高速公路用路人對不同獎勵機制之偏好與反應

Abstract

為解決高速公路於平日時段及連續假日尖峰時段之擁塞問題，最常透過以價制量的策略來加以處理。惟當用路人價格彈性低或差別費率有其法規之上限限制時（我國為通行費費率的兩倍），常常難以達成預期交通管理的目標，同時又造成「窮人無法使用高速公路」之爭議。因此，近年來部份國家或城市乃改採獎勵方式來鼓勵尖峰時段旅次之移轉。各國及城市的獎勵制度實施經驗顯示，確實能有效移轉尖峰需求，並大幅減少可能衍生的爭議。 基此，為了解我國用路人對於獎勵制度（高獎額低中獎率或低獎額高中獎率高）之偏好，以及在不同獎勵制度下的反應行為，以供未來我國實施類似策略之參考。因此，本研究參考展望理論(Prospect theory)進行獎勵制度之設計，並利用敘述性偏好實驗(stated preference experiment)進行用路人問卷調查，以了解用路人對於不同獎勵制度的偏好，以及其願意提早出發之時間長短以換取獎勵。其中，本研究利用多項及巢式羅吉特模式建構獎勵制度偏好之模式，再將不同獎勵制度之模式推估效用值代入以Tobit迴歸模式建構的提早出發之願付時間模式，以了解用路人對於不同獎勵制度之偏好以及其可能的反應行為（願付時間之長短）。 由獎勵選擇偏好之多項羅吉特模式推估結果顯示，高速公路用路人最多比例偏好最低獎額高最中獎率（獎金45元，中獎率100%）之獎勵，顯示多數用路人屬於風險趨避者。其次，為最高獎額及最低中獎率（獎金100萬元，中獎率150萬元，中獎率0.003%）的獎勵制度。其中，高教育程度及高所得之用路人較偏好低獎額但高中獎機率之獎勵，但男性及年輕之用路人則反而偏好高獎額但低中獎機率之獎勵。至於Tobit迴歸之推估結果顯示，有66.8%用路人願意在平日通勤旅次提早平均21.7分鐘，其中，又以彈性工時、女性駕駛人願意提早的時間較長（約8.1~16.4分鐘）。連續假日旅次將有75.8%的駕駛人願意提前出發，平均願意提早78.4分鐘。其中，又以女性、40歲以下的駕駛人願意提早的時間更長。由研究結果知，利用獎勵機制確可有效改變用路人出發時間之改變，以達到移峰填谷之交通管理效果。

In order to relieve the traffic congestion during peak hours of weekdays and consecutive holidays, discrimination pricing is undoubtedly the most commonly adopted strategy. However, if the price elasticity of freeway users is low and the upper-bound of discrimination pricing is regulated (for example, double toll rate is the upper-bound of Taiwan), it is hard to attain expected traffic management goal under the pricing strategy. Moreover, arguments against price discrimination to the economically disadvantaged users are easily raised. Therefore, recently, some countries or cities adopt rewarding schemes to encourage shift of peak-hour traffic. Their experiences show the effectiveness of traffic shift with few arguments. Based on this, to investigate the preference of freeway users in Taiwan for the rewarding schemes (such as, high reward but low wining rate or low reward but high wining rate) as well as their responses to various rewarding schemes, this study designs rewarding schemes based on Prospect theory and conducts a questionnaire survey based on stated preference experiment. Multinomial and nested Logit models are used to estimate the rewarding scheme preference model and the estimated utility value of the Logit model is then incorporated into the willingness to pay (in terms of early departure time) model. The estimated Logit model shows that the largest proportion of freeway users prefer to choose the reward with the lowest reward (NT$45) with the highest wining rate (100%), those who are of risk aversion, followed by the highest reward (NT$1.5 millions) with the lowest wining rate (0.003%), those who are risk seeking. Where highly educated, high income users prefer the risk-free reward, while young, male users prefer high-risk reward. Additionally, the estimated Tobit model show that 66.8% commuting drivers are willing to early depart by 21.7 minutes under rewarding schemes, where female, flexible hours drivers are willing to pay 8.1~16.4 minutes more. Meanwhile, 75.8% of drivers in consecutive holidays are willing to early depart by 78.4 minutes under rewarding schemes, where female and aged below 40 drivers are willing to depart even earlier, suggesting that the rewarding schemes can effectively encourage drivers to depart earlier so as to relieve traffic peak.