TD-S

This is an experimental implementation of TD-S, a routing algorithm that takes time-dependent arc weights into account. This repository contains only the TD-S code but not the data used in the TD-S paper. Unfortunately, access to this data is restricted by an NDA. Without TD-data this code will not be of much use to you.

The TD-S code makes heavy use of RoutingKit. The TD-S makefiles assume that RoutingKit is installed system-wide. If it is only installed locally, then you will have to adjust the makefile.

Input format

The input data is split across several files. Each file is the binary dump of an array of 32-bit unsigned integers or of 32-bit floating points. The files are:

first_out
head
first_ipp_of_arc
ipp_departure_time
ipp_travel_time
latitude
longitude

All nodes have IDs between 0 and node_count-1. Arcs are always directed. Every directed arc has an ID between 0 and arc_count-1. Further, every interpolation point (IPP) has an ID between 0 and ipp_count-1.

The IDs of arcs with tail/source x are first_out[x], first_out[x]+1 ... first_out[x+1]-1. The head/target node of an arc with ID xy is head[xy]. Every arc is associated with a piece-wise linear function that has at least one interpolation point. We assume that these functions are periodic with a period length of one day. An arc with ID xy has the interpolation points with IDs first_ipp_of_arc[xy], first_ipp_of_arc[xy]+1 ... first_ipp_of_arc[xy+1]-1. The departure time of an interpolation point with id ipp is stored in ipp_departure_time[ipp]. The travel time is stored in ipp_travel_time[ipp]. Both times are represented as milliseconds since the start of the day. The interpolation points must be sorted by departure time. latitude[x] is the latitude as floating point of the node with ID x. longitude[x] is the longitude as floating point of the node with ID x.

Preprocessing

There are two commandline tools to extract time-windows.

compute_freeflow_weight first_ipp_of_arc_file ipp_departure_time_file ipp_travel_time_file output_weight_file
compute_time_window_weight window_begin window_end first_ipp_of_arc_file ipp_departure_time_file ipp_travel_time_file output_weight_file

CHs are build using RoutingKit's compute_contraction_hierarchy tool.

compute_contraction_hierarchy first_out head weight ch

Freeflow Preprocessing

To run the Freeflow preprocessing execute

compute_freeflow_weight input/{first_ipp_of_arc,ipp_departure_time,ipp_travel_time} freeflow
compute_contraction_hierarchy input/{first_out,head} freeflow freeflow_ch

TD-S+4 Preprocessing

To run the TD-S+4 preprocessing execute

mkdir -p win4
mkdir -p ch4
for W in 0_5 6_9 11_14 16_19
do
	B=${W%_*}
	E=${W##*_}
	compute_time_window_weight $[$B*60*60*1000] $[$E*60*60*1000] input/{first_ipp_of_arc,ipp_departure_time,ipp_travel_time} win4/$W
	compute_contraction_hierarchy input/{first_out,head} win4/$W ch4/$W
done

TD-S+9 Preprocessing

To run the TD-S+9 preprocessing execute

mkdir -p win9
mkdir -p ch9
for W in 0_240 350_370 410_430 470_490 600_720 720_840 960_1020 1020_1080 1140_1260
do
	B=${W%_*}
	E=${W##*_}
	compute_time_window_weight $[$B*60*1000] $[$E*60*1000] input/{first_ipp_of_arc,ipp_departure_time,ipp_travel_time} win9/$W
	compute_contraction_hierarchy input/{first_out,head} win9/$W ch9/$W
done

TD-S+D Preprocessing

Either use FlowCutter to compute a CCH contraction order or use the IntertialFlow implementation bundled with RoutingKit. Using RoutingKit you run

compute_nested_dissection_order input/{first_out,head,latitude,longitude} cch_order

You must also run the TD-S+4 or TD-S+9 preprocessing.

Running TD-S

To run TD-S use the run_td_s command. The Freeflow heuristic is a special case of TD+S.

run_td_s promts you for a source stop, a source time, and a target stop on the commandline. If you enter this information, it will dump various statistics of this query onto the standard output.

Running Freeflow

To run Freeflow execute

run_td_s input/{first_out,head,first_ipp_of_arc,ipp_departure_time,ipp_travel_time} freeflow_ch

Running TD-S+4

To run TD-S+4 execute

run_td_s input/{first_out,head,first_ipp_of_arc,ipp_departure_time,ipp_travel_time} ch4/*

Running TD-S+9

To run TD-S+9 execute

run_td_s input/{first_out,head,first_ipp_of_arc,ipp_departure_time,ipp_travel_time} ch9/*

Running TD-S+P

To run TD-S+P use the run_td_s_p command.

run_td_s_p promts you for a source stop and a target stop on the commandline. If you enter this information, it will dump various statistics of this query onto the standard output.