Ⅰ. Introduction

NEV stands for neighborhood electric vehicle, which would have driving range of 40km in normal driving condition and is equipped with six-12v deep-cycle lead acid batteries[1]. The government will allow the driving on the street from April, 2010. In this trend, a lot of people have interest with NEV, but it is a controversial issue whether it can drive on the street safely, it has no interruption to any other vehicles and it is appropriate to current signal systems or not. In this paper, we want to analyze about these. With simulation program, we can figure out the traffic delay in the intersection and total travel time with two conditions such as NEV and cars mixed all lanes and NEV have to drive only first lane which is the closest to sidewalk.

For this research, we did an experiment with NEV in Ilsan, Gyeonggi and simulation by using VISSIM program. We make some conditions and assumptions for this study, which is related to lane uses and attribute about the cars and NEVs.

This study wants to simulate the day when NEVs will drive with cars on the road and make sure which methodology is appropriate to NEV operation. The government mentioned that NEV should not drive in the road which has over 60km/h speed and have other regulations.

Ⅱ. Background

Regulations for operating an NEV vary by state in the US. The federal government allows state and local governments to make additional safety requirements. For example, the State of New York requires additional safety equipments to include windshield wipers, window defroster, speedometer, odometer and a back-up light. In general, they must be titled and registered, and the driver must be licensed. Because airbags are not required the NEV cannot normally run on highways or freeways. NEVs in many states are restricted to roads with a speed limit of 35 mph which is 56 km/h or less. It is the similar meaning of Zone 30[2].

In United States, the National Highway Traffic Safety Administration has published safety guidelines in the United States which apply to vehicles operating in the 20~25mph speed range. As of January 2007, twenty-five of the fifty states of the United States had passed legislation legalizing the use of low-speed vehicles on highways in the state. By 2009, nearly all 50 states allow NEVs, to drive on their roads. As of end of 2008, 9 states had made it legal to drive them 35 mph speed, most on 45 mph streets. In 2009, Texas has passed a new law (SB129) allowing them to drive 35 mph on 45 mph roads. California and New Mexico have proposed laws in their respective legislatures.

Low-Speed Vehicle (LSV) is another type of electric vehicles. It refer to a legal class of four-wheel vehicles which have a speed range approximately 32km/h to 40km/h that allow them to travel on public roads not accessible to all golf carts or NEV. In Canada, LSV is defined as a vehicle under Motor Vehicle Safety Regulations. It is powered by an electric motor, produces no emissions. E-Jeepney in Philippines also can be an example. LSV is also called Quadricycle in some countries in Europe.

Ⅲ. Approach

We simulated several conditions which are related to operation of NEV by using VISSIM program. VISSIM program is a microscopic simulation program for multi-modal traffic flow modeling and it developed by PTV AG in Germany[3].

In this study, we simulated three scenarios in congested and non-congested conditions, one is that NEVs and cars are mixed in all lanes, the second one is NEVs have to be operated in only first lane and last one is making a queue jump lane and giving priority signal for NEV. Queue jump is a type of roadway geometry typically found in BRT (Bus Rapid Transit) systems. It consists of an additional travel lane on the approach to a signalized intersection. This lane is often restricted to transit vehicles only, though some variations may permit bicyclists, mopeds, and/or motorcycles.

The intent of the lane is to allow the highercapacity vehicles to cut to the front of the queue, reducing the delay caused by the signal and improving the operational efficiency of the transit system. A queue jump lane is generally accompanied by a signal which provides a phase specifically for vehicles within the queue jump. Such a signal reduces the need for a designated receiving lane, as vehicles in the queue jump lane get a “head-start” over other queued vehicles and can therefore merge into the regular travel lanes immediately beyond the signal.

This study sets up maximum speed for NEVs in simulation program to reflect characteristic which cannot make as fast as common vehicles. And signal time is set up straight direction 40sec and left-turn 20sec, so total cycle is 120 sec.

Ⅳ. Results and Analysis

To analyze the relationships about rate of NEV on the road, we assume that there are three conditions, 5%, 10% and 20% NEV operations rates of total traffic. Table 2 shows average speed and total delay according to each scenario. As increase the rate of NEV, average speed decreases in scenario #1 in both conditions, it means that NEVs make a bad effect to intersection delay including other types of vehicles regardless of V/C. Also total delays become larger and larger as the NEVs increase. Also we need to compare with scenario 2 which has the regulation that all NEVs have to be operated only in first lane.

In scenario 1, travel speeds drop as the rates of NEV increase in congested and non-congested conditions. In scenario 2, travel speeds drop from 5% to 10% of NEVs, but when the rate of NEVs becomes 20%, travel speed is improved. In scenario 3 is not same as others. That shows different patterns in congested and non-congested conditions. When noncongested condition, it indicates that queue jump land and priority signal will be helpful when rate of NEVs is 10%. Also this strategy will not work when the V/C is over 0.9.

Table 3 shows that delay also increases in all scenarios and conditions when the rate of NEVs increases.

In Scenario #3, priority signal and queue jump lane cannot give any good effect for all intersection and vehicles because the signal has to cut green time for other vehicles. Table 2 and 3 show that queue jump lane cannot give a good effect to other lanes and itself. Queue jump lanes do not have a lower delay than other scenarios, either.

This paper analyzes the delay in each direction. When the rate of NEVs is 20% of total traffics in non-congested condition, it shows similar patterns when the NEVs share the road with other vehicles. On the other hand, delay of east bound is higher than that of west bound in scenario 3. Congested condition has similar pattern as non-congested condition.

Ⅴ. Conclusion and Limitation

It is certain that the average speed drop and total delay rise will be occurred when NEVs operate on the road because NEVs' speed is not as high as conventional vehicles and do not have acceleration ability like conventional ones. Government mentioned that NEV will be permitted road driving in law soon. In this trend, we need to analyze which methodology is more appropriate to both NEVs and conventional vehicles. First of all, NEVs do not have to disturb the traffic flow, so it is necessary to study and research carefully. In this research, we can make conclusions like below statements.

There is a limitation in this research that the simulation VISSIM cannot reflect all specification about NEV perfectly because the program does not provide function for future transportation yet.