replacing noted default values with local data if available)
8. CMF5r—Automated Speed Enforcement , the value of the CMF for automated speed enforcement is 0.95.
PEDESTRIAN AND BICYLIST COLLIONS ON ROADWAY SEGMENTS
1. Equation 12-19: The number of vehicle-pedestrian collisions per year for a roadway segment using coefficients from Table 12-8
2. Equation 12-19: The number of vehicle-bicyclist collisions per year for a roadway segment using coefficients from Table 12-9
URBAN/SUBURBAN ARTERIAL INTERSECTIONS:
1. The crash prediction models for urban or suburban arterial intersections are given by Equations 12-5 and 12-6.
a. Equation 12-5:
b. Equation 12- 6:
2. Equation 12-5 shows that the intersection crash frequency is estimated as the sum of three components: Nbi, Npedi, and Nbikei. Equation 12-7 shows that the SPF portion of Nbi, designated as Nspf int, is further separated into two components by collision type:
a. Equation 12-7:
3. Equation 12-21: The SPF for multiple-vehicle intersection related crashes for base conditions using the appropriate a, b, and c coefficients in Tables 12-10
4. Equation 12-24: The SPF for single-vehicle intersection related crashes for base conditions using the appropriate a, b, and c coefficients in Tables 12-12
Crash Modification Factors for Urban/Suburban Intersections:
1. CMFs for presence of Left-Turn Lanes:
2. CMFs for Type of Left-Turn Phasing
3. CMFs for presence of Right-Turn Lanes
4. Equation 12-35: CMF for Right-Turn-on-Red: The CMF for prohibiting right-turn-on-red on one or more approaches to a signalized intersection. The base condition for CMF4i is permitting a right-turn-on-red at all approaches to a signalized intersection. nprohib = number of signalized intersection approaches for which right-turn-on-red is prohibited.
5. Equation 12-36: CMF for Intersection Lighting (recommend replacing default values with local values if available)
6. Equations 12- 37, 12-38, and 12-39: CMF for installation of Red Light Running Cameras. The values of Nbimv(FI) is available from Equation 12-22, the value of Nbimv(PDO) is available from Equation 12-23, and the value of Nbisv is available from Equation 12-24. The values of pramv(FI), pramv(PDO), premv(FI), and premv(PDO) can be determined from data for the applicable intersection type in Table 12-11.
Pedestrian Collisions at Signalized Intersections:
1. Equation 12-28: Estimates the number of vehicle-pedestrian collisions per year at a signalized intersection
2. Equation 12-29: The SPF for vehicle-pedestrian collisions at signalized intersections using coefficients from Table 12-14
CMFs Vehicle-Pedestrian collisions at Signalized intersections:
1. CMFs for the number of bus stops within 1,000 ft of the center of the intersection are presented in Table 12-28
2. CMF for schools within 1,000 ft of the center of the intersection is presented in Table 12-29.
3. The CMF for the number of alcohol sales establishments within 1,000 ft of the center of an intersection is presented in Table 12-30. Any alcohol sales establishment wholly or partly within 1,000 ft of the intersection may be counted.
Pedestrian Collisions at Stop-Controlled Intersections:
1. Equation 12-30: Estimates the number of vehicle-pedestrian collisions per year for a stop-controlled intersection using factors from Table 12-16
Bicyclist Collisions at Stop-Controlled and Signalized Intersections:
1. Equation 12-30: Estimates the number of vehicle-bicyclist collisions per year for urban/suburban arterial intersections using factors in Table 12-17
For Total Crashes for Arterial Segments and Intersections:
1. Equation 12-8 for total estimated number of crashes within the network or facility limits during a study period of n years: