1 package org.opentrafficsim.road.gtu.generator;
2
3 import org.djunits.value.vdouble.scalar.Length;
4 import org.djunits.value.vdouble.scalar.Speed;
5
6 /**
7 * Extends car-following placement with a first-order bounded acceleration (BA) principle. This principle comes down to
8 * reduction of efficiency by increasing headways, as the generated GTU speed is lower than the desired speed. The increased
9 * headways allow for acceleration to occur, allowing faster flow recovery over time.
10 * <p>
11 * Copyright (c) 2013-2024 Delft University of Technology, PO Box 5, 2600 AA, Delft, the Netherlands. All rights reserved. <br>
12 * BSD-style license. See <a href="https://opentrafficsim.org/docs/license.html">OpenTrafficSim License</a>.
13 * </p>
14 * @author <a href="https://github.com/averbraeck">Alexander Verbraeck</a>
15 * @author <a href="https://tudelft.nl/staff/p.knoppers-1">Peter Knoppers</a>
16 * @author <a href="https://github.com/wjschakel">Wouter Schakel</a>
17 */
18 public class CfBaRoomChecker extends CfRoomChecker
19 {
20
21 /** {@inheritDoc} */
22 @Override
23 protected double headwayFactor(final Speed desiredSpeed, final Length desiredHeadway, final Speed generationSpeed,
24 final Length generationHeadway, final Length leaderLength)
25 {
26 if (desiredSpeed.eq(generationSpeed))
27 {
28 return 1.0;
29 }
30 // following state at desired speed (capacity)
31 double k0 = 1.0 / (desiredHeadway.si + leaderLength.si);
32 double q0 = k0 * desiredSpeed.si;
33 // actual state
34 double k = 1.0 / (generationHeadway.si + leaderLength.si);
35 double q = k * generationSpeed.si;
36 // recovery flow qr
37 double qr = q; // if already on free flow branch
38 if (k > k0) // on congestion branch
39 {
40 // recovery wave speed assuming theta = 1 / q0 (theoretically sound and tested to be robust)
41 double rho = generationSpeed.si - q0 / k;
42 // recovery free flow state
43 double kr = (q - rho * k) / (desiredSpeed.si - rho);
44 qr = kr * desiredSpeed.si;
45 }
46 // efficiency factor, > 1 is larger headway, so less efficient
47 return q0 / qr;
48 }
49
50 }