Does anyone see that white Van? – A Vehicle Counting without Disruption

Does anyone see that white Van? – A Vehicle Counting without Disruption Jie Wu, Paul Sabatino, Jennifer Tsan, and Zhen Jiang

Outline • Problem • Challenges • Solution • Implementation issues • Experimental results • Conclusion

Problem • Count/check a certain type of vehicles in the highly dynamic traffic, without any disruption. • Scenario 1: • The Beltway sniper-attacks in October 2002. • Early tips included reports of a white box truck. • Police were pulling over white vans and trucks, but missed the suspects. • Later evidence shows that had this search been a few minute closer, the shooter would have been caught, saving more lives.

Scenario 2: • Hurricane/disaster evacuation • Determine how many cars in the affected area. • Decide the level or scale of evacuation. • Scenario 3: • Settle down a new car dealer (e.g., BMW) • Determine how many BMW running in neighborhood vs. the total vehicle population. • Decide whether it is worth to do.

Challenges • Unpredictable vehicle trajectory, direction, and speed • No disruption (w/o any force to change the above) • Without global control • Scale & cost • Availability • Distributed counting scheme • Delay & inconsistence • Timing • Too early = double-counting • Too late = miscounting • Synchronization! Double-counting? X ? miscounting?

Solution • Two node network Received! X Start! X counting Initial status Traffic flow Receiving No other source Total # of vehicles in the entire network!

Initial + counted volume • w other source • B in 1 • w/o other source • Initiated + counted volume • A in 2, A&B in 3, • B in 5, C in 5&6 • When to count? • Three node network (B≤C) AC and BC are independent CB and BC are independent Starting from A Reaching B B -> C then C->B/C->A A->C then C->A, C->B, B reaching C Reaching C (from A) A->C then C<->B

Complete solution • Seed crossing • Initiate all segments, counting inbound traffic • Any segment without outbound traffic -> waiting • Any segment with outbound traffic -> first vehicle carries out the “counted” token • Any uninitiated crossing + counted traffic coming along one direction/segment • Initiate all segments • Any segment without outbound traffic -> waiting • Any segment with outbound traffic -> first vehicle carries out the “counted” token • Block that incoming direction to avoid double-counting

Any initiated crossing + counted traffic coming along one direction/segment • Confirm the completeness of counting along that segment • Clean up the “counted” token • Block that incoming direction to avoid double-counting • Counting (all vehicles or one target kind of vehicles) • When that crossing and the corresponding segments are initiated (either waiting for outbound traffic), and before that incoming direction is blocked.

Implementation issues • Network model • Each crossing is a checkpoint and has a roadside unit (RSU) installed to detect the traffic from any direction. • The vehicle has built-in equipment to exchange information with RSU and a limited storage to carry that one-bit “counted” information. • Each RSU has a counter for inbound traffic from any direction. • For safety reason, each vehicle does not have any private information exposed, i.e., no identical information.

Implementation issues • Counting result collection • Results are distributed in the entire network at different checkpoints. • After one segment finishes the counting in both directions, the counter will be broadcasted. • Such a broadcast is pipelined with counting process. • Whenever the first site receives the counting results from all other sites, the total result at the global view can form. • Whenever every site receives all the others, each site will have a consistent view of the counting results. The counting can end now in the closed system. • For the open system, the counting will continue unless there is no new vehicle entering the area. • Since that time, no miscounting!

Implementation issues • Extension to real road system • The vehicle has built-in equipment to exchange information with vehicles with V2V communication. • When the vehicle carrying the “counted” token was passed by another vehicle • If that passing vehicle is uncounted→ switch token & counter ++ (if it is also in transfer) • If that passing vehicle is counted → switch token • When the vehicle carrying the “counted” token passes another → counter ++ (if it is in transfer too)

Experimental Results • Map

Closed system • 10~100% daily traffic volume • 1~10 initiating seeds randomly distributed in the networks • Average speed 15 mph (can be upgraded to 25 mph) • 2.2x1.8 square mile area in NYC

max min Time (8-18 min) for all vehicles being counted (but the # is distributed in the entire network)

max min Time (8-18 min) for the target type of vehicles all being counted (but the # is distributed in the entire network)

Time (9-23 min) for forming the counting information at the global level Time (20-45 min) for forming the global counting information at each site

58.16% speedup for counting 58.14% speedup for achieving a global information After 66.67% enhancement of driving speed 57.51% speedup to end the entire process

Open system, through traffic • 10~100% daily traffic volume • 1~10 initiating seeds • Average speed 15 mph • 2.2x1.8 square mile area in NYC

Time (9-23 min) to achieve a global counting information (at one of the checkpoint distributed in the entire network) Time (20-45 min) to ensure each site have a synchronized, consistent view Miscounting in the above preparation phase

30~40% speedup for counting 30~40% speedup for achieving consistent views After 66.67% enhancement of driving speed

20~30% speedup for counting 20~30% speedup for achieving consistent views After 50% reduction of counting area

Conclusion • The results are consistent vs. the traffic throughput and the number of initiating seeds. • No difference between counting all vehicles and counting a subset of vehicles. • The effect of vehicle speed and counting area size is considerable and acceptable. • The difference between open system and closed system is ignorable. • The speedup caused by introducing more initiating seeds is limited.

Comments and Questions? • Thank you!

Does anyone see that white Van? – A Vehicle Counting without Disruption