TRAFFIC AND SAFETY NOTE 97B SUBJECT: PURPOSE: Incentive/Disincentive Clause To Provide Guidance for Calculating Capacity in Determining if an Incentive/Disincentive is Warranted COORDINATING UNIT: Geometric Design Unit INFORMATION: To justify an incentive/disincentive (I/D) clause, delay-related user costs must exceed the I/D dollar amount. Generally, the I/D dollar value should not exceed five percent of the construction contract. Determining the impact on capacity may also be useful in determining the impact on the Central Business District or as a Context Sensitive Measure. The attached information can be used as an initial tool to estimate capacity in determining whether or not an I/D clause is warranted for a construction project. Please also see Note 91-Series for Guidelines for Maintaining Traffic Capacity. For more information on work zone management see the Work Zone Safety and Mobility Manual. 97B (NEW) 1 of 7 7/8/28
GUIDANCE FOR CALCULATING CAPACITY in DETERMINING if an INCENTIVE/DISINCENTIVE CLAUSE Is WARRANTED The attached tables can be used as an initial tool to estimate capacity in determining whether or not an incentive/disincentive (I/D) clause is warranted for a construction project. To justify the clause, delay-related user costs may exceed the I/D dollar amount. Generally, the I/D dollar value should not exceed five percent of the construction contract. Normally, congestion occurs each time traffic demand exceeds the capacity of the roadway under consideration. Since the Design Hourly Volume (DHV) is readily available, it can be used and compared to the appropriate capacity presented in the attached tables. When DHV exceeds available capacity, an incentive/disincentive analysis can be performed to determine the amount of user delay. Twenty-four hour counts and the maintaining traffic plan are required to perform this analysis. Currently, the department uses the construction congestion (C3) program to estimate total user delay cost associated with construction activities. (Contact the Traffic and Safety Region Services area of Construction & Technology for more information on the C3 program.) The total delay cost calculated by this program is the sum of speed and backup delay. Speed delay is the difference in time to travel the distance through a work zone (or around it if a detour is required) during construction and the time it would take if there were no construction. Backup delay is the length of time a vehicle spends in queue before entering a work zone. Backup delay occurs when traffic demand exceeds work zone capacity. If a designated detour is present, a traffic distribution model should be used to estimate traffic volumes using the detour and traffic volumes still traveling through the work zone. The C3 program can then be used to estimate user costs. CAPACITY DURING TRAFFIC REGULATING OPERATIONS Attached is a chart and graph showing capacity during traffic regulating operations on two-lane roadways. The capacity of a traffic regulating operation is directly related to the length of the traffic regulating zone. For example, if the posted speed during the traffic regulating operation is 35 mph and traffic demand is 1, vph, the length of the traffic regulating operation should not exceed.7 miles (1.12 km). The C3 program can be used to calculate user delay. 97B (NEW) 2 of 7 7/8/28
RECOMMENDED DIRECTIONAL WORK ZONE CAPACITIES FOR FREEWAYS NUMBER OF LANES Normal Open VPH (vehicles per hour) AVERAGE CAPACITY of AVAILABLE LANES VPHPL (vehicles per hour per lane) 3 1 1,4 1,4 2 1 1,55 1,55 5 2 3,2 1,6 4 2 3,4 1,7 3 2 3,4 1,7 4 3 5,25 1,75 ADJUSTMENTS 1. If the percentage of trucks is greater than 1 percent, reduce VPH by 1 percent. 2. If an entrance ramp is within the closure zone, reduce the volume of the freeway lane by the minimum of: a. Ramp entering volume in VPHPL b. 8 VPHPL whichever is smaller. 3. Add (or subtract) 1% of the VPH for above (or below) average work activities. a. Work activities which are in close proximity and/or involve larger equipment and numbers of workers would decrease capacity. c. Work activities which involve minimal noise and dust and are remote from open travel lanes would increase capacity. 97B (NEW) 3 of 7 7/8/28
RECOMMENDED WORK ZONE CAPACITIES SIGNALIZED ROADWAYS Directional Capacity for Divided Roadways or One-way Streets (VPH) Number of Lanes Open 1 2 3 4 525 1,25 1,475 Greentime % 5 68 1,3 1,875 6 825 1,6 2,3 Bi-directional Capacity for Undivided Roadways (VPH) Left Turn Prohibited Number of Lanes Open 2 4 4 1,5 2,5 Greentime % 5 1,36 2,6 6 1,65 3,2 Bi-Directional Capacity for Undivided Roadways (VPH) 1 Percent Lefts Number of Lanes Open 2 3 (Center Left Turn Lanes) 3 (Center Left Turn Lanes) 4 Used Greentime % Split Permissive Protected Split 4 36 15 72 79 5 53 13 19 11 6 7 159 142 142 - Design Hourly Volume (DHV) for divided roadway is directional as shown in the Sufficiency Rating Manual. - Design Hourly Volume (DHV) for undivided roadway is bi-directional as shown in the Sufficiency Rating Manual. - Above capacities are based on 8-second cycle length. - Greentime % is the total greentime available for the roadway under construction. ADJUSTMENT If the percentage of heavy trucks > 1 percent, reduce capacity by 1 percent. 97B (NEW) 4 of 7 7/8/28
CAPACITY IN TRAFFIC REGULATOR ZONES LENGTH OF TRAFFIC 25 MPH POSTED 3 MPH POSTED 35 MPH POSTED 4 MPH POSTED 45 MPH POSTED 5 MPH POSTED 55 MPH POSTED REGULATOR ZONE, MI (KM) CAPACITY (VPH) CAPACITY (VPH) CAPACITY (VPH) CAPACITY (VPH) CAPACITY (VPH) CAPACITY (VPH) CAPACITY (VPH).1 (.16) 815 98 1158 1161 1163 1165 1166.2 (.32) 782 955 1136 1141 1146 1149 1152.3 (.48) 75 93 1112 112 1128 1133 1138.4 (.64) 725 9 188 199 111 1117 1123.5 (.8) 68 87 163 177 191 11 118.6 (.96) 65 85 137 155 172 183 193.7 (1.12) 625 815 11 131 152 165 177.8 (1.28) 59 79 982 17 131 146 161.9 (1.45) 55 75 953 982 11 127 144 1. (1.61) 5 715 922 955 988 18 127 1.1 (1.77) 47 695 89 928 966 988 11 1.2 (1.93) 43 69 857 9 943 968 992 1.3 (2.1) 39 61 822 871 919 947 974 1.4 (2.25) 35 57 786 84 894 925 955 1.5 (2.41) 315 53 748 88 868 92 936 1.6 (2.57) 27 49 78 775 842 879 916 1.7 (2.74) 21 43 666 74 814 855 896 1.8 (2.89) 17 4 622 74 786 831 875 1.9 (3.5) 11 34 575 666 756 85 854 2. (3.22) 8 3 526 626 726 779 832 2.1 (3.38) 2 25 475 585 694 752 89 2.2 (3.54) 2 42 541 661 724 786 2.3 (3.7) 15 363 495 627 695 762 2.4 (3.86) 8 32 447 591 664 737 2.5 (4.2) 1 237 396 554 633 711 D R A F T Michigan Department of Transportation TRAFFIC AND SAFETY NOTE INCENTIVE/DISINCENTIVE CLAUSE DRAWN BY: DFK 2/27/8 CHECKED BY: Note 97B JAT PLAN DATE: 5 OF 7 FILE: PW RD TS T Dev Note97B tsn.dgn REV. 2/27/28 SHEET
.1.2.3.4.5.6.7.8.9 1. 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 2. CAPACITY (VPH) BOTH DIRECTIONS 13 12 11 1 9 8 7 6 5 4 3 2 1 CAPACITY IN TRAFFIC REGULATOR ZONES - ENGLISH 55 MPH POSTED 35 MPH POSTED LENGTH OF TRAFFIC REGULATING ZONE IN MILES 45 MPH POSTED D R A F T Michigan Department of Transportation TRAFFIC AND SAFETY NOTE INCENTIVE/DISINCENTIVE CLAUSE DRAWN BY: DFK 2/27/8 CHECKED BY: JAT PLAN DATE: FILE: PW RD TS T Note97B tsn.dgn Note 97B SHEET 6 OF7 REV. 2/27/28
.2.4.6.8 1. 1.2 1.4 1.6 1.8 2. 2.2 2.4 2.6 2.8 3. 3.2 3.4 3.6 3.8 4. CAPACITY (VPH) BOTH DIRECTIONS 13 12 11 1 9 8 7 6 5 4 3 2 1 CAPACITY IN TRAFFIC REGULATOR ZONES - METRIC 35 MPH POSTED LENGTH OF TRAFFIC REGULATING ZONE IN KILOMETERS 55 MPH POSTED 45 MPH POSTED D R A F T Michigan Department of Transportation TRAFFIC AND SAFETY NOTE INCENTIVE/DISINCENTIVE CLAUSE DRAWN BY: DFK 2/27/8 CHECKED BY: JAT PLAN DATE: FILE: PW RD TS T Dev Note97B tsn.dgn Note 97B SHEET 7 OF 7 REV. 2/27/28